ULTRASTRUCTURE OF THE PAROTID-GLAND IN THE COMMON VAMPIRE BAT, DESMODUS-ROTUNDUS, WITH SPECIAL EMPHASIS ON ONCOCYTES

The parotid gland of the common vampire bat, Desmodus rotundus, is a p ure seromucous gland. Typical acinar cells have a complement of secret ory granules with a light matrix and one or several spherules and anci llary densities. These cells also contain mitochondria of conventional appearance. Mixed in with these acinar cells are cells that fulfil al l of the ultrastructural criteria for identification as oncocytes. The y contain enhanced numbers of mitochondria that frequently display pec uliarities in the number and disposition of their cristae. The oncocyt e mitochondria are closely packed and often are joined by periodic bri dges. Most of the cells in the intercalated ducts are cytologically un remarkable; a few scattered duct cells have a single, grossly distende d cisterna of rough endoplasmic reticulum that contains a homogeneous material of moderate density. The intercalated ducts are succeeded by ducts that lack the usual basal striations, but that consist of cells with numerous, small, dense granules. These secretory ducts probably a re the homologues of striated ducts in parotid glands of other species . The structure of these ducts in the parotid gland in the vampire bat suggests that this gland does not play a homeostatic role in the regu lation of electrolytes, a role that appears to be carried out in this bat in the submandibular glands, but that its major intralobular ducts contribute substantial quantities of organic material to the saliva.