Search This Blog

Saturday, January 13, 2024

Penal labour

From Wikipedia, the free encyclopedia
https://en.wikipedia.org/wiki/Penal_labour
Male convicts sewing at the Văcărești prison in Bucharest, Romania, 1930s.
Female convicts chained together by their necks for work on a road. Dar es Salaam, Tanganyika c.1890–1927.

Penal labour is a term for various kinds of forced labour that prisoners are required to perform, typically manual labour. The work may be light or hard, depending on the context. Forms of sentence involving penal labour have included involuntary servitude, penal servitude, and imprisonment with hard labour. The term may refer to several related scenarios: labour as a form of punishment, the prison system used as a means to secure labour, and labour as providing occupation for convicts. These scenarios can be applied to those imprisoned for political, religious, war, or other reasons as well as to criminal convicts.

Large-scale implementations of penal labour include labour camps, prison farms, penal colonies, penal military units, penal transportation, or aboard prison ships.

Punitive versus productive labour

Punitive labour, also known as convict labour, prison labour, or hard labour, is a form of forced labour used in both the past and the present as an additional form of punishment beyond imprisonment alone. Punitive labour encompasses two types: productive labour, such as industrial work; and intrinsically pointless tasks used as primitive occupational therapy, punishment, or physical torment.

Sometimes authorities turn prison labour into an industry, as on a prison farm or in a prison workshop. In such cases, the pursuit of income from their productive labour may even overtake the preoccupation with punishment or reeducation as such of the prisoners, who are then at risk of being exploited as slave-like cheap labour (profit may be minor after expenses, e.g. on security). This is sometimes not the case, and the income goes to defray the costs of the prison.

Victorian inmates commonly worked the treadmill. In some cases, it was productive labour to grind grain (an example of using convict labour to meet costs); in others, it served no purpose. Similar punishments included turning the crank machine or carrying cannonballs. Semi-punitive labour also included oakum-picking: teasing apart old tarry rope to make caulking material for sailing vessels.

British Empire

Prisoners at the treadmill in Pentonville Prison, London, 1895

Imprisonment with hard labour was first introduced into English law with the Criminal Law Act 1776 (16 Geo. 3. c. 43), also known as the "Hulks Act", which authorised prisoners being put to work on improving the navigation of the River Thames in lieu of transportation to the North American colonies, which had become impossible due to the American War of Independence.

The Penal Servitude Act 1853 (16 & 17 Vict. c. 99) substituted penal servitude for transportation to a distant British colony, except in cases where a person could be sentenced to transportation for life or for a term not less than fourteen years. Section 2 of the Penal Servitude Act 1857 (20 & 21 Vict. c. 3) abolished the sentence of transportation in all cases and provided that in all cases a person who would otherwise have been liable to transportation would be liable to penal servitude instead. Section 1 of the Penal Servitude Act 1891 makes provision for enactments which authorise a sentence of penal servitude but do not specify a maximum duration. It must now be read subject to section 1(1) of the Criminal Justice Act 1948.

Sentences of penal servitude were served in convict prisons and were controlled by the Home Office and the Prison Commissioners. After sentencing, convicts would be classified according to the seriousness of the offence of which they were convicted and their criminal record. First time offenders would be classified in the Star class; persons not suitable for the Star class, but without serious convictions would be classified in the intermediate class. Habitual offenders would be classified in the Recidivist class. Care was taken to ensure that convicts in one class did not mix with convicts in another.

Penal servitude included hard labour as a standard feature. Although it was prescribed for severe crimes (e.g. rape, attempted murder, wounding with intent, by the Offences against the Person Act 1861) it was also widely applied in cases of minor crime, such as petty theft and vagrancy, as well as victimless behaviour deemed harmful to the fabric of society. Notable recipients of hard labour under British law include the prolific writer Oscar Wilde (after his conviction for gross indecency), imprisoned in Reading Gaol.

Labour was sometimes useful. In Inveraray Jail from 1839 prisoners worked up to ten hours a day. Most male prisoners made herring nets or picked oakum (Inveraray was a busy herring port); those with skills were often employed where their skills could be used, such as shoemaking, tailoring or joinery. Female prisoners picked oakum, knitted stockings or sewed.

Forms of labour for punishment included the treadmill, shot drill, and the crank machine.

Treadmills for punishment were used for decades in British prisons beginning in 1818; they often took the form of large paddle wheels some 20 feet in diameter with 24 steps around a six-foot cylinder. Prisoners had to work six or more hours a day, climbing the equivalent of 5,000 to 14,000 vertical feet. While the purpose was mainly punitive, the mills could have been used to grind grain, pump water, or operate a ventilation system.

Shot drill involved stooping without bending the knees, lifting a heavy cannonball slowly to chest height, taking three steps to the right, replacing it on the ground, stepping back three paces, and repeating, moving cannonballs from one pile to another.

The crank machine was a device which turned a crank by hand which in turn forced four large cups or ladles through sand inside a drum, doing nothing useful. Male prisoners had to turn the handle 6,000–14,400 times over the period of six hours a day (1.5–3.6 seconds per turn), as registered on a dial. The warder could make the task harder by tightening an adjusting screw.

Convict labourers in Australia in the early 20th century

The British penal colonies in Australia between 1788 and 1868 provide a major historical example of convict labour, as described above: during that period, Australia received thousands of transported convict labourers, many of whom had received harsh sentences for minor misdemeanours in Britain or Ireland.

As late as 1885, 75% of all prison inmates were involved in some sort of productive endeavour, mostly in private contract and leasing systems. By 1935, the portion of prisoners working had fallen to 44%, and almost 90% of those worked in state-run programmes rather than for private contractors.

England and Wales

Prisoners picking oakum at Coldbath Fields Prison in London, circa 1864

Penal servitude was abolished for England and Wales by section 1(1) of the Criminal Justice Act 1948. Every enactment conferring power on a court to pass a sentence of penal servitude in any case must be construed as conferring power to pass a sentence of imprisonment for a term not exceeding the maximum term of penal servitude for which a sentence could have been passed in that case immediately before the commencement of that Act.

Imprisonment with hard labour was abolished by section 1(2) of that Act.

Northern Ireland

Penal servitude was abolished for Northern Ireland by section 1(1) of the Criminal Justice Act (Northern Ireland) 1953. Every enactment which operated to empower a court to pass a sentence of penal servitude in any case now operates so as to empower that court to pass a sentence of imprisonment for a term not exceeding the maximum term of penal servitude for which a sentence could have been passed in that case immediately before the commencement of that Act.

Imprisonment with hard labour was abolished by section 1(2) of that Act.

Scotland

Penal servitude was abolished in Scotland by section 16(1) of the Criminal Justice (Scotland) Act 1949 on 12 June 1950, and imprisonment with hard labour was abolished by section 16(2) of the act.

Every enactment conferring power on a court to pass a sentence of penal servitude in any case must be construed as conferring power to pass a sentence of imprisonment for a term not exceeding the maximum term of penal servitude for which a sentence could have been passed in that case immediately before 12 June 1950. But this does not empower any court, other than the High Court, to pass a sentence of imprisonment for a term exceeding three years.

