Protein Synthesis in Yolk Sac Tumor: Histochemical Studies of Human and Rat Yolk Sac Tumor

Abstract

Synthesis of various serum proteins, such as albumin, prealbumin, α1‐antitrypsin, transferrin and α‐fetoprotein, by human and rat yolk sac tumors was studied by indirect immunofluorescence and immunoperoxidase techniques. These serum proteins were found to be present in the cytoplasm of tumor cells forming the lining of vitelline cysts, as well as Schiller‐Duval bodies and vacuolated meshwork on histological sections. Two of these tumors were cultured. Immunopathological studies revealed that albumin, prealbumin, α1‐antitrypsin, transferrin and α‐fetoprotein were found in the cytoplasm of these cultured tumor cells. The immunofluorescence of these proteins was also found on the PAS‐positive granules, which existed intra‐ and extra‐cellularly.The ability to synthesize these serum proteins of these tumor cells was not affected by tissue culture and was maintained during subcloning.It was demonstrated by electron microscope ferritin antibody technique that α‐fetoprotein was mainly synthesized on the ribosomes of the rough endoplasmic reticula of rat yolk sac tumor cells.