Ultrastructure of the apocrine‐sebaceous anal scent gland of the woodchuck, Marmota monax: Evidence for apocrine and merocrine secretion by a single cell type

Abstract

AbstractLight and electron microscope studies of the woodchuck anal scent gland revealed that it is composed of apocrine and sebaceous components emptying into a common duct. In the apocrine acini, the single secretory cell type showed evidence of both merocrine and apocrine secretion. Merocrine secretion resulted in the release of the contents of apical secretory granules while apocrine secretion released apical caps of cytoplasm by a process involving the following: (1) formation of an apical cap, usually containing no organelles or secretory granules; (2) appearance of a single row of flattened vesicles forming an incomplete barrier between the apical cap and the remaining cell cytoplasm; and (3) fusion between vesicles and plasmalemma, causing progressive constriction of the neck of the apical cap and eventual cap release. Since both merocrine and apocrine secretory processes have been reported in three other types of apocrine glands, it is likely that the occurrence of both processes in a single cell is a general characteristic of apocrine cells.Several features apparently unique to these particular apocrine cells were observed, including secretory granules of a single morphological type and a population of small dense‐cored basal vesicles of unknown function. Therefore, it would appear that, just as with merocrine cells, apocrine cells from different types of glands also have distinctive morphologies which probably reflect real differences in their functions and products.