Biology 3338A Lecture Notes - Lecture 12: Neural Plate, Surface Ectoderm, Sonic Hedgehog
24 Jan 2015
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Document Summary
Different body regions induce different neural tissues (related to underlying endoderm, notochord, etc) Formation of neural plate & shaping of neural plate. Bending of neural plate and formation of neural groove. Closure of neural groove to form neural tube. Formation and shaping of neural plate dorsal mesoderm signals ectodermal cells to elongate into columnar neural plate cells. R meso ant plate lengthen along a-p axis. Need border regions of presumptive epidermis to form tube. In birds and mammals medial hinge point cells (mhp) form anterior to. Henson"s node -mhp anchored to notochord -> inductive signals. Folds meet at dorsal midline - adhere and fuse. Neural crest cells formed as fusion occurs (in mammals cranial neural crest cells migrate before closure) Dorsal mesoderm and neural tissues are induced in a wave from anterior to posterior. Other shape changes also occur during closure -> cephalic cells broaden. As tube closes anterior and posterior neuropores formed.
