Benign testicular hyperplasia in Mongolian gerbils (Meriones unguiculatus).

At necropy, 20 out of 35 Mongolian gerbils (Meriones unguiculatus) with prolonged infertility at 12-30 weeks of age were found to have spontaneous hyperplasia in both seminiferous and epididymal tubules. This high incidence of hyperplasia in young gerbils is indication of possible congenital lesions and suggests the possibility of using these animals as a useful model for the further study of male infertility.