Reproductive Endo in Males

Question 1

Absence of Testosterone –>

Absence of AMH –>

Answer 1

Absence of Testosterone –>
Wolffian ducts involute

Absence of AMH –>
mullerian ducts spontaneously differentiates

Question 2

Development of female ducts and external genitalia is independent of _____

Answer 2

gonadal hormones

*if no gonads, female formation results

Question 3

Sertoli cells

Answer 3

1. Testis formation
2. Nurture sperm
   - germ cells –> spermatogonia (consumes cytoplasm of germ cells)
3. Forms tight junctions - blood testis barrier
   - or else autoimmune response to sperm
4. Convert androgens to estrogens (via aromatase)
5. Secrete inhibin, GF, aromatase, Androgen binding protein

*Respond to FSH thru GPCR (not LH like leydig)

Question 4

Leydig cells

Answer 4

1. required for spermatogenesis
2. Synthesis of testosterone (95%)
3. Synthesis of Steroidogenic acute regulatory protein (StAR) and sterol carrier protein (SCP)

• Respond to LH through a GPCR

Question 5

Are Leydig or sertoli cells necessary for testicular fxn?

Answer 5

both

Inhibins released from sertoli cells in response to FSH cells act locally as growth factors for Leydig cells

FSH (acting on sertoli cells) regulates proliferation and devel of leydig cells to provide adequate T for spermatogenesis

T from leydig cells synergizes with FSH to increase Androgen binding protein (ABP) production in sertoli cells to maintain high local T [ ]

Question 6

HPT Axis:

GnRH stimulates production of ___ + __ from pituitary. What do they act on?

Answer 6

LH –> acts on Leydig cells

FSH –> acts on Sertoli cells

Question 7

HCG in athletes

Answer 7

Looks like LH (stim fetal tetes to make T)

If they abuse T, then stop taking them, their T lvls would drop.

Stop Taking HCG:
Turns back on normal endogenous production.
- Restore physiologic Testosterone levels

Question 8

Inhibin

Answer 8

suppresses FSH production from pituitary gonadotrophs

Question 9

Testosterone inhibits release of ____ from ____.

Estrogen inhibits ____ from ____.

Answer 9

T: inhib GnRH from hypothal

E: inhibit LH + FSH from pituitary

Question 10

Sertoli cell only syndrome

Answer 10

all levels are normal, but you have no gametes

may have patches of gametes

Question 11

What would sperm count look like in indiv who abuse T?

Answer 11

Exogenous T would shut down fxn of testis and not make any sperm
- also see shrinkage

Question 12

Male pubertal growth is due to?

Answer 12

1. Increased GH
2. Increased T

Pubertal growth spurt

Question 13

Pre-pubertal males equal. . .

Answer 13

body mass,
skeletal mass
body fat

(then after: everything increases except for fat, males have 50% of female body fat)

Question 14

Androgenic effects

Answer 14

1. GRowth and devel of male repro tract
2. 2ndary sexual characteristics
3. Behavioral responses

Question 15

Anabolic effects in puberty

Answer 15

1. Growth of somatic tissue
2. linear body growth (long bones)
3. Nitrogen retention, protein synthesis
4. Muscle development

Question 16

GH/IGF-1 stimulates

Answer 16

1. gonadal function +
2. body growth

(IGF-1 stimulates GnRH secretion)
*look at HPT axis

Question 17

GH/IGF-1 and HPT axes

Answer 17

High GnRH -->
Increase LH and FSH --> 
Increase gonadal fxn -->
Increase T and E2 -->
Increase body growth + GH

High GnRH –> Increase GH –>
Increase IGF-1 –>
Increase body growth

(chart in handout)

Question 18

Prepuberty indiv abusing steroids

Answer 18

grows more rapidly but ends up as shorter statute

• promotes epiphyseal closure
• narrow growth window limiting long bone growth

Question 19

Consequences of steroid abuse

Answer 19

lots

1. infertility (decreased sperm prod)
2. Gynecomastia
3. Testicular atrophy
4. baldness + excessive body hair
5. Short stature
6. Tendon rupture
7. Increased LDL
   Decreased HDL (atherosclerosis)
8. High BP
9. Heart attack n stroke
   10 Liver cancer
10. Severe acne
11. kidney failure
12. Psychiatric disturbances