Fine Structure of the Normal Canine Prostate

The secretory epithelia of prostate glands of healthy dogs have varieties of organization and subcellular structure that previously have not been reported. In some acini, the secretory cells are columnar, and are aligned in a single layer (Fig. 1). The cells are of two types, “light” and “dark”, which I have been able to distinguish only on the basis of general cytoplasmic density. Other structural features of interest are: extensive lateral intercellular interdigitation; irregularly shaped, large lipid bodies, often associated with high concentrations of glycogen, and present in both the apical and basal regions of the cells; apically concentrated secretory granules, some of which are distinguished by having dense cores; prominent Golgi apparatuses, oriented both apically and laterally; extensive rough endoplasmic reticulum, some cisternae of which are distended; and nuclei which are often observed to be multi-lobular and very irregular in outline. Cells arranged in this manner have well defined tight junction complexes at their lateral apical surfaces.In most acini, however, the architecture is more complicated. Often, thin extensions of dark cell cytoplasm surround and separate adjacent light cells (Fig. 2). The dark cell cytoplasm is expanded in some areas to accomodate mitochondria, and it contains numerous ribosomal clusters and rough endoplasmic reticular cisternae. Desmosomal attachments between the light and dark cells are found commonly in the regions of envelopment. I have not yet determined whether the dark cells completely encapsulate the dark cells in three dimensions.