CMMB 403 Lecture Notes - Lecture 18: General Permitted Development Order, Parallel Array, Primitive Streak
29 Dec 2018
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The organizer in amphibians is the dorsal lip of the blastopore. The actual structures that serve as an organizer varies, for example, mammals don"t have a blastopore. The first cells to pass through the organizer form the anterior (or dorsal) structures and they also express wnt inhibitors, which are necessary to induce anterior (head) structures such as the brain. Cells that become more ventral structures gastrulate through other areas of the blastopore (amphibians), blastoderm margin (fish) or primitive streak (birds and mammals) Gastrulation begins when the dorsal lip forms. Need bmp inhibition to make nervous system. Having multiple organizers will cause organism to form multiple axes, and thus multiple heads. Done by taking tissue of organizer and injecting it elsewhere in embryo. Cellular identity changes as cells pass through the dorsal lip. Dorsal lip disappears as nervous system begins to form.
