Abstract
The gingiva and the hard palates of the human embryos from the fourth to the ninth foetal month were used as materials and the attachment between the epithelium and the lamina propria were studied. The materials were fixed in 10% formalin, embedded in paraffin. Six micra thick sections were made vertically and parallel to the surface of the mucous membrane. Masson's trichrome stain and Pap's silver impregnation were done.
In general the reticular fibers in t h e lamina propria mucosae of the embryo show the transitional form to the structure of the 'adult. The cytoplasmic processes of the basal cells of the epithelium were not observed. The boundary between the epithelium and the lamina propria mucosae shows an almost straight line, and the reticular fibers in the boundary between the epithelium and the lamina pkopria run parallel or wavy to the basal surface of the epithelium. The penetration of the reticular fibers into the epithelium is not yet observed. With the increase of foetal months, the cytoplasmic processes of the basal cell penetrate into the lamina propria, and the reticular fibers of the lamina propria protrude into the epithelium, and both of these fit together. This structure can be observed imcompletely after the seventh foetal month. The fibers which protrude into the epithelium end blind. In general the development of the papillae and the reticular fibers of the lamina propria in the hard palate is more conspicuous than that in the gingiva. No histological difference is observed in the gingiva of the maxilla and that of the mandibula.
