The multipotential stem cell of the murine teratocarcinoma, embryonal carcinoma (EC), is capable of differentiation in vivo and in vitro to nonneoplastic progeny. Undifferentiated EC cells, spontaneously differentiating teratocarcinoma cells, and differentiated cells derived from EC cells were analyzed for DNA content and chromosome number distributions. Flow microfluorometric and fluorescence cytophotometric analysis of DNA content showed that EC cells had a characteristic diploid (2c) distribution, whereas several differentiated cell lines derived from EC cells had 4c DNA distributions. The tetraploid cell populations studied were capable of cell division but had restricted differentiative potential and were either of low tumorigenicity or nontumorigenic. In vivo teratocarcinomas, comprised of both EC cells and differentiated cell types, contained diploid and tetraploid populations. Chromosomally, EC cells were near-diploid (39 chromosomes) and differentiated cells were near-tetraploid (62 to 76 chromosomes). The teratocarcinoma provides a model for studying the basic mechanisms that control the growth dynamics of the rapidly and slowly proliferating cell populations present in many tumors.
This work was supported by Grants CA-16030, CA-13419, and CA-15823 from the National Cancer Institute, by a grant from the Milheim Foundation, and by the United States Energy Research and Development Administration.