Quantitative changes in the morphology of the aging canine prostate.

Stereological methods at the light and electron microscopic levels were used to examine the morphological changes in the beagle prostate associated with increasing age and with the occurrence of spontaneous benign hyperplasia. Analyses of semithin sections of tissue embedded in plastic revealed that proliferation of prostatic glandular and stromal components, increase in epithelial cell numbers, and increase in epithelial cell size all contributed to the dramatic increase in prostate weight seen in aging dogs. Analyses at the electron microscopic level revealed that the volume densities of rough endoplasmic reticulum and secretion granules were significantly lower in epithelial cells of the immature prostate than in the prostate of mature dogs (greater than 1.5 years of age). In contrast, no significant differences were seen in the volume densities of rough endoplasmic reticulum, free ribosomes, secretion granules, smooth endoplasmic reticulum, or mitochondria in randomly selected prostatic epithelial cells of dogs 1.5 to 9 years of age, whether or not the prostates were hyperplastic.