Abstract
To examine the distribution of autonomic nerves in the human arrector pili muscle, we treated the human scalp with trypsin-HCl method by Uehara et al., and studied it through a scanning electron microscope. Further, the localizations of S-100 protein and NSE with immunohistochemical technique and an ordinary transmission electron microscope were studied, along with the results used in interpreting the scanning electron micrographs. Under the scanning electron microscope, the arrector pili muscle was composed of bundles of elongated spindle cells 4μ in diameter, and Schwann cell and nerve fibers were observed on its surface. An ampulla was formed at the site of the nucleus of Schwann cell, from which nerve fibers extended to several arrector pili muscle cells. Nerve fibers that branched out from the nerve fiber bundles were distributed over the surface of the muscle cells, and their terminals were swollen spherically. There was no direct contact between the nerve fibers and the arrector pili muscle cells, and no special receptors for the nerve endings were detected on the surface of the muscle cell. The above findings should be helpful in studying the three-dimensional relationship between the arrector pili muscle and the autonomic nerves.
