Electron microscopic studies on human tracheal glands (author's transl)

Abstract

An electron microscopic study on fine structure of the human tracheal glands, on which few reports have been published, was carried out.The materials were obtained duing surgical procedures of the larynx and trachea.The human tracheal gland mainly locates in submucosa of the trachea.The shape of gland is simple or compound tubulo-alveolar, and the gland has a duct and a secretory portion(acinus).The secretory portion of the gland comprise of mucous cells and serous cells consistently in a regular arrangement.The mucous cells adjoin directly distal to the branched duct and followed by serous cells.Serous cells form frequently a deanilune.The secretory portion of the gland is surrounded by myoepithelial cell sresembling smooth musclefiber, and they are encased further by metnbrana propria comprised of a basement membrane and connective tissue.The duct of the tracheal gland has double layers of epithelial cells, viz.tall columnar cells facing the lumen and basal cells outside.The tall columnar cell frequently contains round granules suggestive of anactive secretory function.In our observation ultrastructural characteristics of the unicous cells and of the serous cells are investigated separately, and the mechanism of secretion is morphologically elucidated through the electron microscopic investigation of their morphological changes corresponding to the secretory cycle.No appreciable morphological difference exists between the serous cells constituting serous tubules and demilune.Mitochondria-rich cells(oncocytes)are occasionally found within the epithelium of the secretory portion and in a rare instance they contained secretory granules.Several findings on myoepithelial cells resembling smooth muscle fiber which are found in a considerable number at the base of the glandular cells of the secretory portion are described.