Vital dye mapping of the gastrula and neurula of Xenopus laevis

Abstract

The disposition of prospective areas and the course of morphogenetic movements during gastrulation and neurulation were investigated by vital staining. The prospective lining of the archenteron, the prospective neural area, and the prospective epidermal area are represented on the surface of the early gastrula. The prospective lining of the archenteron occupies the area within 65–70° of the vegetal pole and is divided into prospective archenteron roof and prospective archenteron floor by the blastopore pigment line which functions as the locus of invagination. A crescent-shaped neural area lies immediately above the prospective archenteron roof, rising from it at 125° lateral to the dorsal midline to a point 130° above the vegetal pole in the dorsal midline. In the early gastrula, most, if not all, mesoderm is deep to the surface layer and is mapped by the insertion of dyed agar spikes. Results thus far indicate that the prospective notochord lies in the dorsal deep marginal zone, followed laterally by the medial region of the somites, the lateral region of the somites, and the lateral plate. The morphogenetic significance of the comparative disposition of the anlagen in Xenopus is discussed.