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The perineurial cells of the sciatic nerve of mature albino rats were investigated by using light microscope (LM), transmission electron microscope (TEM) and scanning electron microscope (SEM). The perineurium of the sciatic nerve was composed of several lamellae of thin perineurial cells which were held together by the zonula occludens and also by the zonula adherens. The TEM view of the perineurium revealed that the plasmalemma of the perineurial cells presented numerous caveolae similar to those described in the endothelial cells of blood capillaries. By SEM, the perineurial cells were very thin, flattened out with various shapes from rectangular to hexagonal, and arranged closely to each other in the fashion of a stone pavement around the nerve fascicles. It was possible to isolate the perineurium from the nerve and to demonstrate the cellular border of the perineurial cell by silver impregnation method. The SEM observation of the perineurial cells ascertained the figure of the cells which were seen in the silver-impregnated specimen under LM. The present authors have interest in the fact that shape and arrangement of the perineurial cells of spinal nerves resemble closely those of the myoid cells in the limiting lamina of the seminiferous tubules of the mammalian testes. The meaning and significance of the similarity between these two types of cells was discussed.

with special attention to intraepithelial nerve supply , the distribution of peripheral nerve fibers in the ejaculatory duct of the monkey (Macacus fuscatus) was examined by histochemical and immunohistochemical methods and conventional transmission electron microscopic (TEM) method. The conventional TEM study has suggested that there are two types of intraepithelial nerve fibers, i. e. cholinergic and peptidergic. Acetylcholinesterase (AChE)-positive nerve fibers which were seen by means of light microscopy (LM) as surrounding the epithelium were revealed to be present intraepithelially by means of TEM examination. Neuropeptide Y (NPY)-like immunoreactive nerve fibers were richly distributed in the ejaculatory duct with a dense plexus spreading just beneath the epithelium. The immunoreactive nerves appeared, in part, to enter the epithelium. Substance P (SP)-and calcitonin gene-related peptide (CGRP)-like immunoreactive nerve fibers were found to be present to a moderate extent in the ejaculatory duct; some of them entered the interior of the epithelium to extend their nerve terminals to its free surface. Neural elements clearly immunoreactive for tyrosine hydroxylase (TH) and vasoactive intestinal peptide (VIP) could not be found in the ejaculatory duct, except for the surroundings of the blood vessels. Possible functional roles of these intraepithelial nerves were discussed on the basis of their distribution pattern.

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