Male Reproductive Physiology

Question 1

Scrotum

Answer 1

Skin and fascia around testes
3° cooler than body temperature
Smooth muscle (contracts and pulls testes close when cold, relaxes when warm)
Temperature is critical to sperm survival

Question 2

Testes

Answer 2

Produce testosterone 
Leydig cells 
Triggered by LH
Sperm production 
Contains ~800 feet of seminiferous tubules 
Each testis into 250-300 lobules 
Lobules contain 1-4 seminiferous tubules

Question 3

Spermatogenesis

Answer 3

64-74 days to maturation
~200 million a day
20% are rejects
Require proper temperature and pH for motility and numbers

Question 4

Anatomy of spermatozoan

Answer 4

Tail for motility
DNA head
Acrosome (digestive enzymes, break down egg wall)
Mitochondria (energy)

Question 5

Seminiferous tubules

Answer 5

Germ cells (sperm forming cells)
Sustentacular/serotoli cells (support cells)

Question 6

Microscopic anatomy

Answer 6

Serotoli cells =
Blood testis barrier
Assist sperm production (differentiation, phagocytizes defective sperm)
Secrete seminiferous fluid
AIDS leydig cells to secrete testosterone
Secrete inhibin (inhibits FSH)

Question 7

Epididymis

Answer 7

6m long (when uncoiled)
20 day journey
Site of sperm maturation

Question 8

Ductus or vas deferens

Answer 8

Stores and transports sperm

Stored for up to 2 months (then reabsorbed)

Question 9

Accessory glands

Answer 9

Secretions vital to sperm survival
Seminal vesicles
Prostate gland
Bulbourethral gland (cowpers gland)

Question 10

Seminal vesicles

Answer 10

~60% of semen volume 
Fructose to nourish sperm 
Alkali (neutralize vaginal acid) 
Substances for sperm motility 
Prostaglandins (vaginal contractions) 
Clotting factors (inertial)

Question 11

Prostate gland

Answer 11

Encircles urethra 
20-30 compound glands 
~25-30% of seminal fluid 
Alkali (neutralizes vaginal acid)
Prostaglandins (enhances sperm motility)
Enzymes that clot then liquefy semen

Question 12

Bulbourethral gland

Answer 12

Pea sized
Inferior to prostate
Produces mucous (neutralizes traces of acidic urine, lubricates urethra)

Question 13

Ejaculation

Answer 13

Vasodilation to penis 
Increased blood flow 
Erection (parasympathetic control)
Ejaculation (sympathetic control) 
Ejaculate = 4-7mL, semen, ~400 million sperm

Question 14

Male fertility problems

Answer 14

Blocked tubules
Decreased sperm count (usually hormonal)
Decreased sperm motility (hormonal)
Decreased semen secretion (needed for sperm viability and survival)

Question 15

Male vs. Female sperm

Answer 15

Male (Y) = lighter, faster, more fragile, die in ~24 hours, conceived if “deposit” close to ovulation (day 14)
Female (X) = heavier, slower swimmers, hardier, live 2-3 days, conceived if “deposit” is early in cycle (day 11-13)