Immunohistochemical detection of an epithelial membrane protein in rat embryos at different stages of development

This study aimed to describe the distribution of a membrane protein called Gz-1-Ag in embryonal rat tissues using monoclonal antibodies. Three monoclonal antibodies recognizing different antigenic determinants of Gz-1-Ag were tested on different stages of rat embryos-fertilized oocytes, two-cell stages, morulae, blastocysts and embryos up to 17.5 days old. The embryos were fixed by different methods; the Tokuyasu method was the most convenient. It yielded very good morphological conservation, good preservation of antigenicity and weak background fluorescence. Gz-1-Ag was detected in practically all early epithelial structures, but the intensity of fluorescence varied. Fluorescence was not associated with the germ layer from which the epithelium derived. The uninterrupted presence of Gz-1-Ag from the fertilized oocyte to all subsequently arising epithelial structures suggests a role of Gz-1-Ag in cell adhesion, secretory processes or the intercellular exchange of information or substances.