Lecture 6 - Male Reproductive Tract II

Question 1

Testicular Changes in puberty?

Answer 1

marked increase in proliferation of spermatagonia, cords develop lumen and become seminiferous tubules, sperm production

Question 2

Spermatogenesis - mitotic division?

Answer 2

reactivated germ cells (spermatogonial stem cells) mitose, one undifferentiated to maintain population, one into spermatagonia which continues to divide, move from sertoli to seminiferous tubule adluminal compartment -> primary spermatocytes

Question 3

Spermatogenesis - meiotic division?

Answer 3

primary spermatocyte undergoes meiosis I to become secondary (chr 46 -> 23), meiosis II into 4 spermatids (23)

Question 4

Spermatogensis - cytodifferentiation?

Answer 4

androgen dependent - spermatids shed residual cytoplasm as residual body, move to lumen

Question 5

LH pathway?

Answer 5

released from ant. pituitary following GnRH stimulation from hypothalamus, stimulates testosterone release from Leydig cells, DHT most potent sort for secondary sexual characteristics (short and long negative feedback loop)

Question 6

FSH pathway?

Answer 6

released from anterior pituitary following GnRH stimulation from hypothalamus, simulate sertoli cells to release androgen binding protein, transports testosterones around body (inhibin release negatively feeds back short loop)

Question 7

Secondary sexual characteristics?

Answer 7

aggresiveness, libido, hair growth, baldness

Question 8

Continuous sperm production?

Answer 8

segmental progression of spermatogensis along tubule

Question 9

Epididymis functions?

Answer 9

concentrate semen 100x fold with spern, stereocilia for reabsorption, sperm gain ability for motility and fertilisation

Question 10

Vas deferens?

Answer 10

major storage site of sperm, three muscular layers: inner and outer longitudinal and middle circular, simple lumen at epididymal end then enlarged w crypts for greater sperm storage at the ampulla (prostate end)

Question 11

Seminal vesicle funtion?

Answer 11

secrete alkaline fluid via excretory duct, with Semenogelin that causes semen clotting post ejaculation (I and II types, also with fibronectin)

Question 12

Prostate gland?

Answer 12

surrounds prostatic urethra, secretes acidic fuid containing PSA (used in out of NZ cancer screening)

Question 13

Prostate zones?

Answer 13

central (not prone to carcinoma), peripheral (prone to carcinoma), transition (site of benign hyperplasia), anterior (muscle no glands)

Question 14

Erection?

Answer 14

parasymp. release of Ach, inducing NO release by corpora endothelial cells, inducing cGMP production causing vasodilation, corpora relax and fill with blood, venous outflow reduced leading to erection

Question 15

Viagra action?

Answer 15

blocks type V phosphodiesterase, reducing cGMP metabolism, causing vasodilation - useless for parasympathetic nerve damage as no NO causing cGMP production

Question 16

Semen components?

Answer 16

prostatic fluid (30%), sperm (10%, seminal vesicle fluid (60%) - 2-5ml volume with 20mil/mL