Priming procedure and cell isolation for study on luteal cell response to peptide hormone in the rat

The objective of this study was to develop a method of isolating luteal cells from the ovaries of immature rats pretreated with pregnant mare serum gonadotrophin (PMSG). After the ovaries were digested by collagenase and trypsin, the corpora lutea were obtained from the tissues, gently pressed in a test tube, and then placed on a sucrose density gradient. The two bands that appeared in the tube after centrifugation were designated S1 (top band) and S2 (bottom band). Progesterone and 20 alpha-dihydroprogesterone (20 alpha-DHP) secreted by the isolated cells during short-term incubation were measured by radioimmunoassay (RIA). A larger amount of progesterone, i.e., 60 to 260 ng/10(5) cells, was secreted by S1 cells than by S2 cells during the 18-h incubation. These results suggest that this simple procedure for isolation of luteal cells may provide a suitable model for in vitro studies of the luteal function.