Female Histology 5 Flashcards
Describe the origin and structure of a placental villus and placental membrane (maternal/fetal blood barrier).
1
Q
What is the role of the placenta?
A
- physiological exchange between mother and fetus
- also an endocrine organ:
- HCG
- estrogens
- progesterone
- renin
- human placental lactogen (HPL)
- thyroptropic substance
2
Q
Describe the makeup and histology of the umbilical cord.
A
- mucous connective tissue
- connects placenta to fetus
- contains two umbilical arteries (deoxygenated blood)
- umbilical vein (oxygenated blood)
- yolk sac
- allantois
3
Q
Describe the histology of the chorionic villous.
A
- Fetal part of placenta
- branching structure composed of the three layers of the blastocyst chorion
-
outer syncytiotrophoblast
- endocrine layer in contact with maternal blood
- manufactures and secretes HCG
- cytotrophoblast - mostly disappears during late pregnancy
-
mesodermal core - extra-embryonic
- forms connective tissue in which fetal vessels develop
-
outer syncytiotrophoblast
4
Q
Describe the histology of the decidua basalis.
A
- maternal part of the placenta
- contain blood vessels which upen into lacunae surrounding fetal villi
5
Q
Describe the histology of the placental membrane (maternal-fetal blood barrier).
A
-
Sequential layers:
- syncytiotrophoblast
- cytotrophoblast (when present)
- basal lamina of cytotrophoblast
- mesenchyme of the villus
- basal lamina of fetal capillaries
- endothelium of fetal capillaries
- late in pregnancy the membrane thins as the cytotrophoblast disappears and the two basal laminae fuse as the capillaries press against the syncytiotrophoblast