See section 221 of the Criminal Procedure (Scotland) Act 1975 and section 307(4) of the Criminal Procedure (Scotland) Act 1995

China

In pre-Maoist China, a system of labour camps for political prisoners operated by the Kuomintang forces of Chiang Kai-shek existed during the Chinese Civil War from 1938 to 1949. Young activists and students accused of supporting Mao Zedong and his communists were arrested and re-educated in the spirit of anti-communism at the Northwestern Youth Labor Camp.

After the communists took power in 1949 and established the Communist China, laojiao (Re-education through labour) and laogai (Reform through labour) was (and still is in some cases) used as a way to punish political prisoners. They were intended not only for criminals, but also for those deemed to be counter-revolutionary (political and/or religious prisoners). According to an Al Jazeera special report on slavery, China has the largest penal labour system in the world today. Often these prisoners are used to produce products for export to the West. Xinjiang internment camps represent a major source of penal labour in China according to controversial expert, Adrien Zenz. Since 2002, some prisoners have been eligible to receive payment for their labour.

France

Prison inmates can work either for the prison (directly, by performing tasks linked to prison operation, or for the Régie Industrielle des Établissements Pénitentiaires, which produces and sells merchandise) or for a private company, in the framework of a prison/company agreement for leasing inmate labour. Work ceased being compulsory for sentenced inmates in France in 1987. From the French Revolution of 1789, the prison system has been governed by a new penal code. Some prisons became quasi-factories, in the nineteenth century, many discussions focused on the issue of competition between free labour and prison labour. Prison work was temporarily prohibited during the French Revolution of 1848. Prison labour then specialised in the production of goods sold to government departments (and directly to prisons, for example guards' uniforms), or in small low-skilled manual labour (mainly subcontracting to small local industries).

Forced labour was widely used in the African colonies. One of the most emblematic projects, the construction of the Congo-Ocean railway (140 km or 87 miles) cost the lives of 17,000 indigenous workers in 1929. In Cameroon, the 6,000 workers on the Douala-Yaoundé railway line had a mortality rate of 61.7% according to a report by the authorities. Forced labour was officially abolished in the colonies in 1946 under pressure from the Rassemblement démocratique africain and the French Communist Party. In fact, it lasted well into the 1950s.

India

Only convicts sentenced to "rigorous imprisonment" have to undertake work during their prison term. A 2011 Hindustan Times article reported that 99% of convicts that receive such sentences rarely undertake work because most prisons in India do not have sufficient demand for prison labour. In the Indian Penal Code prior to 1949, Many sections prescribed penal servitude for life as a viable punishment. This was removed by Act No. XVII of 1949, Simply known as the Criminal Law (Removal of Racial Discriminations) Act, 1949 

Ireland

Penal servitude was abolished in Ireland by section 11(1) of the Criminal Law Act, 1997.

Every enactment conferring a power on a court to pass a sentence of penal servitude in any case must be treated as an enactment empowering that court to pass a sentence of imprisonment for a term not exceeding the maximum term of penal servitude for which a sentence could have been passed in that case immediately before the commencement of the Criminal Law Act 1997.

In the case of any enactment in force on 5 August 1891 (the date on which section 1 of the Penal Servitude Act 1891 came into force) whereby a court had, immediately before the commencement of the Criminal Law Act 1997, power to pass a sentence of penal servitude, the maximum term of imprisonment may not exceed five years or any greater term authorised by the enactment.

Imprisonment with hard labour was abolished by section 11(3) of that Act.

Japan

Most Japanese prisoners are required to engage in prison labour, often in manufacturing parts which are then sold cheaply to private Japanese companies. This practice has raised charges of unfair competition since the prisoners' wages are far below market rate.

During the early Meiji era, in Hokkaido many prisoners were forced to engage in road construction (Shūjin dōro (囚人道路)), mining, and railroad construction, which were severe. It was thought to be a form of unfree labour. It was replaced by indentured servitude (Takobeya-rōdō (タコ部屋労働)).

Netherlands

(Hard) penal labour does not exist in the Netherlands, but a light variant consisting of community service (Dutch: taakstraf) is one of the primary punishments which can be imposed on a convicted offender. The maximum punishment is 240 hours, according to article 22c, part 2 of Wetboek van Strafrecht. The labour must be done in their free time. Reclassering Nederland keeps track of those who were sentenced to community services.

New Zealand

The Criminal Justice Act 1954 abolished the distinction between imprisonment with and without hard labour and replaced 'reformative detention' with 'corrective training', which was later abolished on 30 June 2002.

North Korea

North Korean prison camps can be differentiated into internment camps for political prisoners (Kwan-li-so in Korean) and reeducation camps (Kyo-hwa-so in Korean). According to human rights organisations, the prisoners face forced hard labour in all North Korean prison camps. The conditions are harsh and life-threatening and prisoners are subject to torture and inhumane treatment.

Soviet Union

Another historically significant example of forced labour was that of political prisoners and other persecuted people in labour camps, especially in totalitarian regimes since the 20th century where millions of convicts were exploited and often killed by hard labour and bad living conditions. For much of the history of the Soviet Union and other Communist states, political opponents of these governments were often sentenced to forced labour camps. These forced labour camps are called Gulags, an acronym for the government organization that was in charge of them. The Soviet Gulag camps were a continuation of the punitive labour system of Imperial Russia known as katorga, but on a larger scale. The kulaks were some of the first victims of the Soviet Union's forced labour system. Starting in 1930, nearly two million kulaks were taken to camps in unpopulated regions of the Soviet Union and forced to work in very harsh conditions. Most inmates in the Gulag were ordinary criminals: between 1934 and 1953 there were only two years, 1946 and 1947, when the number of counter-revolutionary prisoners exceeded that of ordinary criminals, partly because the Soviet state had amnestied 1 million ordinary criminals as part of the victory celebrations in 1945. At the height of the purges in the 1930s political prisoners made up 12% of the camp population; at the time of Joseph Stalin's death just over one-quarter. In the 1930s, many ordinary criminals were guilty of crimes that would have been punished with a fine or community service in the 1920s. They were victims of harsher laws from the early 1930s, driven, in part, by the need for more prison camp labour

The Gulags constituted a large portion of the Soviet Union's overall economy. Over half of the tin produced in the Soviet Union was produced by the Gulags. In 1951, the Gulags extracted over four times as much gold as the rest of the economy. Gulag camps also produced all of the diamonds and platinum in the Soviet Union, and forced labourers in the Gulags constituted approximately one fifth of all construction labourers in the Soviet Union.

Between 1930 and 1960, the Soviet regime created many labour camps in Siberia and Central Asia. There were at least 476 separate camp complexes, each one comprising hundreds, even thousands of individual camps. It is estimated that there may have been 5–7 million people in these camps at any one time. In later years the camps also held victims of Joseph Stalin's purges as well as World War II prisoners. It is possible that approximately 10% of prisoners died each year. Out of the 91,000 German soldiers captured after the Battle of Stalingrad, only 6,000 survived the Gulag and returned home. Many of these prisoners, however, had died of illness contracted during the siege of Stalingrad and in the forced march into captivity. More than half of all deaths occurred in 1941–1944, mostly as a result of the deteriorating food and medicine supplies caused by wartime shortages.

