Question

A) How would the development of the testes in a chromosomally XY rat embryo be affected by exposure to very high levels of estradiol?

Select one:

a. It would develop ovotestes, gonads that consist of a combination of testicular and ovarian tissues

b. It would develop testes

c. Gonadal development would be stopped

B) You treat a chromosomally XY rat fetus early in development with a combination of an androgen receptor antagonist and an MIS receptor antagonist. What internal reproductive organs would it develop? Check all the correct answers.

a. Fallopian tubes

b. Ovaries

c. Testes

d. Uterus

e. Seminal vesicles

f. Cervix

g. Seminal vesicles

h. Vas deferens

C) What internal reproductive organs would develop in a female rat pup (chromosomally XX) if you treated her with MIS during early embryonic development? Check all the correct answers.

Select one or more:

a. Vas deferens

b. Ovaries

c. Epididymis

d. Cervix

e. Uterus

D) Development of which of the following tissues in an embryo is affected by DHT levels? Check all the correct options.

a. Genital tubercle

b. Mullerian ducts

c. Gonads

d. Wolffian ducts

e. labioscrotal swellings

Answer 1

A) It would develop testes

Development of gonads is strictly genetic and cannot be affected by hormone altertion. Since SRY gene on Y chromosome encodes testis determining factor, male sexual differentiation and testis development takes place.

B)

• Fallopian tubes
• Testes
• Uterus
• Cervix

Both androgen and MIS (Mullerian Inhibiting Substance) are involved in development of male reproductive structures and hence their inhibition alters development of reproductive structures. Androgen antagonism affects development of male structures whereas MIS antagonism promotes development of female reproductive tract from mullerian duct. Since gonad development is strictly genetic, testes development takes place as the rat fetus is chromosomally XY.

C) Ovaries

As gonad development is strictly genetic, chromosomally XX rat pup will develop ovaries. But, as MIS is administered, female reproductive tract development from mullerian duct will not take place.

D)

• Genital tubercle
• Wolfian ducts
• Labioscotal swellings

Genital tubercle is sensitive to DHT which causes its development to glans penis. Exposure of Wolffian duct to DHT causes their development into connected system of epididymis, vas deferens and seminal vesicle. DHT facilitates development of labioscrotal swelling to scrotum.