Lactating goat mammary gland cells in culture.

1. Isolated mammary gland cells were cultured embedded in collagen gels or as monolayers on floating collagen gels. Under these conditions the cells were able to grow for at least 6 weeks during five passages. Growth was sustained in M199/F12 (1:1) supplemented with insulin, hydrocortisone, epidermal growth factor, tri-iodothyronine, estradiol and bovine serum albumin. 2. The cells secreted lactose into the medium in significant amounts throughout the culture period. 3. Prolactin had a slightly stimulatory effect as had fetal bovine serum on growth and protein synthesis, but none of these factors were obligatory in this respect. Insulin-like growth factor I (Somatomedin C) could replace high concentrations of insulin whereas bovine growth hormone had no detectable effect. 4. Depending on the hormone content of the medium and the age of the culture, different labelling patterns of the arachidonic acid-containing phospholipids were observed. The effect of prolactin on phosphatidyl inositol and arachidonic acid metabolism was studied.