Failure of luteinizing hormone-releasing hormone (LHRH) to affect the differentiation of LH cells in the rat hypophysial primordium in serum-free culture.

The aims of this study were to investigate the differentiating capacity of adenohypophysial LH cells in a serum-free culture medium and to test whether cytogenesis is affected by synthetic LHRH. The adenohypophysial primordia of fetal rats were isolated on days 11.5 and 12.5 of gestation and cultured without serum for 10 and 9 days, respectively, in synthetic Medium 199 or alpha MEM. Immunohistochemical examination using the PAP method revealed that most culture explants, apart from a few degenerate ones, contained LH cells. In comparison with Medium 199, which has been widely used as a culture medium for hypophysial explants, alpha MEM gave far better results and the primordia cultured in this medium showed better tissue growth and contained a greater number of LH cells. Administration of synthetic LHRH (10 ng/ml) on the first day of culturing had no effect on the number of LH cells, no matter whether or not the culture medium was supplemented with insulin, transferrin or thyroxine. These results suggest that at the early developmental stage LHRH is not essential for the differentiation and/or proliferation of LH cells.