In castrated female rats with one ovary in the spleen that received 5 units of luteotrophin intramuscularly, 3 times weekly, a luteoma appeared at 160 days, and one granulosa-cell tumor was found in 175 days. In similarly prepared animals injected intraperitoneally with 5 units of pregnant mares' serum, 3 times weekly, luteomas appeared as early as at 90 and 127 days, and granulosa-cell tumors at 126, 150, and 194 days. Unilaterally castrated female rats with one ovary in the spleen served as controls to each of the above groups, and the exogenous hormones in both cases did not stimulate the intrasplenic ovary.

These findings are evidence that exogenous gonadotrophins may accelerate the development of both luteomas and granulosa-cell tumors in the rat ovary transplanted to the spleen of castrates. This lends credence to the hypothesis that increased or uninhibited pituitary stimulation of the intrasplenic ovary may be an important factor in the development of such tumors in the rat.

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This investigation was supported by the Damon Runyan Memorial Fund for Cancer Research and the generous financial assistance of Mr. Francis Bloch.

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