BIO380H5 Lecture Notes - Homeobox, Blood Vessel, Chordin
Document Summary
Neurulation converts presumptive neural ectoderm into neural tube: progenitor of brain and spinal cord. Neural crest migrate down to form specialized tissues. The primary germ layers chordamesoderm push though the node during gastrulation then embeds within the endoderm. During neurulation chordamesoderm will separate to presumptive notochord. Induction of neural tissue by chordamesoderm the node has role in organizing overall body plan the chordamesoderm signals the above ectoderm to become presumptive neural ectoderm. Historically cutting and pasting embryo tissue studies tissue interaction removal of node - no neural tissue, no neural axis transplanting node - 2nd neural axis. Primary induction - tissue in node induce primary embryonic axis in mammals the node requires other tissues to be fully effective. Genes and head development the node secrets molecules for head formation. Noggin and chordin are genes expressed by node. Neural tube is one layer cell thick thickens at the head to form folds. New layers of nerve cells appear (neurogenesis)
