REPRODUCTION Flashcards
external male genitalia
Penis
scrotum
internal male genitalia
seminal vesicle
ejaculatory duct
epididymis
vas deferens
prostate gland
bulbourethral gland
male gonads
§ Primary reproductive organs to produce gametes (sperms) and secrete sex hormones (testosterones)
§ Testis:
□ pair, located in scrotum, skin-covered sac suspended
□ Produce sperm, testosterone
male testes descent
1) Testosterone release from fetal testes
2) Shorten gubernaculum (cord of muscle)
3) Decent completed usually by 7th mnth of gestation
a) Testes descent (rear of abdominal cavity)
4) descent on 2 sides of scrotum
why testes needs to descent
• Spermatogenesis
• Temperature sensitive
• Cannot occur at normal body temp
• 35*C (<2)
(Temperature to produce viable sperms)
undescended testes
Undescended testes into adulthood (cryptorchidism)
• Rare
• Surgical intervention
temperature in scrotum
35
when does spermatogenesis occurs?
PUBERTY
• Enlargement of testes and development of 2nd characteristics
• Hormonal changes “raging hormones”
spermatogenesis HORMONES, cells and duration
inhibin (from sertoli cell)
- nutrients for sperm prod, support
Testosterone (Leydig cell)
germ cells at various stage of differentiation, each take 64 days, does not occur synchrously
hormones in puberty (male)
Testosterone (Leydig cell)
GnRH (Gonadotropic-releasing hormone) (hypo)
LH (luteinizing hormone) – (ant pitui)
FSH (follicle stimulating hormone) – (ant pitui)
Inhibin (from sertoli cell)
- nutrients for sperm prod
why is GnRH released in pulsatile ~1-3hrs
hypothalamus release GnRH
for proper functioning of testes, regulate secretion of FSH, LH (also in pulsatile)
if constant GnRH exposure to gonadotrophs, desensitised GnRH receptors (overall decr LH, FSH)
control of testicular function byNEGATIVE FEEDBACK:
1) testosterone incr
2) act on hypothalamus, anterior pituitary
3) decr GnRH release by acting on hypothalamus
4) indirectly decr LH, FSH release by (ant, pitui)
2) act on sertoli cell, incr inhibin production
3) inhibit FSH secretion
effects of testosterone
• Internal male genitals (differentiation)
• Pubertal growth spurt
• Penis (growth)
• Deepening of voice
• Spermatogenesis
• Libido
• Muscle mass
ANABOLIC STEROIDS EFFECT
- incr in testosteron
- inhibin produced (sertoli cell) to inhibit ant pituitary
- testes do not receive stimulus from ant. pitui (GnRH –> LH, FSH –> testes –> testosterone)
- testosterone secretion, sperm production decr = SHRINK
biosynthesis of DHT
5a-reductase]
Cholesterol precursor —> Dihydrotestosterone [5a-reductase]
+ Estradiol [Aromatase]
effects of DHT
® External male genitalia (differentiation)
® Sebaceous glands
® Prostate (growth)
® Male hair pattern BALDNESS