Fertilization

Question 1

Which species deposit sperm into the anterior vagina?

Answer 1

Cow
Ewe
Doe
Bitch

Question 2

What are the post-capacitation events leading to fertilization?

Answer 2

• hyperactive motility
• binding to zona pellucida
• acrosomal reaction
• penetration of zona pellucida
• sperm-oocyte membrane fusion
• sperm engulfed
• decondensation of sperm nucleus
• formation of male pronucleus

Question 3

Describe the acrosome reaction

Answer 3

• enzymes are released
• penetration of sperm through zona pellucida
• sperm enter perivitelline space
• membranes fuse
• cortical reaction induced

Question 4

Describe the cortical reaction

Answer 4

• sperm head attaches to oocyte plasma membrane and initiate blockage of polyspermy
• ZP hardens and vitelline membrane changes

Question 5

Where does fertilization take place in the cow?

Answer 5

apulla-isthmus junction of the oviduct

Question 6

What is syngamy?

Answer 6

fusion of male and female pronuclei

Question 7

What are the barriers to fertilization?

Answer 7

• cumulus cells (surround ovulated oocyte)
• zona pellucida
• oocyte membrane

Question 8

What must occur before the embyro can attach to the uterus?

Answer 8

• develop within the zona pellucida
• subsequent hatch from ZP
• maternal recognition of pregnancy
• formation of extra-embryonic membranes

Question 9

What is totipotency?

Answer 9

the ability of a single blastomere to develop into a fully formed individual

Question 10

What is the most totipotent cell?

Answer 10

zygote

Question 11

Describe what occurs in development of a free martin

Answer 11

• AMH from bull block mullerian ducts, resulting in posterior vagina with no anterior vagina
• testosterone from bull causes clitoral enlargement and brain changes
• ovaries do not grow, but are chimeric (ovotestis)

Question 12

What happens if there is no maternal recognition of the embryo?

Answer 12

PGF2a is produced, lysis of the CL, and the animal goes back to estrus
- the bitch will not return to cycle

Question 13

Describe maternal recognition in ruminants

Answer 13

• interferon tau is produced by trophoblastic cells

- inhibits oxytocin receptor synthesis, therefore no PGF2a release

Question 14

Describe maternal recognition in the sow

Answer 14

• blastocyst produces estradiol
• re-routes PGF2a release into the uterine lumen where it is destroyed
• need at least 2 conceptus in each horn

Question 15

Describe maternal recognition in the mare

Answer 15

• PGE2 is produced by the embryo
• blastocyst trans-uterine migration
• reduced synthesis of PGF2a

Question 16

What is the functional unit of the placenta?

Answer 16

chorionic villi

Question 17

What are the layers in an epitheliochorial fetal/maternal relationship?

Answer 17

• endometrial endothelium
• endometrial interstitium
• endometrial epithelium
• chorionic epithelium
• chorionic interstitium
• chorionic endothelium

Question 18

What are the layers in an endotheliochorial fetal/maternal relationship?

Answer 18

• endometrial endothelium
• endometrial interstitium
• chorionic epithelium
• chorionic interstitium
• chorionic endothelium

Question 19

What are the laters in a hemochorial fetal/maternal relationship?

Answer 19

• chorionic epithelium
• chorionic interstitium
• chorionic endothelium
• direct contact with maternal blood pool

Question 20

Which species have epitheliochorial fetal/maternal relationship?

Answer 20

sow, mare, camelid, cow, ewe, doe

Question 21

Which species have endotheliochorial fetal/maternal relationship?

Answer 21

bitch and queen

Question 22

In a cotyledonary placenta, which is the maternal portion, and which is the fetal portion?

Answer 22

maternal - caruncles

fetal - cotyledons

Question 23

What is a placentome?

Answer 23

caruncle/cotyledon complex

Question 24

Which species have diffuse placenta?

Answer 24

mare, sow, camelid

Question 25

Which species have cotyledonary placenta?

Answer 25

cow, ewe, doe, deer

Question 26

Which species have zonary placenta?

Answer 26

bitch, queen, ferret

Question 27

What are the functions of the placenta?

Answer 27

- stimulate ovarian function (eCG) - stimulate mammary function (lactogen) - induction of parturition (convert P4 to estrogens) - assist in parturition (relaxin and estrogen) - maintain pregnancy (P4)

Question 28

What are endometrial cups?

Answer 28

- unique to the mare - produces equine chorionic gonadotropin - helps with luteinization of secondary CL