Male Reproductive Physiology system .ppt

Male Reproductive Physiology system .ppt

1. Testis
Hormonal Regulation of Spermatogenesis
Intratesticular Testosterone levels are 100 x greater than serum levels
Testosterone will initiate & qualitatively maintain spermatogenesis in humans
Genetic Basis of Spermatogenesis
AZF(azoospermia factor) region on long arm of Y c’some implicated in deletions
resulting in azoospermia
Paternal centromere: appears to organize embryonic mitotic activity; viable
embryo cannot be produced w/out this contribution

2. Epididymis
Function
Sperm transport: 2 -12 days; transport time influenced by daily
testicular sperm production; 2 days in men w/ high sperm counts vs
6 days in men w/ low sperm counts; recent emission reduces transit
time thru Cauda by 68%; principal mechanism for moving
spermatozoa thru epididymis is probably due to spontaneous
rhythmic contractions of cells surrounding epididymal tract
Sperm storage: 50% of total # of epididymal spermatozoa are
stored in Cauda (capable of undergoing motility & have capacity to
fertilize); fate of unejaculated spermatozoa is unknown

3. Epididymis
Function
Sperm motility maturation: increase motility observed during transit
Efferent ducts: 0%
Caput: 3%
Proximal Corpus: 12%
Distal Corpus: 30%
Cauda: 60%

4. Epididymis
Function
Sperm fertility maturation:
Testicular spermatozoa are incapable
of fertilizing eggs (unless injected)
Maturation is achieved at level of distal
Corpusor proximal Cauda
Biochemical changes:
Increased capacity for glycolysis
Changes in intracellular pH & calcium
content
Modification of adenylate cyclase
activity
Alterations in cellular phospholipid &
phospholipid-like fatty acid content

5. Ductus Vas Deferens
Spermatozoal transport
Ductus exhibits spontaneous motility, has capacity to respond when
stretched & contents of ductus can be propelled into urethra by strong
peristaltic contractions elicited by stimulation of hypogastric nerve or
adrenergic neurotransmitters
Immediately before emission, rapid & effective transport of spermatozoa
from distal epididymis & proximal vas deferens occurs (apparently related to
sympathetic stimulation)
This efficient transport of spermatozoa has revealed that the ductus
deferens has the greatest muscle-lumen ratio (10:1) of any hollow viscus in
the human body
Epididymal spermatozoal reserves: 182 million (26% caput, 23% corpus,
52% cauda); transit times in days (0.7 caput, 0.7 corpus, 1.8 cauda)
Ductus spermatozoal reserves: 130 million; storage site for spermatozoa

6. Ductus Vas Deferens
Spermatozoal transport
“During the sexual rest, epididymal contents were transported distally
through the vas deferens into the urethra in small amounts and at irregular
intervals”
Urethral disposal is a mechanism for ridding the epididymis of excess
spermatozoa
After sexual stimulation and/or ejaculation: contents of ductus can be
propelled towards proximal ductus & cauda epididymis because distal
portion had increased contractility compared to proximal portion of ductus
Refluxing was noted to reverse w/ sexual rest

7. Ductus Vas Deferens
Absorption & Secretion
Suggested that ductus deferens may have absorptive & secretory functions
Principal cells have characteristics typical of cells that are capable of
synthesizing & secreting glycoproteins
Stereocilia, apical blebbing, primary & secondary lysosomes of Principal
cells are characteristic of cells involved in absorptive functions
Rat models have shown that terminal region of ductus possesses the ability
to phagocytose & absorb spermatozoa; unknown if significant portion of
human ductus deferens possesses sufficient spermiophagy
Structure & function of ductus deferens probably depends on androgen
stimulation
Human ductus deferens converts Testosterone to DHT
Castration causes atrophy of ductus deferens; Testosterone treatment causes
restoration of ductus deferens
Castration and/or Testosterone treatment alters adrenergic contractions of ductus