DASC20010 Lecture 3: 3
23 Jul 2018
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Document Summary
4 membranes from: trophoblast (trophoectoderm, endoderm, mesoderm. Chorion: derived from troph and mesoderm, mediates attachment to uterus, when broken, pregnancy occurs. Amnion: troph and meso, fluid filled so protects embryo. Yolk sac: endoderm, regresses with time in mammals, contributes primitive germ cells. Allantois: from primitive gut, fluid filled collects waste from embryo, fuses with chorion, allantochorionic membrane, foetal contribution to placenta, surface for attachment to endometrium. 2/3/17: rod-shaped cells located cranial to primitive streak. In midline coelomic space not invaded by migrating mesoderm. Induces formation of head, nervous system and somite formation: future location of vertebral column. Ectoderm above notochord thickens to form neural plate. Plate becomes depressed in midline forming neural groove. Neurulation- initial development of gut, heart and nervous system. Neural plate bound by elevations called neural folds. Neural fold elevates, folds converge to midline, meet and fuse together. Cranial and caudal folds meet at umbilicus. Gut tube formation same as neural tube.
