A transplantable pulmonary tumor line in mouse forming bone and chondroid tissue

A spontaneous papillary adenocarcinoma was found in the lung of an A/St female mouse 20 months of age, and its transplantable line forming bone and chondroid tissue was established. The basic patterns changed from papillary adenocarcinoma to anaplastic carcinoma or a fibrosarcoma-like pattern through tubular adenocarcinoma. Osseous tissue appeared in the 1st transplant generation and increased with serial transplantations. In the 5th transplant generation, abundant osseous tissue was seen, a fibrosarcoma-like pattern became predominant and chondroid tissue appeared. Morphologically, the fibrosarcoma-like pattern was proved to be epithelial in nature. Marked alkaline phosphatase activity was demonstrated in the spindle-shaped tumor cells, and the activity obviously elevated in the serum of hosts bearing tumors which included more spindle-shaped cells and osseous tissues than chondroid ones. It is presumed that the osseous and chondroid tissues formed by carcinoma cells did not result from metaplasia in the strict sense of the word but rather from pseudometaplasia or metamorphosis.