Identification of relaxins in porcine follicular fluid and in the ovary of the immature sow.

Relaxin was measured by radioimmunoassay in follicular fluid from sows which were of different reproductive states. In non-pregnant animals, follicular fluid relaxin values ranged from 0.23 to 666 ng/ml. For pregnant animals the range was 172.6-32 707 ng/ml and for sows with polycystic ovaries this range was 5.0-2800 ng/ml. For polycystic ovaries only there was a correlation (r = 0.74) between the diameter of the follicle and relaxin concentration in the respective fluid. Gel filtration species of relaxin, of molecular weights 27500, 19000 and 6000. Relaxin was extracted from 1 kg of ovaries collected from prepubertal pigs and gel filtration studies indicated the presence of large molecular weight species in addition to a molecule of approximately 6000. These experiments suggest that the corpus luteum is not the sole source of relaxin in the pig.