DNA--cytometric studies on xenografts of squamous cell carcinomas of the head and neck.

The primary tumors of four human head and neck carcinomas and their xenografts in nude mice were analysed with respect to their histological features and DNA-ploidy level using DNA-flow and DNA-image cytometry. The histological characteristics of the xenografts and the DNA-index did not differ from those of the parent tumors, whereas the growth rate remained unchanged during serial passaging. DNA-flow cytometric analysis revealed the presence of both aneuploid and euploid cells in both parent tumors and their xenografts. During passaging the proportion of aneuploid cells increased. Analysis of the different cell populations by DNA-image cytometry revealed the presence of aneuploid tumor cells and euploid host cells. This study demonstrates that the characteristics of the original tumors in terms of histological features and DNA-ploidy are retained after xenografting.