INFLUENCE OF HORMONES ON LOBULO-ALVEOLAR DIFFERENTIATION OF MOUSE MAMMARY GLANDS IN VITRO

Abstract

SUMMARY (1) To induce mammary differentiation in vitro, BALB/cCrgl mice were given hormones before incubation of their mammary glands in defined medium containing steroid hormones (oestradiol, progesterone and aldosterone), anterior pituitary hormones (prolactin and growth hormone), and insulin. The sequence of lobule development in vitro obtained in this way was determined by cultivation of tissues for 1, 2, 3, 4 and 5 days. Lobules appeared on the 3rd day of culture, although proliferation occurred throughout the 5-day period. (2) In two other sets of experiments, mammary glands were exposed to various combinations of hormones in culture. Survival of cultured tissues required the presence of insulin, whereas differentiation required the presence of steroid hormones, anterior pituitary hormones, and insulin. Of the steroid hormones used, aldosterone alone fulfilled the minimum steroid hormone requirement for lobule formation in vitro.