Rearrangement of the morphological structure and degradation of the extracellular matrix in amphibian embryos after short-term disruption of cell contacts

The changes in cell structure of explants of presumptive early gastrula mesoderm of Xenopus laevis and dynamics of extracellular matrix formation has been studied for 6 h after their isolation. After 6 h, control explants of any dorsoventral level turned into dense spheric homogeneous cell clusters. Explants of dorsal and lateral sectors, treated with medium without Ca2+ and Mg2+ for 30 s, bent and separated into several layers, and in ventral sector explants, cavities, surrounded by polarized cells, arose. In control explants, the amount of extracellular matrix on the surface and in intercellular spaces increased, and in the experimental explants, extracellular matrix disappeared and was not observed for several hours. Previously described differential transformations of the treated explants (Georgiev, Belousov, 1986) are supposed to be determined by extracellular matrix degradation and the degradation-associated complications of cell structure of the explant.