ANAT 2130 Lecture Notes - Lecture 5: Motility, Recto-Uterine Pouch, Blastocyst
16 Oct 2016
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Document Summary
Cleavage and blastocyst formation formation occurs on way to uterus. Pregnancy tests accurate within 7 days of fertilization via sensitive laboratory tests for blood hcg. Home test kits less sensitive colorimetric assays soon after missed period, can detect hcg in urine. Hcg stimulates continued progesterone secretion by corpus luteum. Blastocyst attaches at pole containing inner cell was. Outer trophoblastic cells proliferate and fuse to form outer sanctum. Results in formation of inner cytotrophoblast (ctb) and superficial synctiotrophoblast (stb) Stb breaks down endometrial epithelium and degrades stroma. Stb continues to invade and expand, forming irregular surface with lacunae = surface irregularities. Hemochorial placenta: free surface of pre-embryo (chorion) bathed directly in maternal blood. Human implantation is interstitial: pre-embryo completely surrounded by maternal tissue. This prevents loss of maternal blood into uterine cavity. An abnormal implantation: one that occurs in any site other than the upper, posterior portion of the uterine body.
