BSCI 207 Lecture Notes - Lecture 16: Neural Crest, Cytokinesis, Developmental Biology
7 Oct 2016
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Cleavage initially begins in the yolk center: a single-cell sheet forms. This single-cell sheet then forms into a flattened blastula: this is the end of the cleavage stage. Gastrulation: a black/dark spot forms at the posterior end of the flat blastula. Forms a primitive streak that travels from the posterior to the anterior. As a result of the loosening of cells; cells are migrating under the epiblast (which ultimately forms the ectoderm: the first cells to ingress will comprise the endoderm. Somites are mesodermal balls : gastrulation is typically coupled with other processes such as neurulation. Neurulation is the beginning of the central nervous system. Forms a neural fold through this process: Ectodermal sheet rolls up/thickens: caused by cell shape changes. Ectoderm makes contact with itself and creates a neural tube: ultimately becomes the spinal cord. Neural crest cells are also developed: 4th germ layer, makes cartilage and bone, specific to vertebrates.