Probably the worst of the camp complexes were the three built north of the Arctic Circle at Kolyma, Norilsk and Vorkuta. Prisoners in Soviet labour camps were sometimes worked to death with a mix of extreme production quotas, brutality, hunger and the harsh elements. In all, more than 18 million people passed through the Gulag, with further millions being deported and exiled to remote areas of the Soviet Union. The fatality rate was as high as 80% during the first months in many camps. Immediately after the start of the German invasion of the Soviet Union during World War II, the NKVD massacred about 100,000 prisoners who awaited deportation either to NKVD prisons in Moscow or to the Gulag.

Taiwan

Inmates in Taiwan are required to work during their stay in prison but receive a wage for their labour.

United States

Federal Prison Industries (FPI; doing business as UNICOR since 1977) is a wholly owned United States government corporation created in 1934 that uses penal labour from the Federal Bureau of Prisons (BOP) to produce goods and services. FPI is restricted to selling its products and services, which include clothing, furniture, electrical components and vehicle parts, to federal government agencies and has no access to the commercial market. State prison systems also use penal labour and have their own penal labour divisions.

The 13th Amendment of the US Constitution, enacted in 1865, explicitly allows penal labour as it states that "neither slavery nor involuntary servitude, except as a punishment for a crime whereof the party shall have been duly convicted, shall exist within the United States, or any place subject to their jurisdiction". Unconvicted detainees awaiting trial cannot be forced to participate in forced rehabilitative labour programs in prison as it violates the Thirteenth Amendment.

Convicts leased to harvest timber in Florida, circa 1915

The "convict lease" system became popular throughout the South following the American Civil War and into the 20th century. Since the impoverished state governments could not afford penitentiaries, they leased out prisoners to work at private firms. Reformers abolished convict leasing in the 20th-century Progressive Era. At the same time, labour has been required at many prisons.

In 1934, federal prison officials concerned about growing unrest in prisons lobbied to create a work program. Private companies got involved again in 1979, when Congress passed a law establishing the Prison Industry Enhancement Certification Program which allows employment opportunities for prisoners in some circumstances.

Penal labour is sometimes used as a punishment in the US military.

Over the years, the courts have held that inmates may be required to work and are not protected by the constitutional prohibition against involuntary servitude. Correctional standards promulgated by the American Correctional Association provide that sentenced inmates, who are generally housed in maximum, medium, or minimum security prisons, be required to work and be paid for that work. Some states require, as with Arizona, all able-bodied inmates to work.

From 2010 to 2015 and again in 2016 and 2018, some prisoners in the US refused to work, protesting for better pay, better conditions and for the end of forced labour. Strike leaders have been punished with indefinite solitary confinement. Forced prison labour occurs in both public and private prisons. The prison labour industry makes over $1 billion per year selling products that inmates make, while inmates are paid very little or nothing in return. In California, 2,500 incarcerated workers fight wildfires for $1 an hour through the CDCR's Conservation Camp Program, saving the state as much as $100 million a year.

The prison strikes of 2018, sponsored by Jailhouse Lawyers Speak and the Incarcerated Workers Organizing Committee, are considered the largest in the country's history. In particular, inmates objected to being excluded from the 13th Amendment which forces them to work for pennies a day, a condition they assert is tantamount to "modern-day slavery".

Prison industries today are often operating at a loss. Some reformers want to remove legal restrictions and change federal employment laws so that workers could be hired on a negotiated laissez-faire basis to work for wages set by the market and the voluntary choices of prisoners to work and employers to pay wages.

Non-punitive prison labour

Inmates sewing in a Brazilian prison

In a number of penal systems, inmates have the possibility of getting jobs. This may serve several purposes. One goal is to give an inmate a meaningful way to occupy their prison time and a possibility of earning some money. It may also play an important role in resocialisation as inmates may acquire skills that would help them to find a job after release. It may also have an important penological function: reducing the monotony of prison life for the inmate, keeping inmates busy on productive activities, rather than, for example, potentially violent or antisocial activities, and helping to increase inmate fitness, and thus decrease health problems, rather than letting inmates succumb to a sedentary lifestyle.

The classic occupation in 20th-century British prisons was sewing mailbags. This has diversified into areas such as engineering, furniture making, desktop publishing, repairing wheelchairs and producing traffic signs, but such opportunities are not widely available, and many prisoners who work perform routine prison maintenance tasks (such as in the prison kitchen) or obsolete unskilled assembly work (such as in the prison laundry) that is argued to be no preparation for work after release. Classic 20th-century American prisoner work involved making license plates; the task is still being performed by inmates in certain areas.

Many businesses, large and small, already make use of prison workshops to produce high quality goods and services and do so profitably. They are not only investing in prisons but in the future of their companies and the country as a whole. I urge others to follow their lead and seize the opportunity that working prisons offer.

David Cameron, UK Prime Minister

A significant amount of controversy has arisen with regard to the use of prison labour if the prison in question is privatised. Many of these privatised prisons exist in the Southern United States, where roughly 7% of the prison population are within privately owned institutions. Goods produced through this penal labour are regulated through the Ashurst-Sumners Act which criminalises the interstate transport of such goods.

The advent of automated production in the 20th and 21st century has reduced the availability of unskilled physical work for inmates.

ONE3ONE Solutions, formerly the Prison Industries Unit in Britain, has proposed the development of in-house prison call centers.

Placentation

From Wikipedia, the free encyclopedia
 
Placentation
Placentation in the human resulting from cleavage at various gestational ages

Placentation refers to the formation, type and structure, or arrangement of the placenta. The function of placentation is to transfer nutrients, respiratory gases, and water from maternal tissue to a growing embryo, and in some instances to remove waste from the embryo. Placentation is best known in live-bearing mammals (theria), but also occurs in some fish, reptiles, amphibians, a diversity of invertebrates, and flowering plants. In vertebrates, placentas have evolved more than 100 times independently, with the majority of these instances occurring in squamate reptiles.

The placenta can be defined as an organ formed by the sustained apposition or fusion of fetal membranes and parental tissue for physiological exchange. This definition is modified from the original Mossman (1937) definition, which constrained placentation in animals to only those instances where it occurred in the uterus.

In mammals

In live bearing mammals, the placenta forms after the embryo implants into the wall of the uterus. The developing fetus is connected to the placenta via an umbilical cord. Mammalian placentas can be classified based on the number of tissues separating the maternal from the fetal blood. These include:

endotheliochorial placentation
In this type of placentation, the chorionic villi are in contact with the endothelium of maternal blood vessels. (e.g. in most carnivores like cats and dogs)
epitheliochorial placentation
Chorionic villi, growing into the apertures of uterine glands ( epithelium). (e.g. in ruminants, horses, whales, lower primates, dugongs)
hemochorial placentation
In hemochorial placentation maternal blood comes in direct contact with the fetal chorion, which it does not in the other two types. It may avail for more efficient transfer of nutrients etc., but is also more challenging for the systems of gestational immune tolerance to avoid rejection of the fetus. (e.g. in higher order primates, including humans, and also in rabbits, guinea pigs, mice, and rats)

During pregnancy, placentation is the formation and growth of the placenta inside the uterus. It occurs after the implantation of the embryo into the uterine wall and involves the remodeling of blood vessels in order to supply the needed amount of blood. In humans, placentation takes place 7–8 days after fertilization.

