Human pleomorphic adenomas transplanted to nude mice.

Tissue from 13 human pleomorphic adenomas was transplanted to a total of 64 nude mice. Eight of the tumors were transplanted into a second passage of mice, 17 in all. In 39 mice of first passage, there was a definite increase in graft size. Microscopic examination showed no change in the histologic pattern from the donor tumor to the transplanted tissue. The heterochromatin pattern after staining with the DNA-specific fluorochrome D287/170 allowed distinction between human and murine cells and showed that both epithelial and mesenchymal cells were of human derivation. Autoradiographic studies with tritiated thymidine showed that both epithelial and mesenchymal tumor cells were labeled. Our results thus show that cell proliferation in the human pleomorphic adenoma takes place in epithelial areas as well as in mesenchymal areas.