Lecture 5: Gamete Transport and Fertilization Flashcards
What is the main mechanism for transport of the egg in uterine tube?
Contractions of tubal smooth muscle
Which type of transport requires progesterone?
A. Slow transport in ampulla
B. Rapid transport through isthmus
C. Medium transport in ampulla
B. Rapid transport through isthmus
When does the egg arrive in the uterus?
3-4 days after departure
What mechanisms propel immotile sperm through male reproductive tract?
Passive transport via testicular fluid, muscle contraction, cilia from seminiferous tubules
What is the path of sperm to the point that it reaches the epididymis?
Rete testis, efferent ductules, epididymis
Where does sperm maturation occur and how long does it require?
Epididymis, 12 days
Which of the following fluid secretions provide nutrition and energy supply for sperm?
A. Prostaglandins
B. Fructose
C. Citric acid
D. Phosphatase
B. Fructose
The acidic pH of which of the following structures is of most concern regarding the passage of sperm?
A. Upper vagina
B. Cervix
C. Upper uterine tube
D. Isthmus
A. Upper vagina
What is the optimal pH for sperm motility?
6.0-6.5
Initial rapid transport of sperm
Spermatozoa reach uterine tubes within 5-20 minutes of ejaculation; relies on muscular movement of female tract; sperm not as capable of fertilization
Slow transport of sperm
Sperm may not reach oviducts for 2-4 days; involves swimming through cervical mucous and storage in cervical crypts; sperm more capable of fertilization
Where does fertilization typically occur?
Ampulla
Capacitation
Required for sperm to undergo acrosomal reaction and fertilize egg; involves removal of cholesterol and glycoproteins
Where does capacitation occur?
Isthmus of uterine tube
What enzyme found in the acrosome is responsible for penetration of the corona radiata?
Hyaluronidase
What protein stimulates the acrosomal reaction in mammals?
ZP3
Where is acrosin/zona lysin initially found and what is its purpose?
Found in acrosome, digests small hole through ZP and assists in penetration of sperm through ZP
Fast block to polyspermy
Rapid depolarization of egg plasmalemma that temporarily prevents polyspermy and allows time for slow block to be established
Slow block to polyspermy
Release of polysaccharides from the cortical granules located just under the plasmalemma of the egg, causing a swelling that increases perivitelline space
Phospholipase C zeta
Produced by sperm and facilitates Ca2+ release in egg, making it metabolically active
Pronucleus
Nuclear material of the head of spermatozoan or of the oocyte after the oocyte has been penetrated by the spermatozoan
Zygote
Denotes single-celled stage at which the male and female pronuclei have fused together and share a common membrane, establishing the diploid chromosome number
