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Flashcards in male repro physio Deck (12):

SRY gene

development of testes --> spermatagonia, sertoli cells (produce AMH), leydig cells (produce testosterone)


retention of wollfian ducts

results from testosterone (made from leydig cells)

regression of mullerian duct - results from AMH production by sertoli cells



testosterone stimulates the urethral epihtleium and primorordia along with GHT to formation of male-type external genitalia (prostate gland and penis)


what results in conversion to dihydrotestosterone in scrotum

5alpha reductase


testosterone production

Produced by Leydig cells of testes

Production begins in fetus by 8 weeks gestation
- Leydig cell production of testosterone is initially stimulated by hCG (human chorionic gonadotropic) which is structurally similar to pituitary LH (luteinizing hormone) before LH takes over

After production, androgens diffuse to target cells and bind to androgen receptors
Androgen receptor complex (AR) is a nuclear receptor which directs protein synthesis
-- Binds T both DHT (unclear mechanism by which AR receptor differentiates in different cell types)


DHT production

Dihydrotestosterone (DHT) Production:

DHT is formed from testosterone by 5α-reductase-2 in peripheral tissues (urogenital tract, skin, hair folicles, liver); binds AR

T --> DHT (via 5α-reductase-2): Important role puberty changes
- Growth and activity of prostate gland
- Growth of penis
- Darkening and folding of scrotum
- Growth of pubic, axillary, facial, and body hair
- Increased muscle mass

5α-reductase-1: primarily expressed in skin, contributes to sebaceous gland activity and acne associated with puberty

Deficiency of 5α-reductase-2 results in ambiguous external genitalia

5α-reductase-2 inhibitors have benefited treatment of prostatic hypertrophy and prostatic cancer


actions of androgens

1. Fetal differentiation of male internal (T) and external genitalia (DHT)
2. Growth, development of secondary sexual characteristics at puberty
3. Maintenance of reproductive tract & production of semen
4. Initiation and maintenance of spermatogenesis

1. Stimulation of erythropoietin synthesis
2. Stimulation of sebaceous gland secretion
3. Control of protein anabolic effects (nitrogen retention)
4. Stimulation of linear body growth, bone growth and closure of the epiphyses
5. Promotion of ABP synthesis
6. Maintenance of secretions of sex glands
7. Regulation of behavioral effects, including libido


leydig vs. sertoli cells

leydig cells = produce testosteorne (stimulated by LH)
- Note: hCG is structurally similar to LH and can act to stimulate Leydig cells
- T, DHT, and E: Negative feedback mainly on LH production

sertoli cells = nursing cells that help mature sperm (stimulated by FSH)
- also results in ABP
- spermatogenesis
- production of inhibin (neg. feedback on FSH)


sertoli cells

Supportive Function:
- Maintaining blood-testis barrier
- Phagocytosis
- Transfer of nutrients to sperm
- Receptors for hormones & paracrines

Exocrine Function:
- Fluid produced for sperm mobilization
- Production of ABP (Androgen binding protein)
- Spermination: release of sperm from seminiferous tubule

Endocrine Function:
-Expression of testosterone, ABP and FSH receptors
- Production of AMH (Antimϋllerian hormone)
- CYP19 Aromatase: testosterone --> estradiol-17β (local)
-Production of inhibin to regulate FSH levels


35 y/o male with infertility, has sparse facial hair and decreased sexual development. Testosterone is low, LH and FSH are elevated. Semen is low. Sperm concentration is low.

karyotype shows 47XXY = klinefelters

most common sx:
- infertility
- gynecomastia: swelling of the breast tissue in boys or men


look over the BSC questions

do it now.


primary hypogonadism

high gonadotropins (high FSH/LH )
androgen production reduced