Serum-free Medium Conditions for Steroidogenesis of Bovine Follicular Thecal Cells Cultured on Collagen Gel Matrix

Thecal cells isolated from bovine ovarian follicles were cultured with a serum-free basal medium or a serum-free complete medium in the presence or absence of collagen gel matrix, and their cellular proliferation and steroidogenesis were compared with those of cells cultured with a serum-containing medium. The cells cultured with the serum-free basal medium produced larger amounts of progesterone, androstenedione, and estradiol than the cells cultured with the serum-containing medium, but no appreciable cell proliferation was observed in the serum-free medium. Response of thecal cells to 8 bromo-cAMP, a steroidogenic agent, varied according to the type of steroid production examined and the type of culture medium used. In a cultivation period of 4 d, progesterone production was stimulated about five-fold by 8 bromo-cAMP in the serum-free complete medium on collagen gel matrix and in the serum-free basal medium without collagen matrix, whereas androstenedione production was stimulated about three- to fourfold in the serum-free complete medium on collagen gel matrix and in the serum-free basal medium with or without collagen matrix. Estradiol production, however, was significantly suppressed by 8 bromo-cAMP in the serum-free complete medium on collagen gel matrix and also in the serum-containing medium. Thus, among the conditions examined, the most suitable primary culture media for steroidogenesis of thecal cells were the serum-free media, especially serum-free complete medium on collagen gel matrix.