In humans, the placenta develops in the following manner. Chorionic villi (from the embryo) on the embryonic pole grow, forming chorion frondosum. Villi on the opposite side (abembryonic pole) degenerate and form the chorion laeve (or chorionic laevae), a smooth surface. The endometrium (from the mother) over the chorion frondosum (this part of the endometrium is called the decidua basalis) forms the decidual plate. The decidual plate is tightly attached to the chorion frondosum and goes on to form the actual placenta. Endometrium on the opposite side to the decidua basalis is the decidua parietalis. This fuses with the chorion laevae, thus filling up the uterine cavity.

In the case of twins, dichorionic placentation refers to the presence of two placentas (in all dizygotic and some monozygotic twins). Monochorionic placentation occurs when monozygotic twins develop with only one placenta and bears a higher risk of complications during pregnancy. Abnormal placentation can lead to an early termination of pregnancy, for example in pre-eclampsia.

In lizards and snakes

As placentation often results during the evolution of live birth, the more than 100 origins of live birth in lizards and snakes (Squamata) have seen close to an equal number of independent origins of placentation. This means that the occurrence of placentation in squamata is more frequent than in all other vertebrates combined, making them ideal for research on the evolution of placentation and viviparity itself. In most squamates two separate placentae form, utilising separate embryonic tissue (the chorioallantoic and yolk-sac placentae). In species with more complex placentation, we see regional specialisation for gas, amino acid, and lipid transport. Placentae form following implantation into uterine tissue (as seen in mammals) and formation is likely facilitated by a plasma membrane transformation.

Most reptiles exhibit strict epitheliochorial placentation (e.g. Pseudemoia entrecasteauxii) however at least two examples of endotheliochorial placentation have been identified (Mabuya sp. and Trachylepis ivensi). Unlike eutherian mammals, epitheliochorial placentation is not maintained by maternal tissue as embryos do not readily invade tissues outside of the uterus.

Research

The placenta is an organ that has evolved multiple times independently, evolved relatively recently in some lineages, and exists in intermediate forms in living species; for these reasons it is an outstanding model to study the evolution of complex organs in animals. Research into the genetic mechanisms that underpin the evolution of the placenta have been conducted in a diversity of animals including reptiles, seahorses, and mammals.

The genetic processes that support the evolution of the placenta can be best understood by separating those that result in the evolution of new structures within the animal and those that result in the evolution of new functions within the placenta.

Evolution of placental structures

In all placental animals, placentas have evolved through the utilisation of existing tissues. In viviparous mammals and reptiles placentas form from the intimate interaction of the uterus and a series of embryonic membranes including the chorioallantoic and yolk sac membranes. In guppies placental tissues form between the ovarian tissue and the egg membrane. In pipefish placentas form following the interaction with the egg and the skin.

Despite the placenta forming from pre-existing tissues, in many instances new structures can evolve within these pre-existing tissues. For example, in male seahorses the underbelly skin has become highly modified to form a pouch in which embryos can develop. In mammals and some reptiles, including the viviparous southern grass skink, the uterus becomes regionally specialised to support placental functions, within each of these regions being a new specialised uterine structure. In the southern grass skink three distinct regions of the placenta form which likely perform different functions; the placentome supports nutrient transfer via membrane bound transport proteins, the paraplacentome supports the exchange of respiratory gasses, and the yolk sac placenta supports lipid transport via apocrine secretion.

Evolution of placental functions

Placental functions include nutrient transport, gas exchange, maternal-fetal communication, and waste removal from the embryo. These functions have evolved by a series of general processes such as re-purposing processes found in the ancestral tissues from which a placenta is derived, recruiting the expression of genes expressed elsewhere in the organism to perform new functions in placental tissues, and the evolution of new molecular processes following the formation of new placenta specific genes.

In mammals, maternal-fetal communication occurs via the production of a range of signalling molecules and their receptors in the chorioallantoic membrane of the embryo and the endometrium of the mother. Examination of these tissues in egg-laying and other independently evolved live bearing vertebrates has shown us that many of these signalling molecules are expressed widely in vertebrate species and were probably expressed in the ancestral amniote vertebrate. This suggests that maternal fetal communication has evolved by utilising the existing signalling molecules and their receptors, from which placental tissues are derived.

In plants

In flowering plants, placentation is the attachment of ovules inside the ovary. The ovules inside a flower's ovary (which later become the seeds inside a fruit) are attached via funiculi, the plant part equivalent to an umbilical cord. The part of the ovary where the funiculus attaches is referred to as the placenta.

In botany, the term placentation most commonly refers to the arrangement of ovules inside an ovary. Placentation types include:

  • Basal: The placenta is found in mono to multi carpellary, syncarpous ovary. Usually a single ovule is attached at the base (bottom). E.g.: Helianthus, Tridex, Tagetus.
  • Parietal: It is found in bicarpellary to multicarpellary syncarpous ovary. Unilocular ovary becomes bilocular due to formation of false septum.E.g.: Cucumber
  • Axile : it is found in bicarpellary to multicarpellary syncarpous ovary. The carpels fuse to form septa forming a central axis and ovules are arranged on the axis. E.g.: Hibiscus, lemon, tomato, lilly.
  • Free central : It is found in bicarpellary to multicarpellary syncarpous ovary. Due to degradation of false septum unilocular condition is formed and ovules are arranged on the central axis. E.g.: Dianthus, Primula (primroses)
  • Marginal : It is found in monocarpellary unilocular ovary, placenta forms a rigid along ventral side and ovules are arranged in two vertical rows. E.g.: Pisum sativum (pea)

Prison abolition movement

From Wikipedia, the free encyclopedia
https://en.wikipedia.org/wiki/Prison_abolition_movement

The prison abolition movement is a network of groups and activists that seek to reduce or eliminate prisons and the prison system, and replace them with systems of rehabilitation and education that do not place a focus on punishment and government institutionalization. The prison abolitionist movement is distinct from conventional prison reform, which is the attempt to improve conditions inside prisons.

Some supporters of decarceration and prison abolition also work to end solitary confinement, the death penalty, and the construction of new prisons through non-reformist reform. Others support books-to-prisoner projects and defend the rights of prisoners to have access to information and library services. Some organizations, such as the Anarchist Black Cross, seek total abolishment of the prison system, without any intention to replace it with other government-controlled systems. Many anarchist organizations believe that the best form of justice arises naturally out of social contracts, restorative justice, or transformative justice.

Definition

Scholar Dorothy Roberts takes the prison abolition movement in the United States to endorse three basic theses:

  1. "[T]oday’s carceral punishment system can be traced back to slavery and the racial capitalist regime it relied on and sustained."
  2. "[T]he expanding criminal punishment system functions to oppress black people and other politically marginalized groups in order to maintain a racial capitalist regime."
  3. "[W]e can imagine and build a more humane and democratic society that no longer relies on caging people to meet human needs and solve social problems."

Thus, Roberts situates the theory of prison abolition within an intellectual tradition including scholars such as Cedric Robinson, who developed the concept of racial capitalism, and characterizes the movement as a response to a long history of oppressive treatment of black people in the United States. In Canada, many abolitionists have called Canada's prisons the "new residential schools", which were designed as a cultural genocide of Indigenous people.

Legal scholar Allegra McLeod notes that prison abolition is not merely a negative project of "opening … prison doors", but rather "may be understood instead as a gradual project of decarceration, in which radically different legal and institutional regulatory forms supplant criminal law enforcement." Prison abolition, in McLeod's view, involves a positive agenda that reimagines how societies might deal with social problems in the absence of prisons, using techniques such as decriminalization and improved welfare provision.

