Response to gonadotropic stimulation of cultured rat luteal cells isolated from corpora lutea of early pregnancy. Cytochemical and biochemical studies.

The hormonal activity of corpora lutea isolated from pregnant rat was examined on 1, 2, 3, 4, 5, 6, 15, and 20th day of pregnancy. The cells were grown as a monolayers up to 6 days at 37 degrees C in Medium 199 supplemented with 10% calf serum. The concentrations of progesterone and estrogens were measured using appropriate radioimmunoassays [1, 7] respectively. Luteal cells were cultured with the addition of the following amounts of hormones: 100 ng LH, 10 i.u. HCG, 100 ng PRL and 150 ng estradiol 17 beta. Cytochemical and histochemical observation of the activity of delta 5, 3 beta-hydroxysteroid dehydrogenase (delta 5, 3 beta-HSD) were also carried out. The addition of LH and HCG to culture medium of cells collected on day 1 and 2 of pregnancy caused increased histochemical reaction for delta 5, 3 beta-HSD and progesterone secretion. It was only on day 3 of pregnancy that the influence of PRL was observed. On day 4 corpus luteum cells began to respond to exogenous estradiol. On day 5 the sensitivity of corpus luteum to exogenous hormones disappeared but the intensive hormonal activity of the corpus luteum marked by the high level of progesterone, was maintained.