On the histology of ductulus lacrimalis in adult, especially on its innervation.

Abstract

The vertical duct of the ductulus lacrimalis has a non-cornificated flattened stratified epithelium like the margo palpebralis, which is, however, about twice as thick as the epithelium of the latter. The subepithelial fibrous tissue shows for the epithelium scarcely formation of papillae. This fact indicates that this mucous membrane is not so favoured with sensory nerve fibres. The transversal duct of the ductulus shows in the lamina propria the formation of lymphatic tissue, especially near the opening into the lacrimal sac remarkably. Next, the changingg of. the epithelium is noticeable. That is in the stratified flattened epithelium appears the stratified columnal epithelium sporadically. Besides, near the lacrimal sac we can find the remarkably thin columnal epithelium represented by only 2 or 3 layers of epithelial cells, being penetrated by many of lymphocytes. Thirdly comes the bud- or fungi-formed thickning of the mucous membrane strongly projecting into the lumen of-the duct, filled with the well-developed lymphatic tissue and having the epithelium of thin stratified columnal nature. This formation might be thought to exist in order to let the lymphocytes display their duty in full to catch the harmful objects. The weak nerve plexus in tela submucosa is composed of many medullary sensory and a few non-medullated vegetative fibres. The latter finally become to the terminalreticulum and distribute widely in the subepithelial tissue, while the former terminate mainly in lamina propria with various terminations, which are divided roughly into the unspecific or non-contorted and the specific or contorted terminations. The sensory fibres of the non-contorted terminations are mostly composed of medium thick fibres, but rarely of strong fibres, show in general the equality of thickness and terminate sharply or dully direct beneath the epithelium or in direct contact with the basis of the epithelium. The terminations are according to their complexity subdivided into the unbranched and the branched terminations, furthermore the latter into the simple and the complicated forms. The contorted terminations. are seen only in ductulus lacrimalis and margo palpebralis (Seto).9) Their sensory fibres are mostly strong medullated fibres, being often accompanied by small medullated fibres, represent scarcely the variety of thickness and pass into irregular looping terminal formations containing special nuclei here and there. The terminations are further divided into the simple and the complicated forms according to their scale. The former are mostly found in the vertical duct, the latter chiefly in the transversal duct. Some of the specific terminations are represented as the simple glomerular formations, though a few. Besides, as a kind of the specific terminations sometimes exist the unformed terminations composed of strong fibres rich in variety of thickness and showing not so evident winding course, too.