Early Embryogenesis and Maternal Recognition of Pregnancy

Question 1

what has to happen to 1 parents’ copy of genes in parental imprinting and how is it determined?

Answer 1

have to inactivate 1 parents’ copy, based on function

Question 2

what happens when you remove a female pronucleus and add a male pronucleus?

Answer 2

you get a stunted embryo, but a normal placenta

Question 3

what happens when you remove a male pronucleus and add a female pronucleus?

Answer 3

you get a normal embryo but a stunted placenta

Question 4

what happens when you swap pronuclei but keep one male and one female?

Answer 4

normal embryo and normal placenta

Question 5

what is each cell in a 2-celled embryo and onward called?

Answer 5

a blastomere

Question 6

what are the blastomeres in a 2-celled embryo defined as in terms of potential? what does this mean?

Answer 6

totipotent; have the potential to develop into any type of cell in the body; true embryonic stem cells

Question 7

how many blastomeres are in a morula?

Answer 7

32-100

Question 8

what is the thing called before syngamy?

Answer 8

ootid

Question 9

what must a morula undergo in order to become a blastocyst?

Answer 9

blastulation

Question 10

what is the inner cell mass in a blastocyst in terms of cell potential?

Answer 10

pluripotent: have potential to become several different types of cells, but not all cell types

Question 11

what type of junctions does the inner cell mass have and why?

Answer 11

gap junctions to maintain communication between cells of the inner cell mass

Question 12

what will the inner cell mass become?

Answer 12

the embryo proper, the fetus, and some placental tissue

Question 13

describe the trophectoderm of a blastocyst, and give types of junctions and function

Answer 13

makes up lots of the placenta, has tight junctions which open to allow fluid inside the embryo

Question 14

what is hatching?

Answer 14

when the embryo squeezes through the hole in the zona pellucida

Question 15

what is the trophectoderm also called?

Answer 15

trophoblast

Question 16

what is the fluid cavity of a blastocyst also called?

Answer 16

blastocoel

Question 17

what is the inner cell mass also called?

Answer 17

embryoblast

Question 18

list the 7 stages of a fertilized oocyte from earliest to latest

Answer 18

1. ootid undergoes syngamy to become a
2. zygote which has its first cell division and becomes a
3. 2-celled embryo
4. morula which undergoes blastulation to become a
5. early blastocyst
6. hatching blastocyst
7. hatched blastocyst

Question 19

at what stage(s) of development does the oocyte enter the uterus?

Answer 19

morula/early blastocyst stage

Question 20

when does hatching occur in bovines?

Answer 20

9-11 days post fertilization

Question 21

when does hatching occur in equines and ewes?

Answer 21

7-8 days post fertilization

Question 22

when does hatching occur in porcines?

Answer 22

6 days post fertilization

Question 23

what occurs in equines before hatching? on what days?

Answer 23

capsul formation; 6-7 days post fertilization

Question 24

where does the capsul form in equines before hatching? what seems to be the function

Answer 24

between the embryo and the zona pellucida; seems to be important for maternal recognition

Question 25

what other species also forms a capsule before hatching?

Answer 25

rabbits

Question 26

list the 3 stages of conceptus growth in cows, pigs, and sheep

Answer 26

1. spherical 2. tubular 3. filamentous

Question 27

what elongates in the conceptus as it grows in cows, pigs, and sheep?

Answer 27

trophoblast

Question 28

when the blastocyst/conceptus elongates in ruminants (bovine and ovine), where is it located?

Answer 28

embryo fixes on same side as ovulation, closest to the CL

Question 29

describe pig intrauterine/transuterine migration

Answer 29

embryos from the L and R horns become mixed and fixed all along the tract, multiple embryos from multiple ovulations

Question 30

is transuterine migration often seen in cows or ewes?

Answer 30

no, it is rare in these animals

Question 31

when does transuterine migration begin in mares?

Answer 31

day 10 post fertilization

Question 32

when does fixation occur in the mare?

Answer 32

day 15-16

Question 33

where does fixation occur in the mare?

Answer 33

can occur in either horn

Question 34

why does fixation occur on day 15-16 in the mare?

Answer 34

embryo gets too big to move around after that

Question 35

list the 2 very general, no species variation steps in maternal recognition of pregnancy

Answer 35

1. conceptus will secrete either proteins or steroids | 2. secretions cause a maternal response to ercognize pregnancy

Question 36

list the 3 steps of maternal recognition of pregnancy in bovines and ovines (ruminants)

Answer 36

1. conceptus secretes interferons 2. interferons inhibit oxytocin receptor synthesis 3. this inhibits PGF2a synthesis

Question 37

what interferons are secreted by ruminant conceptus

Answer 37

Tau oIFN-t (ovine interferon tau) bIFN-t (bovine interferon tau)

Question 38

what is the mechanism of ruminant maternal recognition of pregnancy?

Answer 38

antiluteolytic

Question 39

what are the critical days for bovine maternal recognition of pregnancy?

Answer 39

days 16-17

Question 40

what are the critical days for ovine maternal recognition of pregnancy?

Answer 40

days 12-13

Question 41

list the 2 steps of porcine maternal recognition of pregnancy

Answer 41

1. conceptus secretes estradiol | 2. estradiol redirects PGF2a into the lumen, where it is degraded and never makes it to regress the CL

Question 42

what does procine maternal recognition of pregnancy require? what does this mean about transmigration of embryos?

Answer 42

2 embryos per horn; why transmigration of embryos is such a necessary process

Question 43

what is the mechanism of procine maternal recognition of pregnancy?

Answer 43

antiluteolytic

Question 44

what are the critical days for porcine maternal recognition of pregnancy?

Answer 44

days 11-12

Question 45

how is maternal recognition of pregnancy accomplished in the mare?

Answer 45

we don't know exactly

Question 46

what is the mechanism of maternal recognition of pregnancy in a mare?

Answer 46

antiluteolytic

Question 47

what do we know about maternal recognition of pregnancy in a mare?

Answer 47

we know it has to do with transmigration of the embryo but aren't sure specifically what about it

Question 48

what are the critical days for maternal recognition of pregnancy in a mare?

Answer 48

days 10-14

Question 49

list the 2 steps of maternal recognition of pregnancy in humans

Answer 49

1. conceptus secretes hCG | 2. hCG tells CL not to self-destruct

Question 50

what is the mechanism of maternal recognition of pregnancy in humans?

Answer 50

luteotrophic

Question 51

what are the critical days for maternal recognition of pregnancy in humans?

Answer 51

days 8-12

Question 52

does the CL of dogs and cats regress if the animal is not pregnant?

Answer 52

no, lack of an embryo causes no uterine effect

Question 53

what happens in dogs and cats even if the animal is not pregnant? how long does the CL last?

Answer 53

pseudopregnancy; CL will last similar length as in pregnancy