Chapter 3- Second Week of Development Flashcards
% of pregnancies that are extrauterine implantations
~2%
beta hCG levels in extrauterine pregnancies
lower than normal pregnancies
Placenta privia
placenta partially or fully covers uterine os
placenta previa implantation site
inferior segment of uterus near internal os
placenta previa symptoms/risks
bleeding
premature separation of placenta in pregnancy or labor
threatened abortion
bleeding during pregnancy that increases the chances for abortion
Threatened abortions:
% of all pregnancies
% of TA pregnancies that end in abortion
25% of all pregnancies
50% of TA pregnancies end in miscarriage
Embryonic disc characteristics
- bilaminar
- forms epiblast and hypoblast
- gives rise to all germ layers
End of 2nd week structures formed
amniotic cavity, amnion, umbilical vesicle, connecting stalk, and chorionic sac
Blastocyst implants ___ days after ovulation and ___ days after fertilization
6-10
Maximal blastocyst invasion after ____ days
9-12
Extraembryonic coelom splits into..
extraembryonic somatic mesoderm
extraembryonic splanchnic mesoderm
Extraembryonic somatic mesoderm
lines trophoblast
covers amnion
Extraembryonic splanchnic mesoderm
surrounds umbilical vesicle
prechordal plate forms ____ around _____
the mouth
14 days post fertilization
Most common blastocyst implantation site
superior body of uterus on posterior wall
After 5 days post fertilization…
zona pellucida degrades
After 6 days post fertilization…
blastocyst adheres to endometrial epithelium
After 7 days post fertilization…
trophoblast splits into synctiotrophoblast and cytotrophoblast
After 8 days post fertilization…
blastocyst begins embedding
After 9 days post fertilization…
blood filled lacuane appear in synctiotrophoblast
After 10 days post fertilization…
blastocyst sinks beneath endometrial epithelium
After 10-11 days post fertilization…
lacunar networks form
After 11-12 days post fertilization…
uteroplacental circulation is established
