Question

Explain what effect a lack of functional androgen receptors would have on the development of the reproductive system of a chromosomally XY fetus. Assume sry is present. Your answer should address the development of the gonads, internal reproductive system and genitalia.

Answer 1

SRY gene influence the type of gonads. Of SRY gene is present, then gonads will be testis. If not, the gonads will be ovaries.

Testis has two cells: Sertoli cells and Leydig cells. Sertoli cells secrete Anti-Mullerian hormone which causes regression of Mullerian duct which forms female internal genitalia. Leydig cells secrete testosterone around 8 weeks of intrauterine life. Testosterone has two functions:

• It promotes growth of Wolffian duct which forms male internal genitalia (seminal vesicles, epididymis, ejaculatory duct, vas deferens).
• It is converted into Dihydrotestosterone which is responsible for formation of male external genitalia.

If testosterone receptors are not functional, then testosterone cannot perform its actions. Therefore, male internal genitalia will not be formed. It will not be female's because Mullerian duct was inhibited by Anti-Mullerian hormone. Dihydrotestosterone will not be formed which results in non-formation of male external genitalia. Instead, the external genitalia will resemble female external genitalia. This is called Ambiguous genitalia (sex of the baby cannot be determined by seeing the external genitalia).

Gonads: Testis (determined by SRY gene only)

Internal genitalia: Not formed (Also not female's)

External genitalia: Resembles female's.