Establishment of Pregnancy Flashcards
When does the embryo enter the uterus?
after fertilization
How long does it take an embryo to enter the uterus in:
Swine
Cattle
Mares
Swine: 48-56 hrs
Cattle: 72 - 96 hrs
Mare: 144 hrs
At 5-6 days of development, where is the embryo and what is it called?
uterus, morula
how long until the blastocyst fully forms?
7-9 days
How long is the gestation period of swine?
115 days
How long is estrus? (swine)
48-72 hrs
What does the loss of corpus luteum function lead to? (swine)
abortion within 36 hrs
When does a blastocyst form in swine?
day 5
When does hatching occur in swine?
day 6-7
When does the ovoid form arise in swine?
day 10
When does the filamentous form arise in swine?
day 16
What happens on day 16
- Estrogen production causing uterine secretions of protein, PGF2alpha, PGE2 and plasminogen activator
What does the blastocysts escape from the zona provide?
the first cell to cell contact between the conceptus and maternal uterine epithelium
Why must the conceptus physically cover a large portion of the maternal endometrium?
to regulate the release of prostaglandin F2alpha to prevent luteolysis
When does the conceptus undergo a rapid process of trophoblast elongation?
day 12
What is migration and equal spacing modulated by?
peristalic contractions of the myometrium stimulated by the developing conceptus
- conceptus production of histamine, estrogen and prostaglandins all play role in stimulating local myometrial activity to move conceptus
What is unique about the equine conceptus following hatching from its zona pellucida?
it is surrounded by an acellular capsule that forms between the trophoblast and zona when the embryo enters the uterus on day 5.
What does the acellular capsule surrounding the equine conceptus do?
- may play a role in migration and protection of the conceptus
Why does the equine vesicle migrate so much between the uterine horns?
- essential for inhibition of luteolysis
What does the conceptus production of prostaglandin involved in?
stimulating myometrial contractility to propel the vesicle through the uterine horns
What is induced by conceptus production of estrus? What does it cause?
increase in uterine diameter, uterine tone, and thickening of the uterine wall - causes fixation of vesicle within the uterine lumen on day 16 of gestation
- uterine secretions
- maintenance of CL during early pregnancy
What is the proper orientation of the embryo? How is this achieved?
embryo orientated to the ventral region of the vesicle.
- results from regional differences in the chorion thickness as mesodermal layer migrates down between the trophectoderm and endoderm.
- myometrial contractions
What is the embryoblast?
inner cell mass of embryo
How does the embryoblast become exposed to the maternal environment?
degeneration of the trophectoderm covering it
