Fatty acid synthesis by explant cultures from the mammary glands of goats on days 60 and 120 of pregnancy

ABSTRACT Explants of mammary glands from 60-day pregnant goats showed a mean fourfold increase in fatty acid synthesis from acetate when cultured with insulin+ cortisol. Epithelial cells increased their area by 60% but no secretory activity was induced. In 120-day pregnant goats, fatty acid synthesis and epithelial cell area were greater than at day 60 of pregnancy and were unaffected by hypophysectomy or by daily treatment with bromocriptine from day 60. Neither increased further on culture of mammary explants in insulin + cortisol. Ovine prolactin increased fatty acid synthesis two-fold when added to insulin + cortisol in cultures of mammary tissue from goats on day 60 of pregnancy and secretory activity was induced. On day 120 of pregnancy insulin + cortisol + prolactin sustained or slightly stimulated both fatty acid synthesis and the extensive secretion present in the tissue at the start of culture. Synthesis of medium-chain fatty acids of milk-fat was also sustained by prolactin in one goat. An atmosphere of air was found to maintain normal histological structure of the mammary gland. By contrast, in 95% oxygen, explants from goats which were 60 days pregnant showed epithelial cells filling the lumina of ducts and alveoli in 60% of explants and a poor response to prolactin. J. Endocr. (1984) 100, 87–92