Health Sciences 4320A/B Lecture Notes - Lecture 4: Decidua, Syncytiotrophoblast, Hypoblast
11 Feb 2020
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Placenta: placenta cells surround the entire conceptus. Helps establish a mechanism for a metabolic connection between baby and maternal blood supply: chorionic frondosum. Contributed by fetal tissue cells, grows from trophoblast cells. Invades into uterine wall and creates pockets (decidua basalis: decidua basalis. Uterine cells that have been triggered to form the placenta. Day 8: blastocyst is partially embedded into uterine lining by this day. Implantation takes place during day 6-10 and complete by end of second week. Cytotrophoblast inner layer, migrates into the syncytiotrophoblast. Invades endometrial tissue, embryo starts to embed in the endometrium. Syncytiotrophoblast cells displace endometrial cells, causing apoptosis. Syncytiotrophoblast absorbs nutrients from the dead cells. Produces hcg maintains hormonal activity of corpus luteum: amnion cells pump amniotic fluid which creates the amniotic cavity. Acts as cushion to avoid shock to embryo. Epiblast thicker columnar cells, related to the amniotic cavity. Goes on to form the embryo proper. Helps with orientation (e. g. , frontal, dorsal, etc. )
