Extrinsic nerve supply of the naked rhinarium in the tree shrew.

The extrinsic nerve supply of the median strip of skin in the naked rhinarium of the tree shrews (Tupaia glis) was studied by means of nerve section. Experiments were designed, where the external nasal nerves, infraorbital nerves or a combination of both were sectioned. The cholinesterase and silver impregnation techniques were employed to demonstrate intraepithelial nerves, mammalian end-organs, and the dermal nerve plexus before and after denervation. These experiments have given results contrary to what was expected, as the skin in this region, which develops from the frontonasal process, was found to be supplied by the infraorbital nerves (branches of the maxillary division of the fifth cranial nerve, which is the nerve of the maxillary process) and not the external nasal nerves (branches of the ophthalmic division of the fifth cranial nerve, the nerve of the frontonasal process).