Figure 2.

Experiments by Mintz and Illmensee: Metastatic melanoma was produced by placing a 6-day male 129 embryo under a testis capsule. Ascites tumor of embryoid bodies was generated and was maintained in 200 transplant generations. The malignant core cells were injected into blastocysts from parents of C57BL/6 mice, which were then transferred to the uterus of pseudopregnant mothers. Normal mice, which were chimeras, were born with coal-colored mosaicism or internal tissue contribution of the 129 tumor cells. A mosaic male produced viable sperm of the 129 genotype. Despite originating from malignant cells, the progeny did not produce tumors. Figure source: Mintz B, Illmensee K, 1975.⁸¹ Reprinted with permission from the author.