Like Roberts, McLeod sees the contemporary theory of prison abolition as linked to theories regarding the abolition of slavery. McLeod notes that W. E. B. Du Bois—particularly in his Black Reconstruction in America—saw abolitionism not only as a movement to end the legal institution of property in human beings, but also as a means of bringing about a "different future" wherein former slaves could enjoy full participation in society. (Angela Davis explicitly took inspiration from Du Bois's concept of "abolition democracy" in her book Abolition Democracy: Beyond Empire, Prisons, and Torture.) Similarly, on McLeod's view, prison abolition implies broad changes to social institutions: "[a]n abolitionist framework", she writes, "requires positive forms of social integration and collective security that are not organized around criminal law enforcement, confinement, criminal surveillance, punitive policing, or punishment."

The abolition of prisons is not only about the closure of prisons. Abolitionist views is also a way to counter the hegemonic discourse, and gives an alternative ways of thinking. It is a way to reconceptualize basic notions like crime, innocence, punishment etc.

Historical development

Anarchism and prison abolition

Anarchist opposition to incarceration can be found in articles written as early as 1851, and is elucidated by major anarchist thinkers such as Proudhon, Bakunin, Berkman, Goldman, Malatesta, Bonano, and Kropotkin.

Personal experiences in prison because of revolutionary activity prompted many anarchists who were “deeply affected by their experiences” to publish their criticisms. In 1886, the trial of eight anarchists following the Haymarket riots brought state repression to public attention. Lucy Parsons, an anarchist and wife of one of the Haymarket eight, embarked on a speaking tour through 17 different states speaking to a total of almost 200,000 people. A single rally in Havana, Cuba, to support the families of the eight accused anarchists raised nearly $1000. Speaking at his trial, in a widely disseminated speech, one of the co-accused, August Spies, stated:

It is not likely that the honorable Bonfield and Grinnell can conceive of a social order not held intact by the policeman's club and pistol, nor of a free society without prisons, gallows, and State's attorneys. In such a society they probably fail to find a place for themselves. And is this the reason why Anarchism is such a "pernicious and damnable doctrine?"

The Anarchist Red Cross, a prisoner support group and the precursor to the Anarchist Black Cross, was founded roughly in 1906. By that year, groups existed in Kiev, Odessa, Bialystok, and trials of its members, led to its spread across Europe and North America. A 2018 guide to starting an Anarchist Black Cross group states that "we need to destroy all the prisons, and free all the prisoners. Our position is an abolitionist stance against the state and it’s prisons."

In 1917, the Anarchist Red Cross would disband and members joined the revolution in Russia. Following the February revolution, political prisoners were released from Russian jails, in a massive wave of amnesties. The Anarchist Red Cross reorganised in 1919 as the Anarchist Black Cross, with some members joining the anarchist insurgent, Nestor Makhno.

Makhno, a Ukrainian anarchist who was freed in 1917 from a life sentence in prison, organised a revolutionary insurgent army along anarchist principles that would come to control a territory of seven-and-a-half million people. Upon taking control of a town, Makhnovists would destroy “all remnants and symbols of slavery: prisons, police and gendarmerie posts were blown up with dynamite or put to the torch.” Prisoners in battle who were not officers were typically welcomed into the ranks of Makhnovists or freed. The Makhnovist revolutionary insurgent army adopted a declaration in 1919, stating

we are against all rigid judicial and police machinery, against any legislative code prescribed once and for all time, for these involve gross violations of genuine justice and of the real protections of the population. These ought not to be organized but should be instead the living, free and creative act of the community. Which is why all obsolete forms of justice — court administration, revolutionary tribunals, repressive laws, police or militia, Cheka, prisons and all other sterile and useless anachronisms — must disappear of themselves or be abolished from the very first breath of the free life, right from the very first steps of the free and living organization of society and the economy.

The Anarchist Black Cross was reconstituted in the aftermath of the Spanish Civil War and Anarchist Revolution. The pressure from the number of anarchist prisoners in need of aid led to the closing of “most of the chapters in the United States and Europe.” Alternative groups, such as the Alexander Berkman Aid Fund and the Society to Aid Anarchist Prisoners in Russia would take their place. Another resurgence was felt in 1967, and, again, in 1979 owing to the efforts of Lorenzo Kom’boa Ervin, whose writings on prison and anarchism are credited as having spread and been foundational to Black anarchism.

Anarchists agitation against prisons in Canada has included Bulldozer, an anti-prison anarchist project founded in Toronto in 1980. Bulldozer was closed after being raided and charged with sedition. The End the Prison Industrial Complex (Epic) was formed in 2009, and Anarchist Black Cross projects emerged throughout the 2000s. Anarchists and abolitionists within Québec organise yearly noise demonstrations outside of prison facilities on New Year's Eve. A campaign to stop the construction of a migrant prison involved anarchists unloading thousands of crickets into the offices of an architectural firm in 2018.

Campaigns to free anarchist prisoners have served as the basis for calling for freedom for all prisoners. June 11, 2011, international solidarity actions for anarchist prisoners Marie Mason and Eric McDavid triggered the start of an international day and week of solidarity with all anarchist prisoners in 2015. 2022's week of solidarity included actions in Poland, Russia, Ukraine, Uruguay, Greece, the UK, and other countries. The 2022-2023 hunger strike of anarchist prisoner Alfredo Cospito led to police skirmishes with protesters in Rome, a Turin cell tower being lit on fire, and a letter with bullets was sent to a newspaper stating "if Alfredo Cospito dies judges will all be targets, two months without food, burn down the prisons." International actions to free Cospito, included the burning of a Strabag excavator in Germany. The Italian placed their embassies on "alert" in response to mobilizations.

The Rojavan Revolution, which many have considered illustrative of, and rooted in, anarchist theory, involved the mass liquidation of prisons and freeing of political prisoners and nonviolent offenders. Neighbourhood based "peace committees," composed of elected community members with, largely, no formal legal education, were created to resolve conflicts using a model of consensus and restorative justice.

Prison Abolition and the New Left

Angela Davis traces the roots of contemporary prison abolition theory at least to Thomas Mathiesen's 1974 book The Politics of Abolition, which had been published in the wake of the Attica Prison uprising and unrest in European prisons around the same time. She also cites activist Fay Honey Knopp's 1976 work Instead of Prisons: A Handbook for Abolitionists as significant in the movement.

Eduardo Bautista Duran and Jonathan Simon point out that George Jackson's 1970 text Soledad Brother drew global attention to the conditions of prisons in the United States and made prison abolition a tenet of the New Left.

Liz Samuels observes that, following the Attica Prison uprising, activists began to coalesce around a vision of abolition, whereas previously they had endorsed a program of reform.

1973 Walpole Prison uprising

In 1973, two years after the Attica Prison uprising, the inmates of Walpole prison, in Massachusetts, formed a prisoners' union to protect themselves from guards, end behavioral modification programs, advocate for the prisoner's right for education and healthcare, gain more visitation rights, work assignments, and to be able to send money to their families.

The union also created a general truce within the prison and race-related violence sharply declined. During the Kwanzaa celebration, black prisoners were placed under lockdown, angering the whole facility and leading to a general strike. Prisoners refused to work or leave their cells for three months, to which the guards responded by beating prisoners, putting prisoners in solitary confinement, and denying prisoners medical care and food.

