Endocrinology of ovarian tumor formation in parabiotic rats.

The method of parabiosis in rats was used in the analysis of the effects produced by continuous gonadotrophic overstimulation of ovaries. The source of constant gonadotrophin supply was the hypophysis of the castrate member of pairs. The reactor animal was either a hypophysectomized female (I), a male carrying an ovarian graft (II), or a constant-estrus female (III). The essential feature in each of the three combinations was the subjecting of ovaries to constant stimulation by"cas t ra te gonadotrophins" without interruption of reactions by ovulation and corpora lutea formation. In all three combinations the follicular granulosa of many, sometimes of all, mature follicles developed granulosa-cell tumors. These tumors produce and release estrogenic hormones in considerable quantity, as evidenced by enlargement of the hypophyses and adrenals (combinations I I and II I ) and atrophy of seminal tubules (combination II). Various aspects of theca and interstitial-cell luteinization are also considered; they support the contention that the "castrate hormone" contains the interstitial-cell-stimulating as well as the follicle-stimulating factor of hypophyseal gonadotrophins. The possibility that failure to ovulate 'and to form corpora lutea is not due to absence of a special gonadotrophin, but is a consequence of uninterrupted stimulation at constant levels, is admitted. The bearing of these experiments on the interpretation of several clinical pathologies and their etiologies is discussed.