Dependent and autonomous mammotropic pituitary tumors in rats; their somatotropic features.

Abstract

Pituitary tumors induced in the rat by sustained hyperestrogenization are dependent neoplasms in that, when transplanted, they will grow only in estrogen-treated hosts. Upon subpassage, these dependent tumors give rise to autonomous variants. These tumors are markedly mammotropic and somatotropic. Evidence is presented to suggest that this is not due to an admixture of two types of cells or to two different hormones but is an inherent characteristic of one hormone secreted by mammotropes. Nephrosis, as yet unexplained, is a common secondary change in animals bearing such tumors. Hyperestogenization is the common mechanism by which three procedures (irradiation, castration, and administration of estrogens) will induce mammotropic pituitary tumors.