Innervation of the hard palate in cat and hedgehog.

Abstract

The fine structure of the hard palates of the cat and the hedgehog is also similar to that in man, but in development the former is far in arrear to the latter, especially in the thickness of the epithelium and the size of the papillae in the mucous membrane. Consequently, the development of the sensory terminations formed in the papillae and of the intraepithelial fibres ending in the epithelium stands also in a much lower stage in these mammals than in man. The histological picture of the hard palate of the hedgehog showing a somewhat lower development than that of the cat, the development of the sensory nerve terminations is also to some extent poorer in hedgehog. The sensory terminations in the hard palate in cat are chiefly formed in the major papillae, and mostly represented by very simple unbranched terminations. The intraepithelial fibres are also formed by sensory fibres penetrating into the epithelium from the large papillae, and also end mostly in simple unbranched terminations. These fibres are composed of unmedullated smooth-surfaced, uniformly thin fibres, run through or between epithelial cells and end sharply or with small nodes near the surface layer of the epithelium. In the hard palate in hedgehog, the sensory terminations in the papillae as well as the intraepithelial fibres are all similar in formation and nature to those in cat, but are developed somewhat poorer than the latter both in number and in scale. In particular, the intraepithelial fibres here mostly end in the basal or middle layer, without reaching the surface layer, of the epithelium.