(5) Fetilization: Beginning a New Organism Part 3

Question 1

mammalian fertilization

Answer 1

a. internal/intercourse
b. obstacle: gametes must reach each other within female reproductive tract at the right time
c. human fertilization occurs in the ampulla of oviduct

Question 2

translocation of the egg

Answer 2

a. ovulated egg is surrounded by zona pellucida (extracellular matrix) and cumulus (follicle cells)
b. fimbriae of oviduct interact with cumulus and sweep egg into oviduct
c. ciliary beating and muscle contractions move egg to ampulla
d. sperm motility; flagellar movement (to cross cervical mucus layer and enter uterus)
e. uterine muscle contractions (to move through uterus and into oviduct)
f. rheotaxis (to move toward egg; in response to directional cues)

Question 3

sperm “trains”

Answer 3

a. occurs in mammalian species where female is promiscuous (like mice)
b. sperm from single make form associations so that combined flagellar movement increases likelihood that that male’s sperm gets into egg

Question 4

sperm capacitation

Answer 4

1. newly ejaculated mammalian sperm are not capable of fertilizing the egg
2. maturation (capacitation) occurs as sperm move through female reproductive tract, in response to environmental factors
3. sperm gain the capacity to (a. move toward the egg, b. undergo acrosomal rxn, c. fuse with egg cell membrane)
   the “fastest” sperm is usually not the winner; might get stuck in oviduct; may take as long as 6 days for mature sperm to reach egg