Sensory innervation of gingival and alveolar mucosa of the house musk shrew (Suncus murinus).

The lingual gingival and the alveolar mucosa of mandible of the house musk shrew (Suncus murinus) were stained by methylene blue vital staining or osmic acid staining, and mounted as whole thickness preparations. The sensory innervation and the distribution of sensory receptors were investigated with a light microscope. The nerve fibers supplying these regions derive from the sublingual nerve, which ascend in the mucosa as they branch out. Sensory receptors found in the present study are of four kinds; free nerve endings, bush-like nerve endings, Merkel cell-neurite complexes and encapsulated corpuscles. The Merkel cell-neurite complexes were scarce and localized in the upper margin of gingival mucosa. The bush-like nerve endings were distributed preferentially in the alveolar mucosa, in which their maximum density was 9-23 per mm2. Among the organized receptors, the encapsulated corpuscles appeared most frequently throughout the mucosal area investigated, and their maximum density amounted to 27-56 per mm2 in the gingival mucosa. These corpuscles were relatively small and poorly differentiated. Although the bush-like nerve endings and the encapsulated corpuscles were fewer in the third molar region, there was no obvious regional difference in their distribution densities from the premolar region to the second molar region.