Intersexuality

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An intersexual or intersex person (or organism of any unisexual species) is one who is born with genitalia and/or secondary sex characteristics determined as neither exclusively male nor female, or which combine features of the male and female sexes. The terms hermaphrodite and pseudohermaphrodite, introduced in the 19th century, are now considered misleading and stigmatizing, and patient advocates call for these terms to be abandoned. There is also a move to drop the term "intersex", replacing it with "Disorders of Sex Development" (DSD). The phrase "ambiguous genitalia" refers specifically to genital appearance, but not all intersex conditions result in atypical genital appearance.

1 Overview
2 Biological causes of intersexuality
3 Chimerism
4 Intersexuals in society
5 See also
6 References
7 External links

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Overview

According to the highest estimates (Fausto-Sterling et. al., 2000) perhaps 1 percent of live births exhibit some degree of sexual ambiguity [1], and that between 0.1% and 0.2% of live births are ambiguous enough to become the subject of specialist medical attention, including surgery to disguise their sexual ambiguity. Other sources (Leonard Sax, 2002) create a narrower definition of "true intersexual conditions" and estimate the incidence as far lower, at approximately 0.018%.

In typical fetal development, the presence of the SRY gene causes the fetal gonads to become testes; the absence of it allows the gonads to continue to develop into ovaries. Thereafter, the development of the internal reproductive organs and the external genitalia is determined by hormones produced by certain fetal gonads (ovaries or testes) and the cells' response to them. The initial appearance of the fetal genitalia (a few weeks after conception) is basically feminine: a pair of "urogenital folds" with a small protuberance in the middle, and the urethra behind the protuberance. If the fetus has testes, and if the testes produce testosterone, and if the cells of the genitals respond to the testosterone, the outer urogenital folds swell and fuse in the midline to produce the scrotum; the protuberance grows larger and straighter to form the penis; the inner urogenital swellings grow, wrap around the penis, and fuse in the midline to form the penile urethra.

Because there is variation in all of these processes, a child can be born with a sexual anatomy that is typically female, or feminine in appearance with a larger than average clitoris; or typically male, masculine in appearance with a smaller than average penis that is open along the underside. The appearance may be quite ambiguous, describable as female genitals with a very large clitoris and partially fused labia, or as male genitals with a very small penis, completely open along the midline ("hypospadic"), and empty scrotum.

There are dozens of named medical conditions that may lead to intersex anatomy. Fertility is variable. The distinctions "male pseudohermaphrodite", "female pseudohermaphrodite" and especially "true hermaphrodite" are vestiges of 19th century thinking that placed "true sex" in the histology (microscopic appearance) of the gonads.

The common habit in the 21st century of elevating the role of the sex chromosomes above all other factors when determining gender may be analogous to the older habit of finding "true" sex in the gonads. Though high school biology teaches that men have XY and women XX chromosomes, in fact there are quite a few other possible combinations such as Turner syndrome XO, Metafemale syndrome XXX, Klinefelter's syndrome XXY, Jacob's syndrome XYY, Mosaicism XO/XY, de la Chapelle syndrome XX male, Swyer syndrome XY female, and there are many other individuals who do not follow the typical patterns (such as individuals with four or even more sex chromosomes).

Thus, people nowadays may be more likely to look towards the sex chromosomes than, for example, the histology of the gonads. However, according to researcher Eric Vilain at the University of California, Los Angeles, "the biology of gender is far more complicated than XX or XY chromosomes".[2] Many different criteria have been proposed, and there is little consensus.[3]

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Biological causes of intersexuality

Typical males have sex chromosomes XY and typical females XX. One biological definition of a male child is the presence of a Y chromosome. This definition has sometimes been used for sex determination at sports events, but it caused much confusion because it does not always apply.

The most common cause of sexual ambiguity is congenital adrenal hyperplasia, an endocrine disorder in which the adrenal glands produce abnormally high levels of virilizing hormones. In genetic females, this leads to an appearance that may be slightly masculinized (large clitoris) to quite masculine.

In many cases individuals are neither XX nor XY:

The presence of one or two additional X chromosomes in a male (XXY or XXXY) may cause Klinefelter's syndrome.

A single X chromosome (XO) is called Turner's syndrome. It is characterized by a lack or incomplete development of certain primary and secondary female characteristics and is associated with a range of medical issues.

Sex chromosomal mosaicism or chimerism can cause what was once called "true hermaphroditism", the presence of both testicular and ovarian tissue in one individual.

In Persistent mullerian duct syndrome the child has XY chromosomes typical of a male. The child has a male body and an internal uterus and fallopian tubes because his body did not produce Mullerian inhibiting factor during fetal development.

The following further XY cases leads to intersexuality:

Androgen insensitivity syndrome. They develop either partially or fully as females, due to their bodies failing to respond to testosterone. In the case of complete androgen insensitivity syndrome (CAIS), their tissues are totally insensitive to androgens, and they will develop as females, with normal female external organs. However, they will not develop a uterus or fallopian tubes, due to the production of Mullerian inhibiting factor by their testes. At puberty breasts will develop due to the production of estrogen by the testes; but no menstruation will occur due to the lack of a uterus. The tissues of individuals with partial androgen insensitivity, by contrast, have partial sensitivity to testosterone, but it is reduced compared to the male normal. These individuals can develop with either male external anatomy, or female external anatomy, or some combination, depending on the degree of insensitivity.

