Spontaneous pinealoma in a male Crj : CD (SD) IGS rat

A pinealoma (benign) was found in a 61-week-old male Crj:CD (SD) IGS rat. T he neoplasm was located between the cerebral hemispheres and the cerebellum . Histologically, the tumor cells consisted of two cell types: large, pale- staining cells and small dark-staining cells. A fibrovascular stroma divide d the tumor cells into incomplete lobules or nest structures. Relatively nu merous mitoses were noted in the tumor cells. Ultrastructurally, the tumor cells contained dense-cored vesicles, approximately 120 nm in diameter.