2-6 DSA Male Hormones in Development and Reproduction

Question 1

How do GnRh levels change over time? (In males, this whole card deck is obviously a sausage fest.)

Answer 1

Typically tends to have tonic release in males

Question 2

What is the source of sec steroid production in the testes?

Answer 2

Leydig cells

Question 3

What promotes early increase in number of Leydig cells?

Answer 3

maternal hCG - up to 26 weeks

fetal LH

Question 4

What happens, generally, when androgen receptors are absent?

Answer 4

sexual ambiguity

Question 5

What kind of receptor is an androgen receptor?

Answer 5

homodimer nuclear receptor

- trx factor, binds hormone response elements

Question 6

What enzyme converts testosterone to DHT?

Answer 6

5-alpha-reductase

Question 7

How is DHT functionally different from testosterone in peripheral tissues?

Answer 7

DHT binds receptor with affinity ~100x higher than testosterone

DHT-receptor binds chromatin more tightly

Question 8

What makes MIS?

Answer 8

Sertoli cells

MIS = antimullerian hormone

Question 9

What 2 major roles do androgens play in development of the male phenotype?

Answer 9

1. trigger conversion of the wolffian ducts to ejaculatory system
2. direct differentiation of the urogenital sinus and external genitalia

Question 10

What male genital developmental processes depend on testosterone? DHT?

Answer 10

testosterone - wolffian phase, wolffian duct lack 5-alpha-reductase

DHT - virilization of the urogenital sinus, prostate, penile urethra, and external genitalia during embryogenesis
- also req. for puberty

Question 11

What is an important protein secreted by Sertoli cells? Why is it important?

Answer 11

Androgen Binding Protein

Creates high local levels of testosterone

• stimulates medulla of gonad to differentiate into rete testes,
• stimulates wolffian duct to differentiate into epididymis, vas deferens, seminal vesicles, and ejaculatory duct
• promotes development of prostate

Question 12

What is congenital adrenal hyperplasia?

Answer 12

Ambiguous genitalia in females from missing enzymes in adrenal cortex
- most often 21-alpha-hydroxylase

Question 13

What is male pseudohermaphroditism?

Answer 13

Any defect in the way androgens act on target tissues

affected have 46 XY genotype and unambiguous male gonads but ambiguous external genitalia