updated 3/24/99

Gamete Transport

Reading

• Chapter 12

Lecture:

Sperm transport in the Male

• fluid flow
  • seminiferous tubule
  • vas efferentia
• cilia
  • vas efferentia
• muscle contractions
  • epididymis
  • vas deferens
  • pelvic urethra
  • penile urethra

Sperm in the epididymis

• no protein synthetic ability
• addition or loss of plasma membrane proteins and lipids
• redistribution of proteins and lipids within sperm
• changes in lipid diffusion coefficients
• the above lead to:
  • acquisition of
    • fertilizing ability
    • motility

Decapacitation Factors

• protein, glycolipid and/or lipid
• stabilizes the plasma membrane to delay or prevent capacitation
• can be secreted from the epididymis and/or accessory glands

Site of Ejaculation	Semen Characteristics	Species
Vagina	Slight coagulation of ejaculate	human, rabbit
Vagina	semen with high sperm concentration	cattle, sheep
Uterus	voluminous, distention of cervix	horse
Cervix, uterus	voluminous, retention of penis during copulation	dog, pig
Uterus	vaginal plug	rodents

Sperm loss from the female tract

• retrograde flow
• phagocytosis by neutrophils

Evolutionary strategies for dealing with retrograde flow of semen

• coagulation of semen or a plug
• concentrated semen
• semen deposited in uterus

Phases of sperm transport

• rapid (15 - 30 min)
• sustained 6-12 hr)
• oviductal (at ovulation, 1-2 hr)

Evidence of sustained sperm transport

Ovulation and its relationship to sperm transport

• release of oocyte, cumulus cells and follicular fluid into oviduct
• components of ovulation or signal may trigger oviductal transport of sperm

Length of time sperm reside in different parts of the cow reproductive tract

• 6 - 12 in the uterus
• 18 - 24 hours in the oviduct (in the isthmus reservoir)
• 1 - 2 hours at the ampulla-isthmic junction of the oviduct

Barriers to sperm transport

• cervix
• uterus
• utero-tubal junction

Oocyte transport in the oviduct

• fluid flow towards infundibulum
  • UTJ is closed until day 3 - 5 post ovulation
  • secretion from epithelial cells in isthmus and ampulla
• ampulla
  • cilia beat toward isthmus
  • muscle contractions move toward isthmus
• isthmus
  • no muscle contractions
  • no cilia
• ampulla-isthmic junction
  • defacto site where oocyte ends up after ovulation so this is where fertilization occurs

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