Fibrillar bodies in human prostate

Electron microscopy was used in an attempt to understand the initial but still obscure steps in the formation of corpora amylacea. To that effect, a specimen of hyperplastic prostate, selected by light microscopy for its abundance in corpora, was examined in the electron microscope. Hitherto unreported, small fibrillar bodies surrounded by glycogen granules were observed free or bound to the surface of acinar cells of the specimen. Fibrils of these bodies were different from amyloid fibrils of corpora. They were thinner, more electron dense, and branching. While the bodies were easily detected in semithin sections of the specimen, as well as in those of two other hyperplastic prostates, they were not seen in sections of their paraffin-embedded counterparts. Neither were the bodies seen in histological preparations of 18 other prostate specimens (8 hyperplasias, 10 cancers). Whether the fibrillar bodies were precursors of corpora could not be demonstrated.