A Comparison of the X-Zone of the Adrenal Cortex in Two Inbred Strains of Mice*

Recent work by Woolley, Fekete, and Little (6, 8) has demonstrated that in certain inbred strains of mice striking changes in the adrenal cortex follow early castration. The female mice of the dilute brown (Dba) strain, castrated at birth, showed areas of nodular hyperplasia in the adrenal cortex, after one year involving and partly replacing all three zones of the cortex. These mice also showed marked development of the mammary glands. It was suggested that the action of the hyperplastic adrenals stimulated the development of the mammary glands. It was further shown that the adrenal hyperplasia occurred in two strains of mice with a high incidence of spontaneous mammary tumors (Dba and C 3 H ) and was absent in the C57 black strain which has an exceedingly low incidence of spontaneous mammary carcinoma. The differences between the castrated females of the Dba and C57 strains suggested the possibility that differences might be detected in the adrenals of intact females of the two strains. A comparison of the adrenal glands of two strains of mice varying in their incidence of mammary tumor has been made by Cramer and Horn ing (2). They attempted to demonstrate a relation between "brown degeneration" of the adrenal gland and the appearance of mammary tumors. This brown degeneration consisted of necrotic tissue in the peripheral part of the medulla. Recently Blaisdell, Gardner, and Strong ( i ) have investigated the problem. They concluded after a study of i i different strains of mice that there was no consistent relation between frequency of brown degeneration and the potentiality of any strain to develop mammary cancer. While studying the early stages of adrenal changes following castration, we noted a histological difference between a high tumor strain and a low tumor strain. The appearance and persistence of the x-zone of the adrenal in one strain of mice differed from those of the other strain.