Between XX and XY: Intersexuality and the myth of two sexes

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Unformatted text preview: an arise when a mutation destroys portions of the SRY. These individuals, also 46,XY, also develop into baby girls. One example of this sort of change results in complete gonadal dysgenesis. A gene known as “desert hedgehog” lies in the SRY region of the Y chromosomes. Desert hedgehog is a member of a gene family that includes sonic hedgehog and Indian hedgehog—all of which play key roles during early pattern formation in the developing embryo. When desert hedgehog fails to do its job, 46,XY fetuses develop normal vaginas and uteruses but only streak gonads. At puberty, these people do not develop female secondary sex characteristics.10 Clearly the genes within SRY play major roles in the development of male babies. Interestingly, though, only about 15 percent of 46,XY females appear to arise from loss of or mutations in the SRY. So SRY is only part of the story—a necessary but not sufficient piece along the twisted path to boyhood. On occasion, a man’s X chromosome will find that piece of Y chromosome left behind in the nucleus, then pick it up and stick it in an empty pocket. That bit of greediness creates an X chromosome carrying the SRY. When a sperm with that X chromosome hooks up with an ovum carrying the usual X chromosome, then the zygote, embryo, fetus, and child will have a 46,XX karyotype. But it will enter this world as a baby boy, or almost. Even though everything looks boyish at birth, as adults, these people are sterile and generally have smaller than normal testes.11 Otherwise, they are pretty much just like 46,XY people. True hermaphrodites To zoologists and botanists, true hermaphrodites are animals or plants that can play the role of either male or female, sometimes even both, during sexual reproduction. The ones we are most familiar with, like hermaphroditic trees, can even fertilize their own ova. By those terms, there is clearly no such thing as a true human hermaphrodite. Regardless, there is a group of human beings that reproductive biologists call true hermaphrodites. By definition, a true human hermaph- Where Our Sexes Come From 77 rodite must have both ovarian and testicular tissues either in the same or different gonads. Because of the inaccuracy of the word hermaphrodite in reference to human beings, scientists have recently suggested that we refer to these people as persons with ovotesticular disorders of sexual development. Because of its historical significance, however, in this chapter I will stick with hermaphrodite. The most common karyotype among true hermaphrodites is 46,XX (one of these X chromosomes usually has the SRY it collected from a Y chromosome) followed by 46,XX/46XY chimeras or mosaics, and only rarely 46,XY. On the outside, these people may look like males or females or something in between. Almost all of them, though, are raised as males because they have enlarged phalluses. Those phalluses—even if they began as clitorises—grow to nearly penis proportions because of the testosterone made by testicular tissue, always a part of a “true” hermaphrodite. Vaginas and uteruses are present in the majority of these people, and usually at least one testis is palpable in the labioscrotal fold (that is, one testis has descended into what is a mixture of scrotum and labium). Breast development occurs with most true hermaphrodites at puberty, as does menstruation because of the ovarian tissue. But very few true hermaphrodites produce sperm. Ovulation, though, is common, and many true hermaphrodites with 46,XY karyotype are fertile and have borne children. For most people the cause of their hermaphroditism never becomes clear. Several possibilities exist: sex chromosome chimerism and mosaicism are among the leading possibilities. In either of these cases, one of the gonads could be 46,XX and the other 46,XY; or individual gonads could contain cells with both karyotypes. Alternatively, if the SRY region of the Y chromosome was picked up by another sex chromosome or even a chromosome other than X or Y, SRY could create a similar situation with cells of two different karyotypes appearing in one or both gonads. Regardless, by their position in the middle, true hermaphrodites reveal to us the full array of the human spectrum lying in between the 78 Between XX and XY unattainable ideals of the perfect male and the perfect female, between XX and XY. Lisa May Stevens Age: 42 Location: Idaho, USA “The nasty, nasty crows are so very cruel to her, just because she is so very different . . .” —from one of Lisa May’s poems “Mother was a little strange at best,” says Lisa May Stevens. “When I was between five and six years old . . . she would call me to her room, strip me naked, and begin to dress me in my ‘Lisa May’ clothes. If I objected, she would pull my dress up and spank me.” At the time, Lisa May’s name was actually Michael. Lisa May was his grandmother’s name, but at age five, Michael had no idea why his mother called him that. At first, Michael resisted th...
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This document was uploaded on 02/04/2014.

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