01:119:116 Lecture 17: Lecture 17 - Development 2
1 Apr 2017
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Document Summary
Sea urchins, frog, chick, human: gastrulation. Highlights - sea urchins are radially symmetrical. Sequence of events: mesenchyme at vegetal pole - migrate to blastocoel, cells at vegetal pole flatten - causing invagination, endoderm cells from archenteron. Produce filopodia (cells that can move: filopodia contract & drag archenteron, archenteron fuses with blastocoel wall. Blastula - open end of archenteron anus. Fig 47. 9: cells on dorsal side invaginate to form blastopore. Ends eventually meet & blastopore forms a circle: sheet of cells spread over animal hemisphere. Animal pole swallows up the vegetal pole, with a little bit of vegetal pole sticking out. Black and pink glove (pink glove is inside) Blastocoel nothing: cells on surface ectoderm. Blastopore surrounds yolk-filled cells: gastrulation in chickens. Initially - embryo forms 2 layers: epiblast form embryo, hypoblast sac around embryo, some epiblast migrate to midline, producing the , primitive streak, gastrulation in humans. Mammalian word for blastula (it sticks to wall and forms a cyst (lump)
