Embryology Flashcards
What is another name for the inner cell mass?
Embryoblast
What is another name for the outer cell mass?
Trophoblast
What is the beginning of implantation?
When the blastocyst attaches to the endometrial epithelium at the embryonic pole
What 2 layers does the trophoblast give rise to?
1) Cytotrophoblast
2) Syncytiotrophoblast
What is the new layer of cells that form on the surface of the inner cell mass at the end of the first week?
Hypoblast
By what day(s), is implantation complete by?
11-12
When can primary villi first be seen?
9 days
When can secondary villi be seen?
11-12 days
Where does implantation normally occur?
Posterior wall of the uterus
How often do ectopic pregnancies occur?
.25-1%
Where is the most likely place for ectopic pregnancies?
Within the uterine tube
What hormone when giving in large doses prevents preganancies from occurring by 1) inhibiting implantation b/c the uterus isn’t ready 2) delaying ovulation 3) inhibiting ovulation 4) preventing fertilization?
Progestin compounds
At what day is there an advanced morula?
4 days
At what day is there a blastocyst?
5 days
What is a transgenic mouse?
Created by injecting the pronucleus with a DNA fragment that then becomes RANDOMLY incorporated into the cell’s genome
What is a gene-targeted mouse?
Created by constructing the DNA fragment in a way that the gene is not only incorporated into the genome but also replaces part of the endogenous gene that matches specific regions of the DNA fragment. “Transfection”
The inner cell mass/embryoblast forms these 2 things?
1) Epiblast
2) Hypoblast
Cells from the yolk sac endoderm and the primitive streak give rise to?
Extraembryonic mesoderm (surrounds the amnion and yolk sac)
What cavities are formed from the syncytiotrophoblast invading the endometrial stroma?
Amniotic and chorionic cavities
What is another term for the hypoblast?
Bilaminar embryonic disc
What cells begin to produce hCG?
Syncytiotrophoblast cells
Where do lacunae appear?
Syncytiotrophoblast
At early stages in development, how do nutrients pass to the embryonic disc?
Diffusion
At what day is the conceptus completely embedded in the endometrium?
Day 10
What days are the lacunar networks establishing the primitive uteroplacental circulation?
12-12.5
The extraembryonic coelom splits the extraembryonic mesoderm into:
1) Somatic Mesoderm
2) Splanchnic mesoderm
Where do primary villi originate from?
Cytotrophoblast and induced by extraembryonic somatic mesoderm
What 2 layers constitue the chorion?
1) Extraembryonic somatic mesoderm
2) 2 layers of the trophoblast
At day 13, what develops from the hypoblast cells?
Prechordal plate
The prechordal plate is the future site of what?
1) Mouth
2) (Important organizer of the head)
When can hCG be assayed in the blood?
Day 8 post fertilization
When can hCG be assayed in the urine?
Day 10 post fertilization