Toxic Effects of Steroid Hormones on Organ Cultures of Mouse Mammary Tumors, With a Comment on the Occurrence of Viral Inclusion Bodies2

Abstract
Several steroid hormones used in studies of mammary tissue development in organ culture were examined for their effects on spontaneous mammary tumors. Mammary adenocarcinomas from C3H/Crgl mice were cultured for 5 days in medium 199 supplemented with the following steroids in concentrations ranging from 0.02 to 200 [mu]g per ml estrone, estradiol-17[beta], progesterone, cortisol, corticoster-one, aldosterone, and deoxycorticosterone. All steroids were toxic at the higher dose levels. The responses to the several steroids were compared, and the minimum toxic doses determined. Progesterone was the most toxic of the steroids used, but its toxicity could be prevented, to some extent, by addition of serum to the medium. The occurrence of cytoplasmic inclusions, representing accumulations of virus-like particles, was also noted as a result of organ culture of these tumors, with and without hormone supplementation of the medium. No consistent effect of the steroids on the occurrence of inclusions, or on the histology of the explanted tumors, was noted.