Pregnancy and Development

Pregnancy and Development - Pregnancy and Development...

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Pregnancy and Development Tuesday, April 15, 2008 5:46 PM Placentation 1. Refers to the formation of a placenta , a temporary organ that originates from both embryonic and maternal tissues 2. Chorion- cells from the original inner cell mass give rise to a layer of extra embryonic mesoderm that lines the inner surface of the trophoblast o Becomes the CHORIONIC VILLI 3. The continuous erosion produces blood filled lacunae, or intervillus spaces , in the stratum functionalis of the endometrium. 4. Decidua Basalis- part of the endometrium that lies between the chorionic villi and stratum basalis 5. Decidua Capsularis - surrounding the uterine cavity face of the implanted embryo 6. Placenta produces: human placental lactogen, human chorionic thyrotropin and relaxin. Events of Embryonic Development: Gastrula to Fetus 7. Blastocyst is converted to gastrula , in which the three primary germ layers form, and the extraembryonic membranes develop. Before becoming three-layered, the inner cedll mass first subdivides into two layers- the upper epiblast and the lower hypoblast Formation and Roles of the Extraembryonic Membranes 8. Extraembryonic membranes - form during the first two to three weeks of development include the amnion, yolk sac, allantois, and chorion. 9. Amnion - develops when cells of the epiblast fashion themselves into a transparent membranous sac 10. Amniotic fluid- Membranous sac filled with amnion o Amniotic sac only breaks at the umbilical cord o Protects against trauma and maintains a constant homeostatic temperature
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Pregnancy and Development - Pregnancy and Development...

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