Experimental “Constant Oestrus” and the Notion of Anti-Gonadotropic Hormones. ∗

Abstract

Summary

Parabiotic twins of rats exchange daily about 150 cc. of blood. If one member of a female pair is hypophysectomized it exhibits deficiencies which prove that blood received from the normal mate carries not enough hormones to maintain body weight, thyroids, adrenals and ovaries at normal levels. Castration or sterilization of males and females increases the output of follicle-stimulating hormones to the extent that normal or hypophysectomized twin females go into a condition of constant oestrus. The ovaries are visibly overstimulated and contain large follicles but no corpora lutea. Uterus and vagina exhibit also the characteristics of a maximal or even an exaggerated oestrus condition, indicating the release of large amounts of oestrin by the ovaries. Not enough oestrin accumulates in the castrate member to prevent complete atrophy of the secondary sex characters. This indicates rapid disappearance even of high amounts of oestrin from the circulation. Constant oestrus with a moderate degree of ovarian and vaginal stimulation and almost dioestral size of the uterus is observed in females with experimentally masculinized hypophyses. Both types of constant oestrus can persist indefinitely, at any rate over a full year, without loss of sensitivity by either ovaries or genital accessory organs. It is concluded that no specific anti-hormones are formed, though the hypophysis, probably through the intermediary of the thyroid (and adrenals?) checks the excessive growth of overstimulated ovaries. The loss of reactivity in ovaries after prolonged stimulation with gonadotropic hormones of heterogeneous origin is considered as an immunity reaction to foreign proteins.