Fertilization, Maternal Recognition of Pregnancy and Placentation Flashcards Preview

Theriogenology > Fertilization, Maternal Recognition of Pregnancy and Placentation > Flashcards

Flashcards in Fertilization, Maternal Recognition of Pregnancy and Placentation Deck (58):
1

What needs to occur for fertilization?

Sperm needs to encounter oocyte

2

What is the general range of sperm viability?

Hours to days

3

Roughly how much sperm is lost via retrograde flow?

~50%

4

Where do the non-motile sperm get removed after breeding?

The cervix

5

Where is capacitation initiated?

The uterus.

6

Where is capacitation completed?

The oviduct.

7

What reaction must take place in order for fertilization to occur?

The acrosome reaction.

8

In what 3 species is the semen deposited in the uterus?

Pig
Alpaca
Horse

9

In what 5 species is semen deposited in the vagina?

Cows
Goats
Sheep
Dogs
Cats

10

Where do sperm mature?

Through the epididymus

11

Where is maximal sperm fertility achieved?

Only after residing in the female tract for a period of time

12

What are the changes that occur to sperm for final maturation?

Capacitation

13

What is the rapid phase of sperm transport?

Muscle contractions help the sperm arrive at the oviduct in minutes where they await the oocyte.

14

What is the sustained phase of sperm transport?

Sperm delivered continually from reservoirs.

NOTE: This is critical for animals the ovulate several oocytes.

15

What 2 areas are considered "reservoirs" for sperm?

Cervix
Uterotubual junction

16

What is the site of fertilization?

The Ampullary-isthmic junction

17

What is capacitation?

Stripping of the seminal plasma proteins by uterine factors.

18

What is the result of capacitation?

Hyper-activated sperm with unmasked ZP (zona pellucida) binding sites

19

What are the 3 layers of cells that act as a barrier to fertilization?

Cumulus cells
Zona Pellucida
Oolemma (oocyte membrane)

20

What is the function of the zona pellucida?

Prevents polyspermy

21

What initiates the acrosome reaction?

Binding of the sperm to the zona pellucida.

22

How is polyspermy prevented?

Once sperm binds to the oolemma, the zona pellucida hardens to prevent other sperm from binding.

23

What is syngamy?

Fusion of male and female pronuclei to form a zygote.

24

How many cells are in a zygote?

One

25

How many cells are in an embryo?

Many

26

Before the embryo can attache to the uterus, what 4 steps must first occur?

Develop within ZP
Hatch from ZP
Maternal recognition of pregnancy
Formation of extra-embryonic membranes

27

What is the site of fertilization in the cow?

The ampullaristhmic junction.

28

What is totipotency?

The ability of a single blastomere to develop into a fully formed individual animal.

29

Up to what stage is each blastomere totipotent?

8-16 cell stage

30

How many cells are in a morula?

16+ cells

31

What is the first fetal membrane you see at birth?

Amnion

32

Why do you not see the chorion first at birth?

Because it is attached to the dam.

33

What is the term if you see the chorion first at birth?

Red bag

NOTE: This is BAD, the chorion has been decomposing.

34

What are the 2 main goals of maternal recognition of pregnancy?

Preservation of the primary CL
Maintain high levels of progesterone

35

What must maternal recognition of pregnancy occur before?

Before luteolysis

36

What is the mechanism of maternal recognition of pregnancy in the cow?

Interferon-tau from trophoblast cells inhibits oxytocin receptor synthesis so no PGF2a is released.

37

What is the mechanism of maternal recognition of pregnancy in the sow?

The blastocyst produces estradiol which re-routes PGF2a where it is destroyed.

38

What is so different about equine maternal recognition of pregnancy?

The embryo needs to migrate everywhere to signal pregnancy.

39

What is different about maternal recognition of pregnancy in cats and dogs vs our large animal species?

The CL has a similar lifespan in bot pregnant and non-pregnant animals.

40

What membrane is the origin of the placenta?

The chorioallantois.

41

What type of placenta does a horse have?

Diffuse

NOTE: Sow also has diffuse

42

What type of placenta does a ruminant have?

Cotyledonary

43

What type of placenta does a primate have?

Discoid

44

What type of placenta does a dog or cat have?

Zonary

45

What is the point of attachment of the placenta to the dam?

Chorionic villi

46

How many layers of tissue exist between the maternal and fetal blood in an epitheliochorial placenta?

6 layers total; 3 maternal and 3 fetal

NOTE: Embryo ALWAYS has 3 layers.

47

How many layers of tissue exist between the maternal and fetal blood in an endotheliochorial placenta?

5 layers total; 2 maternal and 3 fetal

NOTE: Embryo ALWAYS has 3 layers.

48

How many layers of tissue exist between the maternal and fetal blood in a hemochorial placenta?

4 layers total; 1 maternal and 3 fetal

NOTE: Embryo ALWAYS has 3 layers.

49

What type of placenta does a sow have?

Diffuse

50

What 6 species have an epitheliochorial placenta?

Pig
Horse
Camelid
Cow
Sheep
Doe

51

What 2 species have an endotheliochorial placenta?

Dog
Cat

52

What 2 species have a hemochorial placenta?

Primates
Rodents

53

What is an additional mechanism of maternal recognition of pregnancy that we find in the horse?

Endometrial cups

54

What is produced by the endometrial cups?

Equine chorionic gonadotropin (eCG)

55

How does the placental induce parturition?

Convets P4s to estrogen

56

How does the placenta assist parturition?

Secretes relaxin and estrogen

57

How does the placental help maintain pregnancy?

Placenta secretes P4

58

What is the placenta's role in pregnancy maintenance?

In the cow, sheep, and mare the placenta takes over from the ovaries at various times.