Antibodies against zona pellucida (ZP) have recently aroused interest for their contraceptive activity in vitro and in vivo. In our study we attempted to use anti-ZP antibodies for detection of binding sites for ZP antigens on the oviductal epithelium considering the fact that in the course of fertilization and early stages of embryonic development the ZP is denuded and comes into intimate contact with the lining of the oviduct. The binding sites for anti-rat ZP antibodies (ARZPAb) prepared by immunization of a BALB/c mouse were detected using an indirect immunoperoxidase technique on the ZP of oviductal oocytes and on the luminal surface of the oviductal epithelium of the isthmus under the light microscope. For the electron microscopic detection of binding sites for anti-rat ZP antibodies post-embbedding immunogold technique was used. The binding sites were expressed in the ZP and on the apical membrane of the oviductal epithelium as well. The TEC-02 IgM monoclonal antibody recognizing the TEC-2 epitope carried on the ZP of a mouse egg was used for detection of the binding sites in the mouse. The binding of TEC-02 antibody was confirmed in the ZP of ovarian oocytes. In the fimbrial and ampullar parts of the oviduct the binding sites were detected on individual epithelial cells, in the isthmus the expression of TEC-2 epitope was more frequent. No binding sites for anti-ZP antibodies were found in the uterine and vaginal epithelium. The findings of binding of ARZPAb detected on the oviductal epithelium of the rat and mouse support the hypothesis of the presence of membrane receptors for ZP antigens in the oviduct.

Keywords: oviduct, Zona Pellucida, Binding Sites, Antibodies, antigen determinants