Male Reproductive Endocrinology

Question 1

What are the two major functions of the gonads?

Answer 1

(1) Produce gametes

(2) Produce hormones for the development of secondary sex characteristics

Question 2

The __________ in males and the ________ in females have LH recepotrs and produce ______________.

Answer 2

Leydig; thecal; androgens (mainly testosterone)

Question 3

The ____________ in males and the __________ in females have FSH receptors and produce _____________.

Answer 3

Sertoli; granulose; inhibin

Question 4

The ____________ cells take testosterone and produce estrogen.

Answer 4

Sertoli and granulose

Question 5

The _____________ cells (provide the male and female) serve as a barrier between the bloodstream and the developing gametes.

Answer 5

supporting –Sertoli and granulose –

Question 6

The number of functioning ________________ determines the maximum rate of sperm production.

Answer 6

Sertoli cells (defects in Sertoli cells are a common cause of infertility)

Question 7

Again, what is the rate-limiting step in the synthesis of androgens?

Answer 7

Cholesterol -> pregnenolone (catalyzed by 20,22-desmolase)

Question 8

What reactions are catalyzed by 5-alpha reductase and aromatase?

Answer 8

5AR: testosterone to dihydrotestosterone
Aromatase: testosterone to estradiol

Question 9

Most circulating testosterone is bound to ________________.

Answer 9

sex-hormone binding globulin

Question 10

Testosterone binds to the _____________ receptor.

Answer 10

androgen

Question 11

Where is the androgen receptor located?

Answer 11

It is ubiquitous, but found at the highest concentrations in the muscle and reproductive tissues.

Question 12

Which parts of the male genitalia need DHT?

Answer 12

The external genitalia. A man born with 5-alpha reductase deficiency will have normal testes and seminiferous tubules at birth but a small penis.

Question 13

Describe the molecular structure of LH and FSH and the high yield association you might get tested on.

Answer 13

LH and FSH are heterodimers with an alpha and beta subunit. The alpha unit is identical and is shared with TSH and hCG, but the beta subunit confers specificity.

Question 14

The beta subunit of LH is very similar to ___________.

Answer 14

hCG (so hCG is often used as a therapeutic substitute for LH)

Question 15

What kind of receptor is the GnRH receptor?

Answer 15

GPCR

Question 16

Daily doses of GnRH analogs lead to _____________.

Answer 16

inhibition of the effects of GnRH (so infertility)

Note: normal secretion is hourly pulses and leads to profertile response