[Developmental potency of teratocarcinoma cells in chimeric embryos]

The developmental potential of various teratocarcinomas of different origins was examined by making chimeras with mouse embryos. Of 7 teratocarcinoma lines examined, only 2 were found to contain stem cells having the ability to form live-born chimeras; one was experimentally induced OTTBALB-2 and the other was spontaneously occurring STT-3. The latter showed remarkable ability to colonize mid-gestational fetuses and adults. This result not only demonstrates that EC cells of male primordial germ cells have the ability to form viable chimeras but also suggest that this kind of tumor is a useful source of EC cells to make chimeras. The advantage of using pluripotent cell lines such as EC cells or embryonic stem (ES) cells as a vector for introducing foreign genes into mouse embryos was discussed in relation to the study on gene function and on gene regulation during development.