Fertilization

Question 1

which female animals have semen depositing in the vagina?

Answer 1

ruminants, primates, rodents, cats

Question 2

which female animals have semen depositing in the cervix?

Answer 2

pigs, equids

Question 3

which female animals have semen depositing in the uterus?

Answer 3

dogs

Question 4

the __ is a major barrier to sperm transport (except pigs and dogs)

Answer 4

cervix

Question 5

cervical sperm transport has a 1. __ phase characterized by injection to uterus by ejaculatory force and a 2. __ phase where the sperm swim upgrade through channels in cervical crypts to avoid retrograde mucous flow

Answer 5

rapid, slow

Question 6

once in the uterus, sperm travel __ towards the __and accumulate there binding to epithelial cells until released into the __

Answer 6

anterograde, UTJ, oviduct

Question 7

define sperm capacitation and where it takes place

Answer 7

sperm capacitation is the physiologic changes that sperm undergo in the female tract to gain the capacity to undergo the acrosome reaction and usually takes place in the uterus or uterine tube of the female tract

Question 8

Sperm undergo capacitation to prepare for __ and undergo the acrosome reaction once bound to the __ of the oocyte

Answer 8

fertilization, zona pellucida

Question 9

capacitation of ejaculated sperm involves __ being added to sperm and blocking calcium transport, then in the capacitated sperm __ is removed and sperm is competent to bring calcium inside

Answer 9

caltrin

Question 10

define the acrosome reaction.

Answer 10

release and exposure of acrosomal contents

Question 11

steps of the acrosome reaction

Answer 11

1. sperm binds to zona pellucida via ligand receptor interaction (ZP3)
2. receptor on sperm triggers calcium influx
3. intracellular calcium rises causing membrane fusion
   - outer acrosomal and sperm cell membrane fuse
   - resulting pores permit escape of soluble acrosomal contents
   - exposure of inner acrosomal membrane which binds to ZP2

Question 12

sperm penetration of the zona pellucida depends on __ and __

Answer 12

acrosin- digested pathway and hyperactivated motility (helps get the sperm through the zona)

Question 13

briefly describe sperm - egg binding

Answer 13

1. entire sperm enters perivitelline space and motility diminishes
2. sperm binds to oocyte cell membrane
3. sperm ligand binds to oocyte surface receptor triggering depolarization and cortical reaction
4. the cortical reaction (exocytosis) releases proteases that alter the zona structure making it resistant to acrosin digestion (blocks polyspermy)

Question 14

when the sperm head first enters the ooplasm, it immediately__ and protamines are replaced by __ resulting in the haploid genome becoming organized into chromosomes

Answer 14

swells, histones

Question 15

the male pronucleus is the __and is surrounded by a pronuclear envelope and __ as it moves towards the center of the ovum ready for __ of mitosis

Answer 15

enlarging sperm head, microtubules, metaphase

Question 16

After kicking out the second polar body, the remaining haploid genome forms the ___ and moves to the center of the ovum where it is usually __ than the male pronucleus

Answer 16

female pronucleus, smaller

Question 17

Syngamy

Answer 17

when the 2 pronuclei reach the center, the pronuclear envelopes disappear and the two genomes become one. The chromosomes with duplicated chromatids line up on the metaphase plate for the first mitosis

Question 18

the morula undergoes __ between 8-16 cells by forming tight junctions with cell adhesion molecules between adjacent cells so that cell boundaries become difficult to see

Answer 18

compaction

Question 19

after the morula, a __ forms and the ICM and __ will continue to multiply while blastocoel fluid accumulates

Answer 19

blastocyst, trophoblast

Question 20

a blastocoel fluid accumulates in the blastocyst the __ streches and thins until it ruptures and __

Answer 20

zona pellucida, escapes