The adenomatoid tumor: Fine structural evidence for a mesothelial origin

Abstract

The fine structure of an adenomatoid tumor of the epididymis is described. The thin-walled channels that characterize light microscopic preparations are lined by cells having irregular, microvillus-like projections on their luminal surface. Adjacent cells are united by terminal bars and by elaborate series of desmosomes. Between adjacent cells, there are regions where the apposed cell membranes separate to form an anastomosing network of secondary channels which communicates with the main channel lumen and rarely with the stromal space. Round cells present within the channel lumens do not closely resemble any specific blood or connective tissue cell. It is suggested that these cells migrate from the surrounding stroma into the channel lumen where in time they disintegrate. The fine structural observations strongly support the concept of a mesothelial origin of the adenomatoid tumor.