Fertilization, Maternal Recognition of Pregnancy and Placentation

Question 1

What needs to occur for fertilization?

Answer 1

Sperm needs to encounter oocyte

Question 2

What is the general range of sperm viability?

Answer 2

Hours to days

Question 3

Roughly how much sperm is lost via retrograde flow?

Answer 3

~50%

Question 4

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

Answer 4

The cervix

Question 5

Where is capacitation initiated?

Answer 5

The uterus.

Question 6

Where is capacitation completed?

Answer 6

The oviduct.

Question 7

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

Answer 7

The acrosome reaction.

Question 8

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

Answer 8

Pig
Alpaca
Horse

Question 9

In what 5 species is semen deposited in the vagina?

Answer 9

Cows
Goats
Sheep
Dogs
Cats

Question 10

Where do sperm mature?

Answer 10

Through the epididymus

Question 11

Where is maximal sperm fertility achieved?

Answer 11

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

Question 12

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

Answer 12

Capacitation

Question 13

What is the rapid phase of sperm transport?

Answer 13

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

Question 14

What is the sustained phase of sperm transport?

Answer 14

Sperm delivered continually from reservoirs.

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

Question 15

What 2 areas are considered “reservoirs” for sperm?

Answer 15

Cervix

Uterotubual junction

Question 16

What is the site of fertilization?

Answer 16

The Ampullary-isthmic junction

Question 17

What is capacitation?

Answer 17

Stripping of the seminal plasma proteins by uterine factors.

Question 18

What is the result of capacitation?

Answer 18

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

Question 19

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

Answer 19

Cumulus cells
Zona Pellucida
Oolemma (oocyte membrane)

Question 20

What is the function of the zona pellucida?

Answer 20

Prevents polyspermy

Question 21

What initiates the acrosome reaction?

Answer 21

Binding of the sperm to the zona pellucida.

Question 22

How is polyspermy prevented?

Answer 22

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

Question 23

What is syngamy?

Answer 23

Fusion of male and female pronuclei to form a zygote.

Question 24

How many cells are in a zygote?

Answer 24

One

Question 25

How many cells are in an embryo?

Answer 25

Many

Question 26

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

Answer 26

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

Question 27

What is the site of fertilization in the cow?

Answer 27

The ampullaristhmic junction.

Question 28

What is totipotency?

Answer 28

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

Question 29

Up to what stage is each blastomere totipotent?

Answer 29

8-16 cell stage

Question 30

How many cells are in a morula?

Answer 30

16+ cells

Question 31

What is the first fetal membrane you see at birth?

Answer 31

Amnion

Question 32

Why do you not see the chorion first at birth?

Answer 32

Because it is attached to the dam.

Question 33

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

Answer 33

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

Question 34

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

Answer 34

Preservation of the primary CL | Maintain high levels of progesterone

Question 35

What must maternal recognition of pregnancy occur before?

Answer 35

Before luteolysis

Question 36

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

Answer 36

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

Question 37

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

Answer 37

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

Question 38

What is so different about equine maternal recognition of pregnancy?

Answer 38

The embryo needs to migrate everywhere to signal pregnancy.

Question 39

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

Answer 39

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

Question 40

What membrane is the origin of the placenta?

Answer 40

The chorioallantois.

Question 41

What type of placenta does a horse have?

Answer 41

Diffuse NOTE: Sow also has diffuse

Question 42

What type of placenta does a ruminant have?

Answer 42

Cotyledonary

Question 43

What type of placenta does a primate have?

Answer 43

Discoid

Question 44

What type of placenta does a dog or cat have?

Answer 44

Zonary

Question 45

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

Answer 45

Chorionic villi

Question 46

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

Answer 46

6 layers total; 3 maternal and 3 fetal NOTE: Embryo ALWAYS has 3 layers.

Question 47

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

Answer 47

5 layers total; 2 maternal and 3 fetal NOTE: Embryo ALWAYS has 3 layers.

Question 48

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

Answer 48

4 layers total; 1 maternal and 3 fetal NOTE: Embryo ALWAYS has 3 layers.

Question 49

What type of placenta does a sow have?

Answer 49

Diffuse

Question 50

What 6 species have an epitheliochorial placenta?

Answer 50

``` Pig Horse Camelid Cow Sheep Doe ```

Question 51

What 2 species have an endotheliochorial placenta?

Answer 51

Dog | Cat

Question 52

What 2 species have a hemochorial placenta?

Answer 52

Primates | Rodents

Question 53

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

Answer 53

Endometrial cups

Question 54

What is produced by the endometrial cups?

Answer 54

Equine chorionic gonadotropin (eCG)

Question 55

How does the placental induce parturition?

Answer 55

Convets P4s to estrogen

Question 56

How does the placenta assist parturition?

Answer 56

Secretes relaxin and estrogen

Question 57

How does the placental help maintain pregnancy?

Answer 57

Placenta secretes P4

Question 58

What is the placenta's role in pregnancy maintenance?

Answer 58

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