Morphological studies on the established cell lines obtained from normal human decidual tissue of an early stage of gestation.

The two cell lines, TTK-1 (E) and TTK-1 (F), were established from normal human decidual tissue of early gestation. The primary culture was initiated by a fragment culture technique in July, 1979 and the cultures were passaged about once every two months. Meanwhile two kinds of the cultures, the epithelial-like cell dominant one and the fibroblast-like cell dominant one, had appeared. The former has been subcultivated and maintained at a constant growth rate and designated as the TTK-1 (E) cell line. The latter showed a gradual decline in growth rate and finally growth ceased at 3 years after the initiation of the culture. The sudden onset of growth and colony formation occurred after 4 months of senescence and the fibroblast-like cell culture has been maintained at a constant growth rate and designated as TTK-1 (F) cell line. Morphological studies revealed that the TTK-1 (E) cell line had epithelial-like characteristics and TTK-1 (F) cell line had fibroblast-like features. Both cell lines showed heteroploid karyotypes and tumorigenicity in nude mice transplantation. The two cell lines appeared to be established by spontaneous neoplastic transformations and should be useful cellular models for the study of malignant endometrial tumors.