The strike ended in the prisoners' favour as the superintendent of the prison resigned. The prisoners were granted more visitation rights and work programs. Angered by this, the prison guards went on strike and abandoned the prison, hoping that this would create chaos and violence throughout the prison. But the prisoners were able to create an anarchist community where recidivism dropped dramatically and murders and rapes fell to zero. Prisoners volunteered to cook meals. Vietnam veterans who had been trained as medics took charge of the pharmacy and distribution of medication. Decisions were made in community assemblies.

Guards retook the prison after two months, leading to many prison administrators and bureaucrats quitting their jobs and embracing the prison abolition movement.

Advocates of prison abolition

Anarchist banner in Melbourne Australia, on 16 June 2017

Angela Davis writes: "Mass incarceration is not a solution to unemployment, nor is it a solution to the vast array of social problems that are hidden away in a rapidly growing network of prisons and jails. However, the great majority of people have been tricked into believing in the efficacy of imprisonment, even though the historical record clearly demonstrates that prisons do not work."

Angela Davis and Ruth Wilson Gilmore co-founded Critical Resistance, which is an organization working to "build an international movement to end the Prison Industrial Complex by challenging the belief that caging and controlling people makes us safe." Other similarly motivated groups such as the Prison Activist Resource Center (PARC), a group "committed to exposing and challenging all forms of institutionalized racism, sexism, able-ism, heterosexism, and classism, specifically within the Prison Industrial Complex," and Black & Pink, an abolitionist organization that focuses around LGBTQ rights, all broadly advocate for prison abolition. Furthermore, the Human Rights Coalition, a 2001 group that aims to abolish prisons, and the California Coalition for Women Prisoners, a grassroots organization dedicated to dismantling the PIC, can all be added to the long list of organizations that desire a different form of justice system.

Since 1983, the International Conference on Penal Abolition (ICOPA) gathers activists, academics, journalists, and "others from across the world who are working towards the abolition of imprisonment, the penal system, carceral controls and the prison industrial complex (PIC)," to discuss three important questions surrounding the reality of prison abolition ICOPA was one of the first penal abolitionist conference movements, similar to Critical Resistance in America, but "with an explicitly international scope and agenda-setting ambition."

Anarchists wish to eliminate all forms of state control, of which imprisonment is seen as one of the more obvious examples. Anarchists also oppose prisons given that statistics show incarceration rates affect mainly poor people and ethnic minorities, and do not generally rehabilitate criminals, in many cases making them worse. As a result, the prison abolition movement often is associated with humanistic socialism, anarchism and anti-authoritarianism.

In October 2015, members at a plenary session of the National Lawyers Guild (NLG) released and adopted a resolution in favor of prison abolition.

In Canada, a number of organizations support prison abolition, which includes the Saskatchewan Manitoba Alberta Abolition Organization (SMAAC) or the Toronto Prisoners’ Rights Project. These organizations collaborate and organize on issues of prison abolition and work towards prison abolition.

Disability, mental illness and prison

Prison abolitionists such as Amanda Pustilnik take issue with the fact that prisons are used as a "default asylum" for many individuals with mental illness:

Why do governmental units choose to spend billions of dollars a year to concentrate people with serious illnesses in a system designed to punish intentional lawbreaking, when doing so matches neither the putative purposes of that system nor most effectively addresses the issues posed by that population?

In the United States, there are more people with mental illness in prisons than in psychiatric hospitals. In Canada, mental health issues are 2 to 3 times more prevalent in prisons than in the general population. This statistic is one of the major pieces of evidence that prison abolitionists claim highlights the depravity of the penal system.

Prison abolitionists contend that prisons violate the Constitutional rights (5th and 6th Amendment rights) of mentally ill prisoners on the grounds that these individuals will not be receiving the same potential for rehabilitation as the non-mentally ill prison population. This injustice is sufficient grounds to argue for the abolishment of prisons. Prisons were not designed to be used to house the mentally ill, and prison practices like solitary confinement are damaging to mental health. Additionally, individuals with mental illnesses have a much higher chance of committing suicide while in prison.

In response to the fear that prisons are needed for the most serious cases of mentally ill, Liat Ben-Mosh describe prison abolitionist's' view on the issue: "Many prison abolitionists advocate for transformative justice and healing practices in which no one will be restrained or segregated, while some, like PREAP, believe that there will always be a small percentage of those whose behavior is so unacceptable or harmful that they will need to be incapacitated, socially exiled, or restrained and that this should be done humanely, temporarily, and not in a carceral or punitive manner." Another point raised is that the current focus in criminal justice reform on nonviolent, nonserious and nonsexual offences shrinks the borders and understandings of innocence and guilt.

Aging in prison

The prison abolition movement and prison abolitionists, like Liat Ben-Moshe have taken issue with the treatment of the aging population in prisons. Prolonged sentencing policies have resulted in an increased aging population in prisons as well as the harsh conditions of imprisonment. A number of reasons can contribute to older adult's risk for illness while in prison. Prisons are not intended to be used as nursing homes, hospice or long-term care facilities for the aging prison population.

In Canada, individuals 50 years of age and older in federal custody account for 25% of the federal prison population. Investigations into the Canadian federal penitentiary have found that there is a general failure of the Correctional Service of Canada to meet safe and humane custody and assisting in the rehabilitation and reintegration of offenders into the community. The conditions of confinement of older individuals jeopardize the protection of their human rights. The conditions of the aging population in Canada has been denounced by persons who are incarcerated.

Proposed reforms and alternatives

2022 Spanish-language graffiti in Vallcarca i els Penitents (Barcelona) advocating for the freeing of prisoners.
2022 Catalan-language graffiti in Vallcarca i els Penitents (Barcelona) deeming prisons as torture.

Proposals for prison reform and alternatives to prisons differ significantly depending on the political beliefs behind them. Often they fall in one of three categories from the "Attrition Model", a model proposed by the Prison Research Education Action Project in 1976: moratorium, decarceration, and excarceration. Proposals and tactics often include:

  • Penal system reforms:
  • Prison condition reforms
  • Crime prevention rather than punishment
  • Abolition of specific programs which increase prison population, such as the prohibition of drugs (e.g., the American War on Drugs) and prohibition of prostitution.
  • Education programs to inform people who have never been in prison about the problems
  • Fighting individual cases of wrongful conviction

The United Nations Office on Drugs and Crime published a series of handbooks on criminal justice. Among them is Alternatives to Imprisonment which identifies how the overuse of imprisonment impacts fundamental human rights, especially those convicted for lesser crimes.

Social justice and advocacy organizations such as Students Against Mass Incarceration (SAMI) at the University of California, San Diego often look to Scandinavian countries Sweden and Norway for guidance in regard to successful prison reform because both countries have an emphasis on rehabilitation rather than punishment. According to Sweden's former Prison and Probation Service Director-General, Nils Öberg, this emphasis is popular among the Swedish because the act of imprisonment is considered punishment enough. This focus on rehabilitation includes an emphasis on promoting normalcy for inmates, a charge lead by experienced criminologists and psychologists. In Norway a focus on preparation for societal re-entry has yielded "one of the lowest recidivism rates in the world at 20%, [while] the US has one of the highest: 76.6% of [American] prisoners are re-arrested within five years". The Scandinavian method of incarceration seems to be successful: the Swedish incarceration rate decreased by 6% between 2011 and 2012.

