Localization of alpha‐fetoprotein in transplantable murine teratocarcinomas

Abstract

Abstract Embryo‐specific serum component α‐fetoprotein (AFP) was localized by the indirect immunofluorescent technique on paraffin sections of transplantable teratocarcinoma of strain 129/SV‐S1 CP mice. AFP was found in several types of structures comprising an insignificant part of the total section area. Most frequent and bright AFP‐specific fluorescence occurred in the epithelium of endodermal origin lining cysts and tubules; in addition, AFP was found in sheets of cells, groups or individual cells of non‐identified origin and in squamous epithelium arranged in pearls. In cysts and granules isolated from the ascitic fluid, developing after an intraperitoneal injection of teratocarcinoma suspension, AFP was found in cells of the external layer, very similar to those of the visceral yolk sac, and in the embryotype mesenchyme inside the cysts. By analytical disc‐electrophoresis in polyacrylamide gel, cysts were found to contain albumin, AFP, transferrin and gamma‐globulin, the relative proportion of AFP being considerably higher than in the ascitic fluid as compared with the other proteins mentioned. It is suggested that AFP localization in teratocarcinomas corresponds to the sites of its synthesis in the embryo and that AFP synthesis is a specific function of certain forms of endodermal differentiation.