Glandular changes associated with the spontaneous interstitial cell tumor of the rat testes

Testes of untreated F344 and Wistar rats in the control groups of carcinogenicity studies were histologically examined, and the histopathological characteristics and histogenesis of glandular changes in these testes were studied. In 266 testes of 2-year-old F344 rats, 263 had interstitial cell tumors (ICTs) (98.9%) and 39 had glandular changes (14.7%). These glandular changes were also found in 1 out of 38 1-year-old F344 rat testes (2.6%), and 3 in 154 2-year-old Wistar rat testes (1.9%). The changes were observed exclusively in the interstitial cell tumors (ICTs). These glandular changes showed variation in size, shape and number. They were composed of tubules or cysts lined by a layer of cuboidal or columnar epithelial cells, which had terminal bars, occasionally PAS- and alcian blue-positive brush borders, and rarely, alcian blue-positive cytoplasmic vacuoles. Serial sections revealed that the changes were not connected with the rete testes, but with the degenerative seminiferous tubules involved in the ICTs lined by a layer of flat endothelial-like cells. The findings suggest that the lesions constitute metaplastic changes of the Sertoli cells.