Abstract
The perineurium constitutes the basis for the regulation of endoneurial fluid homeostasis. In the work presented here, cytokeratin 18, as an immunohistochemical marker for epithelial cells, was used to identify the perineurium in the peripheral nerves of two species. Two organs, rich in peripheral nerves, were used; the tongue of the bull and the ductus deferens of the male goat. Special attention was paid to one of the the nerve sheath cells - the perineurial cells of myelinated nerves in the skeletal muscle of the tongue and in the smooth muscle in the wall of the ductus deferens. A positive reaction to cytokeratin 18 was found in the perineurial cells of the perineurial sheath in the nerves of various sizes. No difference in the reactivity was observed between the peripheral nerves of the tongue and that of the ductus deferens.