INNERVATION OF CUTANEOUS STRUCTURES IN THE MOUSE HIND PAW - A CONFOCAL MICROSCOPY IMMUNOHISTOCHEMICAL STUDY

The normal innervation of structures in mouse foot pads was investigat ed with immunohistochemistry and confocal microscopy, Nerves were visu alized by incubating Zamboni fixed, thick, frozen sections with antibo dies to protein gene product 9.5 (PGP 9.5), vasoactive intestinal pept ide, substance P, calcitonin gene-related peptide, and protein zero, T he antibodies were localized using cyanine 3.18 labeled anti-rabbit ga mma globulin, PGP 9.5 immunolocalization showed dense nerve bundles at the base of the foot pad with branches to larger blood vessels, sweat glands and epidermis. Sweat gland tubules were surrounded by numerous sudomotor axons; single fibers accompanied the sweat duct toward the skin's surface, Nerve bundles containing myelinated and unmyelinated a xons ran through and around the centrally located sweat gland cluster to end in free nerve endings and Meissner's-like corpuscles at the ape x of the foot pad, Other bundles running parallel to the epidermis gav e arcuate branches that supplied epidermis on the sides of the pads wi th a rich nerve network, principally with free nerve endings that ofte n reached the most superficial cell layers of epidermis, Calcitonin ge ne-related peptide-immunoreactive (-ir) nerves were distributed to der mis and epidermis in lower density than PGP 9.5-ir fibers, Substance P -ir fibers were less numerous; most terminated as free endings in deep er layers of epidermis, Vasoactive intestinal peptide-ir nerves almost exclusively innervated sweat glands, ducts and blood vessels, but not epidermis. The mouse hind paw has potential to serve as a model syste m for investigations of functional and morphological changes that affe ct peripheral and autonomic nerves under diverse experimental conditio ns. (C) 1995 Wiley-Liss, Inc.