Different response of porcine large and small luteal cells to PRL in terms of progesterone and estradiol secretion in vitro.

The extent of progesterone and estradiol secretion by isolated either large or small luteal cells was examined during incubation of separate cell types in medium without and with 100 ng/ml PRL. Small and large luteal cells were isolated from early corpora lutea of pig by means of Ficoll continuous gradient. The amount of progesterone released by large cells into the incubation medium was 5 fold higher than that by the small ones. In the presence of PRL large cells secreted more progesterone (1.5 fold) than the control ones. We did not observe any stimulatory effect of prolactin on progesterone secretion by small luteal cells. On the other hand, prolactin added to the medium decreased estradiol production by both cell types.