Incipient spontaneous granulosa cell tumour in the gerbil, Meriones unguiculatus.

In 167 cases of granulosa cell tumour (GCT) in the gerbil, Meriones unguiculatus, 42.5% (71 cases) were in the ovaries, with no evidence of macroscopic lesion. In this paper, we describe the common findings in the incipient--microscopic--type of this spontaneous ovarian tumour occurring in gerbils younger than two years of age.