Biology 3338A Lecture Notes - Lecture 11: Archenteron, Blastocoel, Imz-Ural
22 Aug 2016
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In (a), red is actually endoderm or presumptive mesoderm ie. once endoderm moves, it will become mesoderm. When bottle cells sink in, they resemble bottles with thin apical side and wide basal side. Noticed that endodermal cells opposite sep always sank in to form bottle cells. Inserted sperm on specific site on xenopus egg to establish sep. Put them on endoderm cells in different location ie. not opposite sep. Still sank in to try to undergo gastrulation by becoming bottle cells and forming blastopore groove. So zygotic transcription makes bottle cells express genes that allow them to sink in and start gastrulation. Once gastrulation starts, no longer need bottle cells. Do not know exactly how these cells sink in". Once bottle cells sink in, other endodermal cells ie. dorsal marginal cells start involuting into dorsal lip. Migrate along ectoderm of roof of blastocoel cavity away from posterior towards anterior. Start at dorsal lip where bottle cells sink.
