Comparative ultrastructural study of normal, adenomatous, carcinomatous, and hyperplastic cells of canine hepatoid circumanal gland

Transmission electron and light microscopy studies were carried out on morphologic characteristics of cellular organelles of normal and different neoplastic cells of hepatoid circumanal glands of 16 dogs. The ultrastructural features of the reserve and transitional cells in the adenomas and carcinomas are highly suggestive of different carcinogenic stimuli for each form of hepatoid circumanal gland neoplasm. The reserve cells, in response to the carcinogenic stimuli, appear to be growing at the expense of the degenerating glandular cells.