The structure of the interstitial surfaces of the epithelial basement membranes of mouse oral mucosa, gingiva and tongue

It is known that the gaps between epithelium and the underlying connective tissue usually occur between the epithelial cells and the basement membrane, resulting in exposure of the cellular surface of the lamina densa. After dithiothreitol separation, the epithelia of oral mucosa, gingiva, and tongue were mechanically peeled off from the underlying connective tissues. This treatment severed the connections between the basement membrane and the underlying connective tissue and the anchoring fibrils were pulled off from the collagen layer. In contrast, connections between the epithelial cells and basement membrane were preserved, resulting in exposure of the interstitial surfaces of the laminae densae. Scanning electron-microscopic observations of those interstitial surfaces were possible using the specimens prepared as above. The basement membranes of these three oral epithelia were morphologically the same not only by transmission but also by scanning electron microscopy. Scanning electron-microscopic observations revealed that their laminae densae were composed of fine fibrils and demonstrated three-dimensionally the projection of the anchoring fibrils from the laminae densae to the interstitial side. These findings coincide with those for epidermal basement membrane, which had already been observed with the same method.