Establishment and Characterization of a Rat Yolk Sac Tumor Cell Line, NMT‐1, Producing α‐Fetoprotein, with Potential for Lymphatic Metastasis

A new cell line producing α‐fctoprotein, designated NMT‐1, was established from rat yolk sac tumor with the potential for lymphatic metastasis in inbred Wistar rats. In this paper, we investigated the characteristics of NMT‐1 cells. The cell line grew in a monolayer and had a polygonal epithelioid appearance in phase‐contrast microscopy. The doubling time of NMT‐1 cells during exponential growth was approximately 16 h in RPMI‐1640 with 10% fetal calf serum. The D(0) value for radiation sensitivity was 97 ±3 cGy. The extrapolation number, n, for NMT‐1 was 1.08 ± 0.15, In the log phase, the G(0)/G(1), S and G(2)/M fractions were 23.2%, 62.1% and 14.3%, respectively. Tumor take was observed in all of the rats inoculated with NMT‐1 cells. In the case of flank tumor, the mean survival time was 104 days after inoculation with 10(6) tumor cells. Inguinal, axillar, paraaortic, mesenteric and mediastinal lymphnode metastases were observed in all rats inoculated with NMT‐1 cells. Rats which survived for a long time developed metastases in a lymphatic vessels of the liver, lung and/or kidney microscopically. The biological behavior and the histopathological features of the tumor induced by inoculation with NMT‐1 cells were the same as those of the original tumor induced by fetectomy.