Lecture 20 - Male Reproductive Physiology

Question 1

SRY gene

Answer 1

Sex determining region of the Y (aka TDF - testes determining factor)

transcription factor

needed for XY

Question 2

AMH

Answer 2

anti-mullerian hormone - growth factor –regression of mullerian ducts

blocks progression to female pathway

Question 3

Sertolic Cells

Answer 3

Make AMH

Question 4

Leydig Cells

Answer 4

make testosterone

responsible for internal genitalia

Question 5

DHT

Answer 5

external male genitalia

Question 6

XO

Answer 6

gonadal dysgenesis - Turner’s Syndrome

Question 7

YO

Answer 7

lethal

Question 8

XXY

Answer 8

Klinefelters syndrome

gynecomastia
small testes, reduced fertility

Question 9

Female pseudohermaphroditism

Answer 9

male gender identity

made too much androgen

Question 10

Male pseudohermeaphroditism

Answer 10

female gender identity

male that had androgen resistance

Question 11

When clinically does puberty start?

Answer 11

pulsatile GnRH secretion

Question 12

LH

Answer 12

Leydig cells

stimulate testosterone synthesis and release (in response in GnRH)

Question 13

FSH

Answer 13

sertoli cells

androgen binding protein (ABP)

inhibin synthesis

Question 14

inhibin

Answer 14

hormones made in Sertoli cells responding to FSH

inhibits pituitary production and release of FSH

Question 15

Activin

Answer 15

antagonizes inhibin at pituitary

enhances FSH secretion

Question 16

17Beta hydroxysteroid dehydrogenase

Answer 16

enzyme in the testes that converts pregnenolone or androstenedione to testosterone

Question 17

Where is cholesterol made?

Answer 17

liver

Question 18

What does testosterone do?

Answer 18

1) activates androgen receptor
2) conversion of DHT by 5 alpha reductase
3) Conversion to estradiol by aromatase (CYP19)

Question 19

What are the effects on men who do not response to estradiol?

Answer 19

either from aromatase defect of lack of estrogen receptor

epiphyses does not fuse and osteoporosis

if aromatase defect –treat with estradiol

Question 20

What is testosterone bound to in circulation?

Answer 20

SHBG (sex hormone binding globulin - from liver)

only free T is active

Question 21

Finasteride

Answer 21

competitive inhibitor of 5 alpha reductase

used for prostate cancer

Question 22

HRE function

Answer 22

Hormone response elements

gonadotropin feedback 
spermatogenesis
sexual differentiation 
anabolic effects 
libido

Question 23

DHT function

Answer 23

prostate development
external virilization
sexual maturation at puberty
baldness

Question 24

The administration of clomiphene (a SERM) would most likely lead to….?

Answer 24

Not done here