Lecture 5: Gamete Transport and Fertilization

Question 1

What is the main mechanism for transport of the egg in uterine tube?

Answer 1

Contractions of tubal smooth muscle

Question 2

Which type of transport requires progesterone?

A. Slow transport in ampulla
B. Rapid transport through isthmus
C. Medium transport in ampulla

Answer 2

B. Rapid transport through isthmus

Question 3

When does the egg arrive in the uterus?

Answer 3

3-4 days after departure

Question 4

What mechanisms propel immotile sperm through male reproductive tract?

Answer 4

Passive transport via testicular fluid, muscle contraction, cilia from seminiferous tubules

Question 5

What is the path of sperm to the point that it reaches the epididymis?

Answer 5

Rete testis, efferent ductules, epididymis

Question 6

Where does sperm maturation occur and how long does it require?

Answer 6

Epididymis, 12 days

Question 7

Which of the following fluid secretions provide nutrition and energy supply for sperm?

A. Prostaglandins
B. Fructose
C. Citric acid
D. Phosphatase

Answer 7

B. Fructose

Question 8

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

Answer 8

A. Upper vagina

Question 9

What is the optimal pH for sperm motility?

Answer 9

6.0-6.5

Question 10

Initial rapid transport of sperm

Answer 10

Spermatozoa reach uterine tubes within 5-20 minutes of ejaculation; relies on muscular movement of female tract; sperm not as capable of fertilization

Question 11

Slow transport of sperm

Answer 11

Sperm may not reach oviducts for 2-4 days; involves swimming through cervical mucous and storage in cervical crypts; sperm more capable of fertilization

Question 12

Where does fertilization typically occur?

Answer 12

Ampulla

Question 13

Capacitation

Answer 13

Required for sperm to undergo acrosomal reaction and fertilize egg; involves removal of cholesterol and glycoproteins

Question 14

Where does capacitation occur?

Answer 14

Isthmus of uterine tube

Question 15

What enzyme found in the acrosome is responsible for penetration of the corona radiata?

Answer 15

Hyaluronidase

Question 16

What protein stimulates the acrosomal reaction in mammals?

Answer 16

ZP3

Question 17

Where is acrosin/zona lysin initially found and what is its purpose?

Answer 17

Found in acrosome, digests small hole through ZP and assists in penetration of sperm through ZP

Question 18

Fast block to polyspermy

Answer 18

Rapid depolarization of egg plasmalemma that temporarily prevents polyspermy and allows time for slow block to be established

Question 19

Slow block to polyspermy

Answer 19

Release of polysaccharides from the cortical granules located just under the plasmalemma of the egg, causing a swelling that increases perivitelline space

Question 20

Phospholipase C zeta

Answer 20

Produced by sperm and facilitates Ca2+ release in egg, making it metabolically active

Question 21

Pronucleus

Answer 21

Nuclear material of the head of spermatozoan or of the oocyte after the oocyte has been penetrated by the spermatozoan

Question 22

Zygote

Answer 22

Denotes single-celled stage at which the male and female pronuclei have fused together and share a common membrane, establishing the diploid chromosome number