出典(authority):フリー百科事典『ウィキペディア(Wikipedia)』「2012/11/10 13:04:28」(JST)
Pseudohermaphroditism | |
---|---|
Classification and external resources | |
ICD-10 | Q56.1-Q56.3 |
ICD-9 | 752.7 |
DiseasesDB | 14836 14839 |
MeSH | D012734 |
Pseudohermaphroditism, or pseudo-hermaphroditism, is the condition in which an organism is born with secondary sex characteristics[1] or a phenotype[2] that is different from what would be expected on the basis of the gonadal tissue (ovary or testis).
In some cases, the external sex organs look intermediate between the typical clitoris or penis. In other cases, the external sex organs have an appearance that does not look intermediate, but rather has the appearance that would be expected to be seen with the "opposite" gonadal tissue. Because of this, pseudohermaphroditism is sometimes not identified until puberty. It is possible for the condition to be undetected until adulthood.[3]
The term "male pseudohermaphrodite" is used when a testis is present, and the term "female pseudohermaphrodite" is used when an ovary is present.[4] The term "true" hermaphrodite is reserved for the very rare cases where both ovarian and testicular tissue is present. (Whether or not that term would be appropriate when ovotestes are found, or only when distinct ovaries and testes are found, is not well defined.)
Associated conditions in males include 5-α-reductase deficiency[5] from a deficiency in the male chromosome (46 XY).[6][7]
Contents
|
Surgery has sometimes been performed to alter the appearance of the genitals.[8][9]
Use of the term "pseudohermaphroditism" can be problematic, and is now considered redundant.[10] The term "pseudohermaphroditism" was created by Edwin Klebs in 1876,[11][12] long before the genetic roles of the X chromosome and Y chromosome and the social components of gender identity were well characterized, which is why the term is usually used to describe the dissonance between gonadal histology and external genital appearance.
The term "intersexuality" was introduced by Richard Goldschmidt in 1923.[11][13] However, the term "intersex" has also been challenged; the Lawson Wilkins Pediatric Endocrine Society and the European Society for Pediatric Endocrinology have adopted a nomenclature system based on disorders of sex development, which covers "congenital conditions in which development of chromosomal, gonadal, or anatomical sex is atypical" and thus replaces many disparate terms, including but not limited to those based on "hermaphrodite."[10][14]
One example of the challenges involved in the use of the term is the case of women with Complete Androgen Insensitivity Syndrome (CAIS). These women often have primary and secondary sexual characteristics typical of other women; however, they are genetically XY and have internal testes, rather than ovaries. They have the same likelihood of a genetically XX woman of enjoying sexual pleasure but are unable to biologically reproduce. Their sexuality (homosexual, heterosexual, bisexual etc.) is unrelated to this syndrome. However scientifically precise the description "male" pseudohermaphrodite may be for such women, it is clearly socially inappropriate. CAIS is considered little better by some, as the S for syndrome in CAIS does not accord with the "normality" many CAIS women feel about their bodies.
In human beings, the sex status is defined at four levels: chromosomal (XY; XX), internal organs (ovaries; testicles), external organs (breasts, vulva + vagina; penis), and psyche (sexual identity). In a XX human the default development process results in a female. In a XY human a set of genes on the Y chromosome trigger a cascade of events normally resulting in a male. A complete female or male developmental process entails the expression of female and male sex hormones, respectively, and of their corresponding receptors in the target tissues. Without these hormones and their receptors, the internal and external sex organs, and psyche, will not develop as expected. Sex hormones, their receptors, and downstream signal transduction proteins are coded by genes that may be genetically defective.
All these factors mean that genetic mutations can block the sexual development process at three stages: (a) before the development of the internal sex organs; (b) after the development of the internal sex organs but before the development of external sex organs; and (c) after the development of external sex organs but before the maturation of the sexual component of the psyche.
While in (a) the XY human will be indistinguishable anatomically and psychologically from a female; in (b) the individual may either be born with ambiguous external genitals or have genitals apparently in the normal range at birth but, at pubertal age, not develop secondary sexual characteristics at all or develop secondary sexual characteristics that do not match the external genitals; and in (c) the individual will be transgendered (formerly referred to as transsexual).
There are other intersexual states that are not the result of the genetic configurations above.
In particular, where either the individual is a chimera - resulting from a fusion of two distinct embryos, one male and one female, during fetal development (not a genetic mosaic), or the individual contains duplicated chromosomes in the genome (XXY; XXXY). In the former case some tissues will be in the XX and others in the XY configuration; in the latter, all cells contain the Y chromosome and may or may not use it. This is a gynandromorph, which has both female and male characteristics at all four levels and may have either ambiguous sex organs (the XY/XX configuration may not be evenly distributed throughout the body) or unambiguous male and female sex organs (hermaphrodite).
John Money is perhaps the best-known early researcher in this area. His doctoral thesis was titled Hermaphroditism: An Inquiry into the Nature of a Human Paradox, and awarded by Harvard University in 1952.[15]
Money's general views on gender identity as something learned during childhood were later directly contradicted by a biography published in 2001 by one of his former patients, David Reimer. Among the repercussions was damage to John Money's reputation. Not only had his theory of gender plasticity been dealt a severe blow but Reimer's biography described bizarrely unpleasant childhood therapy sessions, and implied that Money had ignored or concealed the developing evidence that Reimer's reassignment to female was not going well. Money's defenders have suggested that some of the allegations about the therapy sessions may have been the result of False memory syndrome. However, Reimer's brother and mother both agreed that the therapy was not "working" in the sense that Reimer wasn't in any way developing a female self-image during his treatment with Dr. Money. Dr. Money never publicly stated that his conclusions were incorrect.
Milton Diamond has probably become the best known expert public advocate for the intersex community in the early 21st century. He is the director of the Pacific Center for Sex and Society.[16]
|
|
全文を閲覧するには購読必要です。 To read the full text you will need to subscribe.
リンク元 | 「仮性半陰陽」「偽雌雄同体」 |
拡張検索 | 「male pseudohermaphroditism」「female pseudohermaphroditism」 |
.