An animal model of lymphatic metastasis using the ascites-form of the murine testicular teratocarcinoma (402AX).

We examined the ascites-form of the murine testicular teratocarcinoma (402AX) as an animal model of spontaneous metastasis. We inoculated 2 x 10(5) cells into a total of seven hundred and twenty-seven 129/J strain mice. They showed clinically manifested ascites approximately two weeks later and died three to nine weeks later. Metastases were seen in lungs and hilar lymph nodes two to three weeks later. We performed staging and developed a definition of metastasis. Pulmonary metastases were quantified by mapping and counting the number of metastatic nodules in the lungs. Lymph node metastases were quantified by measuring the maximum diameter of metastatic lymph nodes (tumors). Additional sectioning was shown to be beneficial to demonstrate lymph node metastasis. The macroscopical metastatic rate was much less than the microscopical metastatic rate. The metastatic rate of the natural-death mice was much higher than that of the sacrificed mice. Lymph node metastatic rate was much higher than pulmonary metastatic rate. The metastatic rate had a direct relationship with the volume of ascites. This animal model can be used to study spontaneous metastasis.