CSB331H1 Lecture Notes - Lecture 14: Neural Crest, Paraxial Mesoderm, Lateral Plate Mesoderm
19 Apr 2017
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Document Summary
Somitogenesis and neural crest cell path nding - lecture 14. Somitogenesis: somites bud o from unsegmented paraxial mesoderm. Somites bud o from the presomitic mesoderm (psm) in an anterior to posterior in direction. Then outer cells undergo met to form an epithelial covering for each somite. Somitomeres whorls of cells - precursors to being segmented. Somites rst in rostral then move towards caudal but they di erentiate in opposite directions, so rst born di erentiate rst. Number of somites is xed (for a species) Somites are speci ed through inhibition of bmp signalling. Paraxial mesoderm expresses he bmp inhibition noggin, secreted from the notochord. If noggin secreting cells are placed transplanted into a region of prospective lateral plate, they re-specify that mesoderm, to form somites (detected by pax3) Mesoderm is patterned by bmp gradient that increases laterally. Bmp signalling decreases from lateral plate mesoderm to neural tube.
