ANHB1101 Lecture Notes - Lecture 22: Inner Cell Mass, Amniotic Sac, Epiblast
5 Sep 2018
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Induction mechanisms (signal from adjacent tissues to induce change) Folding (rearrangement of at layers into tubes within tubes). = 2 cells to 4 cells to 8 cells. Trophoblast surrounds blastocyst (cell layer) - forms embryonic part of placenta. inner cell mass forms the embryo. blastocyst then hatches from zone pellucida to implant. Also releases hormone (hcg) which signals that implantation is occurring which starts physiological changes in the mother. Regular trophoblasts are now called cut-trophoblast to indicate they are single cells different from the others. Syncytiotrophoblast has lacunae (gaps) that ll with uterine milk" to provide support for developing embryo (nutritional). Foetus side of placenta formed by trophoblast cells (the 2 types above). Epiblast (outer layer) and hypoblast (inner cell layer) In epiblast another uid lled cavity begins to form. 9 days = amniotic membrane (formed from epiblast cells) begins to form to enclose the amniotic cavity. Hypoblast cells form yolk sac. embryonic disc = epiblast and hypoblast.
