Gender:  In the Genes or in the Jeans?

Section B

Experimental work on laboratory animals showed that testosterone treatment of XX fetuses causes them to develop male genitals. Although we cannot ethically perform such experiments on human fetuses, there are some naturally occurring situations that support this hypothesis in humans too. In some extremely rare cases, pregnant women were found to have a testosterone-secreting tumor and their XX offspring were born with male genitals. The general consensus was that prenatal testosterone causes male genital differentiation.

This idea was modified in the 1970s, when some people were described with an unusual condition. At birth, their genitals were..., well, it was hard to tell. Their families lived in a small village, far from medical facilities, and since the babies sort of looked like girls, they were raised as girls. They went through puberty at around the usual age, but they didn’t menstruate and develop breasts. Rather, it was their muscles that developed, voices deepened, and what had looked like a clitoris began to enlarge and appear more like a penis. In short, at puberty, these "girls" began to look more and more like adult males, and began to behave in ways typical of males in that village, including marrying a woman.

When they reached the attention of the medical community, the condition could be described medically as follows: XY chromosome, testes (which were undescended, so not noticeable), Wolffian duct development, no Mullerian duct, and blood levels of testosterone similar to that of a typical male. Very much like normal males! Just one small difference was noted. They lacked an enzyme called 5-alpha reductase, which converts testosterone to a related molecule, dihydrotestosterone, or DHT.

Questions

1. What would you now conclude about the differentiation of the male genitals?
    
2. Revise your flowchart to indicate the process of differentiation of the genitals.

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