Progesterone concentration in rabbit uterine flushings before implantation

Abstract

Departments of Obstetrics and Gynecology, Biochemistry, and Pediatrics, University of Colorado School of Medicine, Denver, Colorado 80220, U.S.A. Uteroglobin (or blastokinin) is a specific protein produced by rabbit endometrium when stimulated by exogenous or endogenous progesterone (Schwick, 1965; Beier, 1968a, b; Krishnan & Daniel, 1967; Urzua, Stambaugh, Flickinger & Mastroianni, 1970; Arthur & Daniel, 1972; Bullock & Connell, 1973). The protein is known to bind steroids, particularly progesterone (Urzua et al., 1970; Arthur & Daniel, 1972; Beato & Baier, 1975), and its role in early rabbit embryonic development may be that of a carrier protein for progesterone (Arthur, Cowan & Daniel, 1972; El Banna & Daniel, 1972a, b; Beato & Baier, 1975). Progesterone can be detected in 5- and 6-day post coitum rabbit blastocysts, 7-, 8- and 9-day post coitum blastocoelic fluid and in uterine washings from 5-day pseudopregnant rabbits (Beier, 1968b; Seamark & Lutwak-Mann, 1972). We now report measurements