5-alpha-reductase deficiency. In this condition, individuals have testes, as well as vagina and labia, but with a small penis capable of ejaculation instead of a clitoris (this penis, however, appears to be a clitoris at birth). These individuals are normally raised as girls. However, come puberty, their testes will descend, their voice will deepen and they often will develop a male sexual identity. But they develop only limited facial hair. The number of people with this condition varies geographically, depending on how much of a given population is interrelated.

Excessive in utero exposure to androgens may lead to intersexuality in XX cases:

Congenital adrenal hyperplasia: Female internal anatomy, but ambiguous or male external genitalia, and develop male secondary sexual characteristics.

Progestin-induced virilisation. In this case, the male hormones are caused by use of progestin, a drug that was used in the 1950s and 1960s in order to prevent miscarriage. These individuals have internal and external female anatomy. They develop however some male secondary characteristics, and they frequently have unusually large clitorises.

A similar phenomenon occurs in cases where a cow brings two fraternal twins, one male and one female, to term. Because (unlike humans) such twins share hormones via their placental blood interface with the mother cow, male hormones produced in the body of the fetal bull find their way into the body of the fetal cow and masculinize her brain. The result is a freemartin (unconventional heifer), a cow that will eventually try to mount other cows the way that a bull would.

In XX male syndrome (also called de la Chapelle syndrome) the resulting child is usually a phenotypically normal male, but without sperm production. This syndrome is sometimes the result of an abnormal interchange of the SRY region from a Y chromosome to an X.

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Chimerism

According to the New England Journal of Medicine, vol 338, p 166, physicians in the Western General Hospital of Edinburgh have reported on a child with a penis, one testicle, and an ovary and fallopian tube instead of a second testicle. Some of this child's body cells are XY (male), and some are XX (female). The child was conceived as the result of in-vitro fertilization, and it appears most likely that two embryos, a male embryo and a female embryo, fused before or soon after embryos were transferred to the mother's uterus.

This kind of condition, where there is more than one set of cell lines with different sets of chromosomes making up the body is known as chimerism. This kind of tetraploid chimerism can also occur naturally, without in-vitro fertilization (see New England Journal of Medicine, vol 346, p 1545).

Not all cases of Chimerism involve intersexuality, however. There have been about 40 known cases worldwide of humans reproducing naturally and producing offspring with absolutely no genetic similarities between mother and child. Discovery Health Channel has produced a documentary on two families and their issues in dealing with chimerism. It was called "I Am My Own Twin."

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Intersexuals in society

Intersexual individuals are treated in different ways by different cultures. In some cultures intersexuals were included in larger "third gender" or gender-blending social roles along with other individuals. In most societies, intersexed individuals have been expected to select one sex, and conform to its gender role.

Since the rise of modern medical science in Western societies, intersexuals with ambiguous external genitalia have had their genitalia surgically modified to resemble either male or female genitals. But there are increasing calls for recognition of the various degrees of intersexuality as healthy variations which should not be subject to correction. Some have attacked the common Western practice of performing corrective surgery on the genitals of intersexuals as a Western cultural equivalent of female genital mutilation. Despite the attacks on the practice, most of the medical profession still supports it. Others have claimed that the talk about third sexes represents an ideological agenda to deride gender as a social construct whereas they believe gender is a biological reality.

Corrective surgery is generally not necessary for protection of life or health, but purely for aesthetic or social purposes. Unlike other aesthetic surgical procedures performed on infants, such as corrective surgery for a cleft palate, genital surgery may lead to negative consequences for sexual functioning in later life (such as loss of sensation in the genitals) which would have been avoided without the surgery; in other cases negative consequences may be avoided by surgery. Defenders of the practice argue that it is necessary for individuals to be clearly identified as male or female in order for them to function socially. However, many intersex individuals have resented the medical intervention, and some have been so discontented with their surgically assigned gender as to opt for sexual reassignment surgery later in life.

The writer Anne Fausto-Sterling coined the words herm (for hermaphrodite), merm (for an intersex person that most closely resembles a male), and ferm (for an intersex person that most closely resembles a female), and proposed that these be recognized as sexes along with male and female. However, her use was "tongue-in-cheek"; she no longer advocates these terms even as a rhetorical device.

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References

Blackless, Melanie, Anthony Charuvastra, Amanda Derryck, Anne Fausto-Sterling, Karl Lauzanne, and Ellen Lee. 2000. How sexually dimorphic are we? Review and synthesis. American Journal of Human Biology 12:151-166.
Dreifus, Claudia. "A Conversation with Anne Fausto-Sterling" The New York Times. 2 January 2001 (p. F3).
Heard, Alex. "Out There: Everything But the Truth" The Washington Post Magazine. 4 September 1988 (p. W9).
Musto, Michael. "La Dolce Musto". The Village Voice. 22 September 1998 (p. 12).
Sax, Leonard. How common is intersex? A response to Anne Fausto-Sterling. J Sex Research 39:174-9, 2002
(2004) The Evolution of Self-Fertile Hermaphroditism: The Fog Is Clearing. PLoS Biol 3(1): e30.