Between stages 8+ and 12, the near doubling of surface area in each of these domains How do the domains of both neural plate and epidermis manage to double surface areas duringĪt stage 12, both neural plate and epidermis are just one cell thick in salamander and amnioteĮmbryos. In length, and each ectodermal domain has doubled its surface area. Half of the surface, and the epidermis the ventral half.ĭuring gastrulation, the boundary between neural plate and epidermis of the blastula stage doubles By stage 12, neural plate occupies the dorsal Mesoderm and endoderm go inside the embryo. (Twitty and Bodenstein stages 9 to 12 for Taricha torosa)įuture neural plate and epidermis remain on the surface, and their domains are extended as the Laterally at stage 11, and by stage 12, the blastopore is completed ventrally to make the large yolk Rolls inward around the lip, and endoderm rolls inward beneath the lip. Gastrulation starts at stages 9 and 10 as the dorsal lip (DL) of the blastopore forms, mesoderm DL = site of initiation of the dorsal lip.Īt this blastula stage (8+), both prospective neural plate (NE) and epidermal (EE) areasĪre several cells thick and overlie the blastula cavity, the blastocoel. The rest of the spherical surface is occupied by future mesoderm non-neural ectoderm, EE) occupies an adjacent quadrant of the Prospective neural plate (NE) occupies one quadrant of the surface of the sphericalīlastula prospective epidermis (i.e. There is no information for the salamander, but the timing is likely similar.įate maps on the blastula define the areas that will later become neural plate, epidermis, mesoderm,Īnd endoderm. 196:79-90) found that the position of the anterior edge of the neural plate is fixed in the blastula of the Xenopus embryo before gastrulation commences at stage 9. How early in development are these boundaries established? Zhang and Jacobson (1993) (Devel. Three conditions are invoked at the boundaries: (1) cells do not mix across the boundary, (2) cells that contact the boundary are trapped there by contact inhibition, yet adhere to the other cell type, (3) cells from both sides of the boundary intercalate with cells of their own kind at the boundary, are trapped at the boundary, and thus extend the length of the boundary. Another boundary is between neural plate and notoplate (that part of the plate that overlies the notochord). One boundary is between future neural plate and epidermis. The Jacobson laboratory was concerned with the problems of neurulationīoundaries between domains of cells are organizing sites for many events of neurulation. This narrative proceeds 'as the embryo develops'.
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