Secretory function of cells in the rat metrial gland

The immunochemical determination of antigens, products of the secretory activity of metrial gland cells, in the serum of pregnant rats is described. In order to prepare a specific immune antiserum, rabbits were immunised with homogenates of the rat metrial gland removed at day 15 of pseudopregnancy. The resultant immune antisera were adsorbed by glutaraldehyde-polymerised sera from nonpregnant rats until the Ouchterlony test ceased to give a positive reaction with sera of nonpregnant rats. These adsorbed specific sera continued to react with sera of pregnant and pseudopregnant animals, indicating that the latter both contain one or more antigens identical to those produced by the cells of the metrial gland, and against which the specific antisera had been raised. When 10% and 15% fresh serum from nonpregnant females was added to molten agar or was initially dropped into wells in the agar, the positive reaction between the specific antisera and the sera of pregnant and pseudopregnant rats was not eliminated. An antigen identical to the serum antigen was also found in amniotic fluid, in sera, and in extracts of metrial glands from pregnant and pseudopregnant laboratory animals. The data obtained indicate that cells in the metrial gland have a secretory function. It is proposed that the serum antigen of pregnant and pseudopregnant rats is secreted by the granular cells in the metrial gland.