[Study on heterotransplantation of malignant urogenital tumors in nude mice: results of transplantation and the characteristics of the explants].

Since 1976, we have transplanted 82 urological neoplasms into nude mice, 46 of which (56%) took. Thirty five of them (43% of the total tumors) are being serially transplanted. This rate of success seems to be better than that obtained at other institutes for both neoplasms of urogenital as well as other tissue origin. The explants basically retained the original characteristics of the native tumors not only in histological pattern but also in tumor markers, even after a long term period of heterotransplantation. However, the histological features of some tumor lines seemed to be reduced. A certain cell population was lost during repeated transplantations. Such a clonal selection may have resulted from the outgrowth of the cell population capable of adapting to the transplanted environment. Nevertheless heterotransplantation experiments in nude mice are one of the most valuable tools in various cancer research including that in the urological field since a rather high percentage of urologic malignancies take while retaining their original characteristics for a long time.