The structure of tumours derived from mouse cells after "spontaneous" transformation in vitro.

The histological structure of 58 primary tumours derived from spontaneously transformed tissue culture cell lines from embryonic (14-16 days), young (3-20 days) and old (28-34 months) C3H and C57 mice is described. Although the cell lines were derived from a number of different organs the tumours were similar in morphology. The pattern was mixed, with "fibrosarcomatous", "myxoid", "epithelioid" and giant cell areas. The tumours resemble some types of haemangiopericytoma.