placenta and fetal membrane Flashcards
fetal component and maternal component of placenta is derived from
fetal- trophoblast and extraembryonic mesoderm (chorionic plate)
maternal- uterine endometrium
changes in beginning of 2nd month
secondary and tertirary villi develop and give a radial appearance
( stem villi extend from extraembryonic mesoderm into the cytotrophoblast shell)
surface of villi is formed by
synyctium which rest on a layer of cytotrophoblast and covers a core of vascular mesoderm
extraembryonic vascular system
capillaries system developing in core of villus come in contact with the chorionic plate and the connecting stalk and makes the extraembryonic vascular system
maternal blood to placenta is delivered by
spiral arteries
endovascular invasion
erosion of maternal vessels to release blood into the intervillous system is done through endovascular invasion by cytotrophoblast
how endovascular invasion is done?
cytotrophoblast released from the ends of villous replace endothelial cells of spiral arteries with hybrid vessels which contains both maternal and placental cells. cytotrophoblast undergo a epithelial to endothelial transition which transform the high resistance small diameter spiral arteries into low resistance more diameter vessels.
chorion frondosum
early developmental days the villi surrounds the whole chorion but as pregnancy advances villi on embryonic pole enlarges and expand give rise to chorion frondosum (bushy chorion)
chorion laeve
at the aembryonic pole villi degenerate and by third month this side of chorion is smooth known as chorion laeve
decidua basalis
the decidua over the chorion frondosum is known as decidua basalis and has decidual cells. also called decidual plate which is tightly connected to the chorion and has lipids and glycogen
decidua capsularis
the decidua over the aembryonic layer is decidua capsularis
decidua parietalis
the chorion leave comes in contact with uterine wall (decidua parietalis) from opposite sides fuse together and obliterate the uterine lumen
only portion of chorion participating in exchange are
chorion frondosum and decidua basalis makes up the placenta
amniochorionic membrane
made by fusion of amnion and chorion makes the amniochorion membrane that obliterates the chorionic cavity and ruptures during birth
placenta has 2 components in the beggining of what month
4 month
the fetal component made by chorionic plate
and the maternal component made by decidual plate
junctional zone of placental and maternal areas
here the trophoblast and decidual cells intermingle
zone is characterized by giant decidual and syncytial cells with amorphous ecm
decidual septa? formation in what month
4 to 5 months
there are many septas made by the decidua in the intervillous spaces but they are not in contact with the chorionic plate
they have a core of maternal tissue and are covered by syncytial cells so at all times the maternal blood is separated from the fetal tissues of the villi
cotyledons
decidua septa divide the intervillous space into cotyledons
4 layers of placental membrane
- endometrium covering the fetal vessels
- connective tissue making the core of villous
- cytotrophoblast
- syncytium
how the rate of exchange of placenta is increased
the endothelial lining of vessels come in close contact with the syncytium which thins the placental membrane
how much 02 does fetus extracts
20-30 ml of oxygen from maternal blood
what is critical to oxygen supply to fetus
placental blood flow and depends on delivery not diffusion
progesterone is produced by placenta at what month
at 4 month to maintain corpus luteum
all hormones are produced by in placenta?
syncytial trophoblast
