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.

Different antigen expression on Wolffian and Müllerian cells in rat embryos as detected by monoclonal antibodies.

The Wolffian duct and the developing Müllerian duct of 14 and 15 day old rat embryos were examined with the monoclonal antibodies GZ1 and GZ2. These antibodies react with antigens situated in the cell membrane of Wolffian cells; they do not react with Müllerian cells. This different antigen expression confirms the current opinion that these cells are of different types. A cellular contribution from the Wolffian duct to the developing Müllerian duct was not found.

Contacts between Wolffian and Müllerian cells at the tip of the outgrowing Müllerian duct in rat embryos.

The developing Müllerian duct was studied at the light microscopic as well as the electron microscopic level in rat embryos, especially in the section of the terminal bud and its tip, where Wolffian and Müllerian duct are enclosed by a common basal membrane. In this zone desmosomes can be found among Wolffian cells and also among Müllerian cells. In addition, we found cell contacts between Müllerian and Wolffian cells, namely short electron-dense segments on adjacent surfaces or disc-shaped thickenings within opposite plasma membranes, as well as fusions of the plasmalemmata over short distances. Until now, these cell contacts have not been described in rat embryos.