Abolitionist views

Many prison reform organizations and abolitionists in the United States advocate community accountability practices, such as community-controlled courts, councils, or assemblies as an alternative to the criminal justice system.

Abolitionists like Angela Davis recommend four measures as a way to deal with violent and other serious crimes: (1) make mental health care available to all (2) everyone should have access to affordable treatment for substance use disorders (3) make a stronger effort to rehabilitate those who commit criminal offences and (4) employ reparative or restorative justice measures as an accountability tool to reconcile offenders with their victims and undo or compensate the harm done.

Organizations such as INCITE! and Sista II Sista that support women of color who are survivors of interpersonal violence argue that the criminal justice system does not protect marginalized people who are victims in relationships. Instead, victims, especially those who are poor, minorities, transgender or gender non-conforming can experience additional violence at the hands of the state. Instead of relying on the criminal justice system, these organizations work to implement community accountability practices, which often involve collectively-run processes of intervention initiated by a survivor of violence to try to hold the person who committed violence accountable by working to meet a set of demands. For organizations outside the United States see, e.g. Justice Action, Australia.

Some anarchists and socialists contend that a large part of the problem is the way the judicial system deals with prisoners, people, and capital. According to Marxists, in capitalist economies incentives are in place to expand the prison system and increase the prison population. This is evidenced by the creation of private prisons in America and corporations like CoreCivic, formerly known as Correction Corporation of America (CCA). Its shareholders benefit from the expansion of prisons and tougher laws on crime. More prisoners is seen as beneficial for business. Some anarchists contend that with the destruction of capitalism, and the development of social structures that would allow for the self-management of communities, property crimes would largely vanish. There would be fewer prisoners, they assert, if society treated people more fairly, regardless of gender, color, ethnic background, sexual orientation, education, etc.

The demand for prison abolition is a feature of anarchist criminology, which argues that prisons encourage recidivism and should be replaced by efforts to rehabilitate offenders and reintegrate them into communities.

“Nine perspectives for prison abolitionists”

Instead of prisons: a handbook for abolitionists, republished by Critical Resistance in 2005, outlines what they identify as the nine main perspectives for prison abolitionists:

Perspective 1

The imprisonment of a human being is inherently immoral, and while total abolition of the current prison system is not an easy task, it is possible. The first step towards abolition is admitting that prisons cannot be reformed, as a carceral system is founded on brutality and contempt for those imprisoned. Additionally, the current system works to disproportionally imprison poor and working-class people, so its abolition would ensure progress towards equality. Abolitionists see many similarities between today's carceral system and the slavery establishment of the past, and would in fact say that the current system is simply reformed enslavement which perpetuates the same oppressive and discriminatory patterns. But just as superficial reforms could not alter the brutality of the slave system, reforms cannot change a system rooted in racism.

Perspective 2

The abolitionist message requires changing our language and definitions of punishment “treatment” and “inmates”. In order to break away from the prison system, we must use honest language and take back the power of our vocabulary.

Perspective 3

Imprisonment is not a proper response to deviance. Abolitionists promote reconciliation rather than punishment, a perspective seeking to restore both the criminal and the victim while limiting the disruption of their lives in the process.

Perspective 4

Abolitionists advocate for changes beneficial to the prisoner but do so while remaining a non-member of the system. In a similar fashion, abolitionists respect the personhood of system managers but oppose their role in the perpetuation of an oppressive system.

Perspective 5

The abolitionist message extends farther than the traditional helping relationship; Abolitionists identify themselves as allies of the imprisoned, respecting their perspectives as well as the requirements for abolition.

Perspective 6

The empowerment of prisoners and ex-prisoners is crucial to the abolitionist movement. Programs and resources dedicated to reinstating that which has been stripped from them by the prison system are fundamental in putting power back in their own hands.

Perspective 7

Abolitionists believe that citizens are the true source of institutional power which can lead to the abolition of the prison system. Giving or limiting support from certain policies and practices will enable the progression of the abolitionist movement.

Perspective 8

Abolitionists believe that crime is a consequence of a broken society, and recourses must be used towards social programs instead of the funding of prisons. They advocate for public solutions to public problems, producing effects which will benefit everyone in society.

Perspective 9
An emphasis is placed on the correction of society rather than the correction of an individual. It is only in a corrected or caring community that individual redemption and rehabilitation can be achieved. Thus, abolitionists see that the only adequate alternative to the prison system is building a kind of society which has no need for prisons.

Ovule

From Wikipedia, the free encyclopedia
https://en.wikipedia.org/wiki/Ovule

Location of ovules inside a Helleborus foetidus flower

In seed plants, the ovule is the structure that gives rise to and contains the female reproductive cells. It consists of three parts: the integument, forming its outer layer, the nucellus (or remnant of the megasporangium), and the female gametophyte (formed from a haploid megaspore) in its center. The female gametophyte — specifically termed a megagametophyte— is also called the embryo sac in angiosperms. The megagametophyte produces an egg cell for the purpose of fertilization. The ovule is a small structure present in the ovary. It is attached to the placenta by a stalk called a funicle. The funicle provides nourishment to the ovule.

Location within the plant

In flowering plants, the ovule is located inside the portion of the flower called the gynoecium. The ovary of the gynoecium produces one or more ovules and ultimately becomes the fruit wall. Ovules are attached to the placenta in the ovary through a stalk-like structure known as a funiculus (plural, funiculi). Different patterns of ovule attachment, or placentation, can be found among plant species, these include:

  • Apical placentation: The placenta is at the apex (top) of the ovary. Simple or compound ovary.
  • Axile placentation: The ovary is divided into radial segments, with placentas in separate locules. Ventral sutures of carpels meet at the centre of the ovary. Placentae are along fused margins of carpels. Two or more carpels. (e.g. Hibiscus, Citrus, Solanum)
  • Basal placentation: The placenta is at the base (bottom) of the ovary on a protrusion of the thalamus (receptacle). Simple or compound carpel, unilocular ovary. (e.g. Sonchus, Helianthus, Asteraceae)
  • Free-central placentation: Derived from axile as partitions are absorbed, leaving ovules at the central axis. Compound unilocular ovary. (e.g. Stellaria, Dianthus)
  • Marginal placentation: Simplest type. There is only one elongated placenta on one side of the ovary, as ovules are attached at the fusion line of the carpel's margins . This is conspicuous in legumes. Simple carpel, unilocular ovary. (e.g. Pisum)
  • Parietal placentation: Placentae on inner ovary wall within a non-sectioned ovary, corresponding to fused carpel margins. Two or more carpels, unilocular ovary. (e.g. Brassica)
  • Superficial: Similar to axile, but placentae are on inner surfaces of multilocular ovary (e.g. Nymphaea)

In gymnosperms such as conifers, ovules are borne on the surface of an ovuliferous (ovule-bearing) scale, usually within an ovulate cone (also called megastrobilus). In the early extinct seed ferns, ovules were borne on the surface of leaves. In the most recent of these taxa, a cupule (a modified branch or group of branches) surrounded the ovule (e.g. Caytonia or Glossopteris).

