Morphogenesis As a Parallel of Invasion: the Epithelial-mesenchymal Boundary and Basal Lamina in Foetal Rat Colon

In order to determine whether neoplastic invasion, as it occurs in colonic carcinoma, represents a recapitulation of embryonic events, the development of the crypts and basal lamina of the rat colon was examined in foetuses between 16 and 21 days gestation by light and transmission electron microscopy, autoradiography and morphometric techniques. The thickness of the basal lamina increased from days 16 to 18 of gestation. On days 19 and 20 the basal lamina was found to be significantly thicker in the intercryptal areas than at the base of the crypt. This difference disappeared at 21 days gestation. It was also demonstrated that cell migration and renewal occur in the same manner in the foetal colon as in the adult colon. These features do not resemble closely those seen in neoplastic invasion.