Differential Responsiveness of A and G3H Mouse Mammary Tissues to Somatotropin-Containing Hormone Combinations. ∗

Abstract

Summary and Conclusions

Mammary tissues from A/Crgl and C3H/Crgl strains of mice were transplanted into mammary gland-free fat pads of female hybrids (C3H × A, AX C3H). The hosts were hypophysectomized-ovariectomized, and treated with estradiol + progesterone + somatotropin for 21 days. Half of them received an additional 5 days treatment with Cortisol + somatotropin. On the basis of the lobuloalveolar mammogenic and lactogenic responsiveness of the A, C3H, and hybrid mammary tissues to the hormone combinations used, the following general conclusions were drawn: 1. There is a quantitative difference in lobuloalveolar mammogenic response of A/Crgl and C3H/Crgl mammary tissues to the somatotropin-containing hormone combination, degree of response being greater in the C3H/Crgl mammary gland. 2. There appears to be a qualitative difference in lactogenic response of A and C3H mammary tissue to the somatotropin-containing combination. 3. The occurrence of milk secretion in mammary glands of hybrids (A × C3H, C3H × A) and in C3H mammary transplants, and its absence from A transplants, indicate that the genetic determinant for mammary gland sensitivity to the somatotropin-containing hormone combination must lie in the mammary tissue itself, and that this can be transmitted by either male or female C3H parent to the hybrid offspring.