[Ultrastructural studies of tumors transplanted into nude mice using the TTK-1 cell lines derived from normal human early decidual tissue].

: Tumors transplanted into nude mice using the TTK-1 cell lines [TTK-1(E) and TTK-1(F)] derived from normal human early decidual tissue were studied morphologically. The epithelial-like cell line TTK-1(E) and the fibroblast-like cell line TTK-1(F) were maintained in culture through one hundred and ten subcultures since July 1979. Rapidly growing tumor nodules formed at the implantation sites. The incidence of tumor growth was 100% for both cell lines. Histologically the tumors were composed of poorly-differentiated cells arranged in a cord-like structure and showed typical malignant characteristics. Immunohistochemical studies, electron microscopy and immunocytochemical studies revealed that the tumors from the two cell lines differed in many respects. The tumors formed by TTK-1(E) showed epithelial characteristics and the tumors formed by TTK-1(F) showed both epithelial and mesenchymal characteristics. Therefore, TTK-1(E) might be useful as an in vitro model of endometrial cancer and TTK-1(F) as an in vitro model of both endometrial cancer and endometrial stromal tumor (containing mixed mesodermal tumor). These tumors will be valuable for future studies of the tumorigenicity and therapy of uterine malignant tumors. They may reflect the various functions of decidual tissue.