AbstractWe have previously localized an antigen of oviductal origin to the zona pellucida of superovulated hamster oocytes (Kan et al.:Journal of Histochemistry and Cytochemistry36:1441—1447, 1988) and described the intracellular distribution of this antigen in the oviductal epithelium (Kan et al.:Biology of Reproduction40:585—598, 1989). These results led to our hypothesis that the oviduct is a bona fide site of origin of certain components of the zona pellucida. In this report, using the high resolution lectin‐gold approach withHelix pomatialectin (HPL)‐colloidal gold complex, we present cytochemical evidence to show that glycoconjugates containing terminal N‐acetyl‐D‐galactosamine residues are absent from the zona pellucida of ovarian oocytes but are synthesized and secreted by the nonciliated secretory cells of the oviduct and later become associated with well‐defined structural elements of the zona matrix of oocytes during passage through the oviduct. The nature of the HPL‐binding glycoconjugates was determined by biochemical analyses. Electrophoretic and immunological experiments demonstrated that the glycoconjugates correspond to the high molecular weight polydispersed glycoprotein that we have previously described. We have designated this glycoprotein “hamster oviductin 1” (IIm OV‐1). Our results further substantiate the belief that the oviduct is a source of origin of zona