Placentation and immunology Flashcards
Extraembryonic sacs include ….
Extraembryonic sacs include the amnionic and the yolk sacs.
describe the amnion
The amnion is a membrane that creates a fluid-filled sac in which the embryo/fetus is suspended.
It provides a protective environment for the fetus to develop.
describe the yolk sac
The yolk sac is a structure outside of the developing embryo and is connected by the yolk stalk. It is vascularized with fetally-derived vessels, and is involved in nutrient uptake, protein synthesis, and is the first site of hematopoiesis.
It transports nutrients, such as amino acids and glucose, from the fluid in the extraembryonic coelom for fetal use.
describe the outer surface of the yolk sac
The outer surface of the yolk sac is like an absorptive epithelium with microvilli. The glucose transporter GLUT1 (and other nutrient transporters) are present on this outer surface.
alpha-fetoprotein?
where is it produced, and what does it do
The yolk sac also synthesizes proteins including alpha-fetoprotein. An increased level of alpha-fetoprotein in the maternal circulation indicates abnormal placental permeability and pathology or fetal death
While the ________ is maintained throughout pregnancy, the _________ regresses by 20 weeks of pregnancy when the placenta is established.
While the amnion is maintained throughout pregnancy, the yolk sac regresses by 20 weeks of pregnancy when the placenta is established.
Around the time of implantation, the inner cell mass is divided into two layers
what are they?
Around the time of implantation, the inner cell mass is divided into two layers, the epiblast and the primitive endoderm (also known as hypoblast)
The dorsal surface of the epiblast faces the ________ whereas the primitive endoderm faces _________
The dorsal surface of the epiblast faces the amnionic cavity whereas the primitive endoderm faces the blastocoel.
do you understnad the cahnges in:
teh extraembryonic cavity
the yolk sac
the amnion

As development continues, the amnion expands around the ventral surface of the embryo and by 12 weeks of pregnancy, the amnion pushes against the inner surface of the _______, obliterating the extraembryonic coelom.
As development continues, the amnion expands around the ventral surface of the embryo and by 12 weeks of pregnancy, the amnion pushes against the inner surface of the chorion, obliterating the extraembryonic coelom.
The yolk sac becomes connected to the embryo via the ….
The yolk sac becomes connected to the embryo via the yolk sac stalk.
the placenta does lots of roles.
give some exampes
For example,
gas transfer (lung);
excretory functions,
water balance,
pH regulation (kidney);
catabolic and resorptive function (gut);
synthetic and secretory functions (most exocrine glands);
metabolic functions (liver);
haematopoiesis (bone marrow);
and immunological interations and protection (immune system).
dimentions of the placenta?
The mature placenta is a discoid organ that is 20-25 cm in diameter and weighing 400-600 g.
The side of the placenta that faces the fetus is called the…
The side of the placenta that faces the fetus is called the chorionic plate
The basal plate of the placenta is apposed to the ____ _______ (maternal tissue that is formerly the endometrial stroma).
The basal plate is through which the maternal blood enters the placenta
The basal plate of the placenta is apposed to the decidua basalis (maternal tissue that is formerly the endometrial stroma). The basal plate is through which the maternal blood enters the placenta
The functional unit of the placenta is called the …
The functional unit of the placenta is called the fetal villus tree
The functional unit of the placenta is called the fetal villus tree, which arises from the _____ _______ and consists of …..?
The functional unit of the placenta is called the fetal villus tree, which arises from the chorionic plate and consists of two layers of trophoblast cells (syncytiotrophoblast and cytotrophoblast) surrounding fetal capillaries.
The first cells of the placenta appear at the blastocyst stage of the embryo as ________
The first cells of the placenta appear at the blastocyst stage of the embryo as trophectoderm
describe how trophoectoderm cells being the formation of the placenta
At implantation, the trophectoderm attaches to the endometrial epithelium and invades between the cells. Two trophoblast cell populations form: an inner layer of mononuclear cells called cytotrophoblast cells and an outer multinucleated layer called syncytiotrophoblast
Two trophoblast cell populations form: an inner layer of ______________ cells called cytotrophoblast cells and an outer ___________ layer called syncytiotrophoblast
Two trophoblast cell populations form: an inner layer of mononuclear cells called cytotrophoblast cells and an outer multinucleated layer called syncytiotrophoblast
Syncytiotrophoblast are ___________ cells that are generated by ….?
Syncytiotrophoblast are non-proliferative cells that are generated by continual fusion of cytotrophoblast cells.
spcaes called what form within the syncytiotrophoblast?
lacunae
after the formation of lacunae, what hapens nect regarding placental formation
the syncytiotrophoblast cells form trabeculae between the lacunae into which the cytotrophoblast cells and extraembryonic mesoderm penetrate.
This results in the earliest placental villi.
Side braches from the trabeculae form into the lacunae. These gradually branch again to become more complex. Repeated branching forms the placental villus tree.
The lacunae are now referred to as the….
Side braches from the trabeculae form into the lacunae. These gradually branch again to become more complex. Repeated branching forms the placental villus tree.
The lacunae are now referred to the intervillus space











