Uteroglobin as progesterone-binding protein in the preimplantation uterine epithelium of the rabbit: histochemical studies.

[3H] progesterone was injected into the uterine lumen of rabbits toward the end of preimplantation period (162 h post coitum). Light-microscopic autoradiography showed accumulation of label in single cell groups of the uterine epithelium. Fluorographs of thin layer chromatograms of steroid extracts indicated the metabolization of progesterone in the uterine tissue. Incubation of uterine sections with fluorescein isothiocyanate-conjugated progesterone-rabbit serum albumin revealed binding sites for this reagent: 162 h post coitum, staining was also localized in single cell groups of the uterine epithelium. Pretreatment with a monospecific antiserum showed uteroglobin to be the binding protein.