Studies on DNA synthesis in goat mammary organ culture under the influence of various hormones.

A study has been made of the hormones required for stimulation of DNA synthesis in organ culture of mammary tissue of goats. On culture in Waymouth's medium without added hormones the incorporation of 6-3H-thymidine into DNA was low. The addition of insulin caused a high stimulation of thymidine incorporation. However, the addition of cortisol, prolactin, growth hormone, 17beta-estradiol, progesterone alone or in combination had no effect on DNA synthesis. The minimal effective concentration of insulin was 0.1 mug ml-1. The addition of calf serum caused slight stimulation of DNA synthesis. When the mammary explants were exposed to a combination of serum and insulin, the rate of thymidine incorporation was always additive suggesting that DNA synthesis was affected independently by serum and insulin.