Parts and development

Ovule structure (anatropous) 1: nucellus 2: chalaza 3: funiculus 4: raphe

Ovule orientation may be anatropous, such that when inverted the micropyle faces the placenta (this is the most common ovule orientation in flowering plants), amphitropous, campylotropous, or orthotropous (anatropous are common and micropyle is in downward position and chalazal end in on the upper position hence, in amphitropous the anatropous arrangement is tilted 90 degrees and in orthotropus it is completely inverted) . The ovule appears to be a megasporangium with integuments surrounding it. Ovules are initially composed of diploid maternal tissue, which includes a megasporocyte (a cell that will undergo meiosis to produce megaspores). Megaspores remain inside the ovule and divide by mitosis to produce the haploid female gametophyte or megagametophyte, which also remains inside the ovule. The remnants of the megasporangium tissue (the nucellus) surround the megagametophyte. Megagametophytes produce archegonia (lost in some groups such as flowering plants), which produce egg cells. After fertilization, the ovule contains a diploid zygote and then, after cell division begins, an embryo of the next sporophyte generation. In flowering plants, a second sperm nucleus fuses with other nuclei in the megagametophyte forming a typically polyploid (often triploid) endosperm tissue, which serves as nourishment for the young sporophyte.

Integuments, micropyle, chalaza and hilum

Plant ovules: Gymnosperm ovule on left, angiosperm ovule (inside ovary) on right
Models of different ovules, Botanical Museum Greifswald

An integument is a protective layer of cells surrounding the ovule. Gymnosperms typically have one integument (unitegmic) while angiosperms typically have two integuments (bitegmic). The evolutionary origin of the inner integument (which is integral to the formation of ovules from megasporangia) has been proposed to be by enclosure of a megasporangium by sterile branches (telomes). Elkinsia, a preovulate taxon, has a lobed structure fused to the lower third of the megasporangium, with the lobes extending upwards in a ring around the megasporangium. This might, through fusion between lobes and between the structure and the megasporangium, have produced an integument.

The origin of the second or outer integument has been an area of active contention for some time. The cupules of some extinct taxa have been suggested as the origin of the outer integument. A few angiosperms produce vascular tissue in the outer integument, the orientation of which suggests that the outer surface is morphologically abaxial. This suggests that cupules of the kind produced by the Caytoniales or Glossopteridales may have evolved into the outer integument of angiosperms.

The integuments develop into the seed coat when the ovule matures after fertilization.

The integuments do not enclose the nucellus completely but retain an opening at the apex referred to as the micropyle. The micropyle opening allows the pollen (a male gametophyte) to enter the ovule for fertilization. In gymnosperms (e.g., conifers), the pollen is drawn into the ovule on a drop of fluid that exudes out of the micropyle, the so-called pollination drop mechanism. Subsequently, the micropyle closes. In angiosperms, only a pollen tube enters the micropyle. During germination, the seedling's radicle emerges through the micropyle.

Located opposite from the micropyle is the chalaza where the nucellus is joined to the integuments. Nutrients from the plant travel through the phloem of the vascular system to the funiculus and outer integument and from there apoplastically and symplastically through the chalaza to the nucellus inside the ovule. In chalazogamous plants, the pollen tubes enter the ovule through the chalaza instead of the micropyle opening.

Nucellus, megaspore and perisperm

The nucellus (plural: nucelli) is part of the inner structure of the ovule, forming a layer of diploid (sporophytic) cells immediately inside the integuments. It is structurally and functionally equivalent to the megasporangium. In immature ovules, the nucellus contains a megasporocyte (megaspore mother cell), which undergoes sporogenesis via meiosis. In the megasporocyte of Arabidopsis thaliana, meiosis depends on the expression of genes that facilitate DNA repair and homologous recombination.

In gymnosperms, three of the four haploid spores produced in meiosis typically degenerate, leaving one surviving megaspore inside the nucellus. Among angiosperms, however, a wide range of variation exists in what happens next. The number (and position) of surviving megaspores, the total number of cell divisions, whether nuclear fusions occur, and the final number, position and ploidy of the cells or nuclei all vary. A common pattern of embryo sac development (the Polygonum type maturation pattern) includes a single functional megaspore followed by three rounds of mitosis. In some cases, however, two megaspores survive (for example, in Allium and Endymion). In some cases all four megaspores survive, for example in the Fritillaria type of development (illustrated by Lilium in the figure) there is no separation of the megaspores following meiosis, then the nuclei fuse to form a triploid nucleus and a haploid nucleus. The subsequent arrangement of cells is similar to the Polygonum pattern, but the ploidy of the nuclei is different.

After fertilization, the nucellus may develop into the perisperm that feeds the embryo. In some plants, the diploid tissue of the nucellus can give rise to the embryo within the seed through a mechanism of asexual reproduction called nucellar embryony.

Megagametophyte

Megagametophyte formation of the genera Polygonum and Lilium. Triploid nuclei are shown as ellipses with three white dots. The first three columns show the meiosis of the megaspore, followed by 1-2 mitoses.
Ovule with megagametophyte: egg cell (yellow), synergids (orange), central cell with two polar nuclei (bright green), and antipodals (dark green)

The haploid megaspore inside the nucellus gives rise to the female gametophyte, called the megagametophyte.

In gymnosperms, the megagametophyte consists of around 2000 nuclei and forms archegonia, which produce egg cells for fertilization.

In flowering plants, the megagametophyte (also referred to as the embryo sac) is much smaller and typically consists of only seven cells and eight nuclei. This type of megagametophyte develops from the megaspore through three rounds of mitotic divisions. The cell closest to the micropyle opening of the integuments differentiates into the egg cell, with two synergid cells by its side that are involved in the production of signals that guide the pollen tube. Three antipodal cells form on the opposite (chalazal) end of the ovule and later degenerate. The large central cell of the embryo sac contains two polar nuclei.

Zygote, embryo and endosperm

The pollen tube releases two sperm nuclei into the ovule. In gymnosperms, fertilization occurs within the archegonia produced by the female gametophyte. While it is possible that several egg cells are present and fertilized, typically only one zygote will develop into a mature embryo as the resources within the seed are limited.

In flowering plants, one sperm nucleus fuses with the egg cell to produce a zygote, the other fuses with the two polar nuclei of the central cell to give rise to the polyploid (typically triploid) endosperm. This double fertilization is unique to flowering plants, although in some other groups the second sperm cell does fuse with another cell in the megagametophyte to produce a second embryo. The plant stores nutrients such as starch, proteins, and oils in the endosperm as a food source for the developing embryo and seedling, serving a similar function to the yolk of animal eggs. The endosperm is also called the albumen of the seed. the zygote then develops into a megasporophyte, which in turn produces one or more megasporangia. The ovule, with the developing megasporophyte, may be described as either tenuinucellate or crassinucellate. The former has either no cells or a single cell layer between the megasporophyte and the epidermal cells, while the latter has multiple cell layers between.

Embryos may be described by a number of terms including Linear (embryos have axile placentation and are longer than broad), or rudimentary (embryos are basal in which the embryo is tiny in relation to the endosperm).

Types of gametophytes

Megagametophytes of flowering plants may be described according to the number of megaspores developing, as either monosporic, bisporic, or tetrasporic.

Operator (computer programming)

From Wikipedia, the free encyclopedia https://en.wikipedia.org/wiki/Operator_(computer_programmin...