Here's a question I thought someone could help out with.
In Congenital Adrenal Hyperplasia, increased androgen (DHT) levels cause masculinization of the external genitalia but the Wolffian ducts still regress. Why woulnd't internal genitalia also persist?
Thanks for the help!
Wolf
MANian ducts are dude structures
Mullerian ducts are chick structures
When a dude becomes a dude, the presence of a Y chromosome leads to release of Anti-Mullerian Hormone, which suprisingly, murders the mullerian ducts (the stuff that becomes the uterus, the fallopian tubes, and the upper third of the vagina).
To become a dude, you have to get rid of the chick stuff. Thats done with
Anti-Mullerian Hormone.
When a dude becomes a dude, the Y chromosome says to make Testosterone, specifically 5-HT Testosterone. This stuff makes the external genitalia into a penis and scrotum.
To become a dude, you have to change the chick stuff to a dude stuff. Thats done with
testosterone.
With CAH, what's happening? The body is all like "ZOMGS! NEED MORE CORTISOLS! NEED MORE ALDOSTERONES!" So the signal goes crazy to the adrenals. The adrenals, listening to the signal, try to make cortisol and aldosterone. But it can't. The enzyme required to go down that pathway is broken. So what happens to all that cholesterol that SHOULD have become cortisol or aldosterone? It gets shunted down the testosterone pathway. What's the
adrenal testosterone form? Right.
DHEA.
So in CAH, whether you're a chick or a dude, you're making too much testosterone. Don't worry about which type it is, just understand testosterone = dude on the outside. DHEA, Testosterone, DHT, 5-HT, blibbity blah. Testosterone = dude on the outside.
So dudes have Anti-Mullerian + Testosterone + EXTRA testosterone (no mullerian structures and big balls, big penis).
And chicks have EXTRA testosterone (yes mullerian structures, and masculinization of the external genitalia). Not as much masculinization as if there were a Y chromosome, but you get cliteromegaly (big clitoris) and potentially fusion of the labia, labia trying to become a scrotum.
So to answer your original question:
Testosterone has nothing to do with internal structures, its the presence of Anti-Mullerian Hormone to kill mullerian that decide what you are on the inside
I'm not 100% positive, but I believe the internal genitalia is dependent on the presence of the Y chromosome. In its absence, the SRY gene will not produce testis-determining-factor (product of the SRY gene), and Mullerian inhibitory hormone. As a result, the mullerian ducts will be created as default. The external genitalia appears ambiguous because of the increased androgens resulting in part of the synthetic pathway (ie. 21 hydroxylase). This would lead to alterations that could cause the appearance of male external genitalia.
And to the above poster, you are correct sir...:
Y chromosome --> SRY gene --> Testes Determining Factor --> Anti-Mullerian Hormones AND Testosterone
