Embryology and Maternal Recognition of Pregnancy

How long does it take for the zygotre to form?

24hrs

The outer cells of the early embryo have _______ that pump _____ into the center of the morulla

Na+ pumps: sodium

The outer layer of the morula becomes the ______ in the blastocyst stage

trophectoderm

What are the extra-embryonic membranes of the pre-attachment embryo?

Yolk sac

chorion

amnion]

allantois

After the primitive endoderm completed growth, the _____ forms

tolk sac

What is the second differentaation event?

formation of primitive endoderm

What fuses to form the chorion?

trophectoderm and mesoderm

What is the allantois

primitive gut

True or False: The allantois and yolk sac grow togteher

FALSE - allanotois growth makes yolk sac regress

The fusion of the chorion around the embryo makes the _____

amniotic sac

What prevents the female from going back into cycle?

CL producing progesterone

True or False: Cats are induced ovulators and will not have a CL if they do no have copulation.

TRUE

Is recognocition of pregnancy required in the dog?

NO - CL is maintained until birth

What causes luteolysis in ruminant?

PP releasing oxytocin which stimulates PGF2a

CL regresses and P4decreases causing return to cyclicity

In order to recognize pregnancy in the cow and ewe, they secrete ______

interferon-tau

What does interferon tau do?

blocks production of oxytocin receptors which blocks PGF2a

What cells secrete interferon tau

trophoblast

In sows, they secrete _____ for maternal recognition of pregnancy.

estradiol

Thre must be embryos in both uterine horns by day ______ to maintain pregnancy in sows

10-12

What is the function of estradiol in maternal recognition of sows?

reroutes PGF2a away from capillaries and into the uterine lumen

What causes maternal recognition in mares?

Travel of conceptus through the entire uterus which prevents PGF2a

How do humans have maternal recognition of pregnancy?

hCG which stimulates CL growth and increased levels of P4 to block PGF2a

What are the five stages of concepteus attachment?

1. shedding of zona pellucida and initiation of elongation

2. Downregulation of MUC1 on surface of uterine luminal epithelium

3. Stronger connections between conceptus and epithelium to mediate apposition

4. Integrin receptors bind and build bridges between conceptus and uterus during adhesion

5. Microvilli develop between uterine LE and TE to stabilize it which facilitates nutrient and gas exchange

What secretes histotroph?

uterine glands

What species has embryo transfer been successfully done in?

ctas, dogs, horses, cattle, sheep, goats, pigs

Ovulation synchronization steps

1. CIDR secretes low levels of P4

2. PGF21 induces luteolysis

3. cow comes quickly into heat