Immunocytochemical localization of relaxin in endometrial glands of the pregnant guinea pig.

Relaxin was localized in the cytoplasm of endometrial gland cells in the uterus of day 60 pregnant guinea pigs with the peroxidase-antiperoxidase method. The immunoprecipitate was located over the apical portions of the glandular cells. Stain was not found over non-endometrial portions of the uterus, endometrial surface epithelium or cells of the uterine cervical glands. Agar double-immunodiffusion analyses demonstrated a reaction of identity when extracts of uterus from day 60 pregnant guinea pigs and a porcine relaxin standard were tested with an antiserum produced against highly purified porcine relaxin. An extract of uteri from day 60 pregnant guinea pigs gave a positive response in the mouse uterus bioassay for relaxin.