Flashcards in Placenta Yan Deck (42)
What makes up a blastocyste?
an inner cell mass and outter cell mass (trophoblast)
What happens on day 6 of fertilization?
trophoblast cells of blastocyst invades uterine epithelium
What happens on day 8 of fertilization?
trophoblast splits into 2 layers, the outter synctrophoblast and inner cytotrophoblast
What happens on day 9 of fertilization?
fibrin coaglum develops
trophoblast is in lacunar stage
primitive yolk sac forms
What is the closure of the penetration defect called?
the fibrin coagulum
How do we get to the lacunar stage?
On day 9: vacuole formation-> fusion -> lacunae
What happens on Day 11 and 12 of fertilization?
establishment of uteroplacental circulation
(maternal blood enters)
How do we get uteroplacental circulation?
trophoblast lacunae-> meet with maternal sinusoids-> maternal blood enters the lacunar system
What happens on day 13 of fertilization?
Primary villi fomration
How do we get primary villi formation?
cytotrophoblastic cells will proliferate and penetrate into synctiotrophoblast which create columns and make villi
How do we get secondary villus formation?
mesodermal cells penetrate the core of 1st villi
How do we get a tertiary villus formation?
mesoderm cells become blood cells and blood vessels
At the end of the third week, what happens?
maternal vessels penetrate cytotrophoblastic shell and enter intervillous space
At the third week, maternal vessels penetrate cytotrophoblastic shell and enter intervillous space. These capillaries in the villi are in contact with what?
with vessels in chorionic plate and connecting stalk which are connected to intraembryonic vessels
At the end of the 3rd week what happens?
the secondary and tertiary vills give the trophoblast a radial shape.
What are the intervillous spaces lined with?
At the end of the the third week, (blank) surround the entire trophoblast and are in contact with the endometrium.
The embryo is suspended in the chorionic cavity by the (blank)
What makes up the placental membrane of the placenta in the fourth week?
What makes up the placental membrane of the placenta in the fourth month?
By the end of the 2nd month, what disappears and where?
villi at the abembryonic pole forming chorion laeve
By the end of the 3rd month, what happens?
amnion and chorion fuse
uterine cavity is obliterated
How does the uterine cavity become obliterated in the third month?
by the fusion of chorion laeve and deciuda parietalis
How big is a full-term placenta?
15-25 cm diameter, 3 cm thick, 500-600g
How long does it take for the placenta to shed off the uterine wall after birth of child?
What are the components to the fetal side of a full-term placenta?
amnion, umbilical cord, chorionic plate, chorion vessels
What are the components to the maternal side of a full-term placenta?
cotyldon and decidua basalis
How do you get dizygotic twins?
you ovulate 2 eggs at the same time
How do you get monozygotic twins?
one egg splits into 2