Embryology 3 - The Early Fetal-Maternal Circulation Flashcards
By the 4th week, what has the growth of the embryo and chorion resulted in?
Diffusion of nutrients between the embryo and endometrium being INADEQUATE
What day does the embryonic heart begin to beat?
Day 21
What are present in the embryo by day 21?
Blood vessels and RBCs
What two things does maternal-fetal circulation depend on?
- Fetal cardiovascular system
- Structures in endometrium that allow exchange to happen
What are primary chorionic villi composed of?
Cytotrophoblasts surrounded by synctiotrophoblastic shell
What are secondary chorionic villi composed of?
Extraembryonic mesenchymal core surrounded cytotrophoblastic AND syncytiotrophoblastic shell
When are tertiary chorionic villi present?
By the end of week 3
Because of tertiary chorionic villi, fetal blood can now exchange blood with maternal _______ through the membrane formed by the villus
Lacuna
As the villi develop, what is formed as the cytotrophoblast proliferates and extends through the syncytiotrophoblast layer?
Cytotrophoblastic shell
What is the function of the cytotrophoblastic shell?
Anchors the chorionic sac and attaches it to the endometrium
What is an anchoring villus?
villus that attaches to endometrium via cytotrophoblastic extensions
That is the endometrium in a pregnant woman?
decidua
What are the 3 separate areas of the decidua?
- Decidua basalis
- Decidua capsularis
- Decidua parietalis
The decidua that forms the placenta, thats connected to the embryo by the umbilical cord?
Decidua basalis
The decidua that doesn’t include the basalis, but is still associated with/covers the embryo?
Decidua capsularis
Decidua that is formed by the endometrium that is not a part of the embryo (far from implantation site)?
Decidua parietalis
The chorionic membrane that is associated with the decidua capsularis?
Smooth chorion
Where is maternal blood found in the pregnant uterus?
Intervillous spaces
Where does the development of the fetal cardiovascular system begin?
Umbilical vesicle and neighbouring connecting stalk
When does fetal cardiovascular system begin to develop?
Early in the 3rd week
What is vasculogenesis?
Development of brand new blood vessels from mesoderm
What is angiogenesis?
sprouting of blood vessels formed by vasculogenesis - connects blood vessels to each other
Angioblasts derives from ______ develop specialized regions known as ________
Mesoderm; blood islands
What is the process of blood islands developing luen and becoming blood vessels called?
Vasculogenesis
Blood cells are derived from the what of the new vessels?
Inner lining (endothelium)
Extraembryonically, what do blood cells develop from?
Endothelium of allantois and umbilical vesicle
Intraembryonically, what do blood cells develop from?
Endothelium of dorsal aorta
Within the embryo, the formation of angioblastic cords (vasculogenesis) occurs where during gastrulation/nurulation?
Mesenchyme
The caudal head fold brings the paired heart tubes ______ toward the _______
Caudally, toward the umbilical vesicle
When do the heart tubes fuse to from a primordial heart tube?
At the end of the third week
What does the intraembryonic coelom near the heart tube develop into?
The Pericardial Cavity
Vessel that supplies blood to the embryo and then connects to the umbilical artery and cardinal veins?
Dorsal aorta
The flow from dorsal aorta to cardinal veins feeds what?
Intraembryonic tissues
Vessel responsible for Blood flow through the umbilical vesicle?
Vitelline artery and vein
vessel that returns blood from the tertiary villi back to the embryonic heart?
Umbilical vein
