Question

Please explain what effect a lack of functional androgen receptors would have on the development of the reproductive system of a chromosomally XY fetus. Assume that sry is present. The explanation should include the development of the gonads, internal reproductive system, and genitalia.

Answer 1

If SRY gene is present, then the fetus will be XY ie male and its gonads will be testis. Testis has two cells: Sertoli cells and Leydig cells. Sertoli cells at around 7 weeks of intrauterine life secrete Anti-Mullerian hormone which causes regression of Mullerian duct and hence the genital tract will not be female's. Leydig cells at around 8 weeks start secreting Testosterone. Testosterone promotes the growth of Wolffian duct which forms male internal genitalia (seminal vesicles, epididymis, ejaculatory duct, vas deferens) and is converted into Dihydrotestosterone which is responsible for formation of male external genitalia.

When functional testosterone receptors are less, then the testosterone cannot produce its action. Therefore actions of testosterone like promotion of growth of Wolffian duct will not occur leading to Formation of seminal vesicles, epididymis, ejaculatory duct and vas deferens. Also there won't be any conversion to Dihydrotestosterone and hence external genitalia will not look like male , instead it will look like female. This is called Ambiguous genitalia (by looking at external genitalia, sex of the baby cannot be determined).

Gonads: Normal testis as testis is formed from the medulla of the genital ridge which is determined by only SRY gene which is present.

Internal reproductive system: Not developed, as internal genital organs is formed by wolffian duct which requires a functional testosterone.

Genitalia (External): Look like females. (Ambiguous genitalia)