The fine structure of lamellated nerve endings found in the rat gingiva.

The fine structure of lamellated nerve endings found in the rat gingiva (Sprague Dowly) was examined by electron microscopy. The lamellar corpuscles are localized in the subepithelial portion of the dermal papillae and are circular or oval in shape. The lamellar cells surrounding the nerve terminals demonstrate several modifications in their configuration due to the variable number of cytoplasmic sheets. All the sheets are characterized by the presence of numerous caveolae, small mitochondria, a few cisterns of rough endoplasmic reticulum, microfilaments and microtubules. Serial sections clearly showed that the nerve terminal is subdivided into two or four branches, each of which terminates at different levels of the corpuscle. The laminae branch several times, ultimately connecting with those of neighboring laminae through desmosomes, and are separated from similar processes by an interlaminar substance. The nerve endings contain many mitochondria, neurotubules and small clear vesicles. Cytoplasmic protrusions extend from the nerve terminal into the clefts between the lamellar cells. Small clear vesicles are found in the basal area of the protrusion. The interlaminar spaces are occupied by an amorphous material though collagenous fibrils are conspicuous in some regions.