Enhancement by Pituitary Isografts of Mammary Hyperplastic Nodules in Adreno-Ovariectomized Mice

Summary

The effect of pituitary isografts on the maintenance and growth of mammary hyperplastic nodules (HN) was studied in adreno-ovariectomized, multiparous, female C3H/He mice, 7–8 months old. Forty days after adreno-ovariectomy and simultaneous isografting of pituitaries under the right kidney capsule, HN averaged 20 and 33 per mouse in the groups receiving grafts of 1.5 and 3 pituitaries, respectively—not significantly different from those of controls (25/mouse). The number of HN in the adreno-ovariectomized controls was 7 per mouse. The average size of HN was larger in the mice with 3 pituitary grafts than in the intact controls. These results show that mammotropic hormones, secreted from the grafted pituitaries, promote the maintenance and growth of mammary HN in the apparent absence of steroid hormones, and thus indicate the primary importance of mammotropic hormones in this process.