MCD BIO 138 Lecture Notes - Lecture 11: Neural Tube, Germ Layer, Gastrulation
4 Jun 2019
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Lec 11 frog neural tissues & ap axis overview. Invertebrates have closed neural tube, initially formed flat tissue -> cell shape rearrangement: blastopore lip: region of involution. Then region extends ventrally; cells involuting in ventral region become ventral cell types e. g. ventral mesoderm. Embryo elongates nc -> induce dorsal characters of mesoderm -> mesoderm becomes organizer (spemann) -> bmp antagonists -> additional d/v patterning signals -> D/v germ layer derivatives: nc forms in dorsal vegetal cells because overlapping high concentration of maternal determinants (veg-t, vg-1) & b-catenin. Animal cap cells -> mesoderm; closest to nodal-related is most dorsal mesoderm today"s lec: most dorsal cells become organizer (spemann); spot of gastrulation initiation/involution: spemann organizer makes bmp antagonists -> gradient of bmp activity across dv axis. Neural tissues form in ectoderm with low bmp activity; epidermis vice versa.
