Retention of Potential to Differentiate in Long-Term Cultures of Tooth Germs

When tooth germs derived from 14-day mouse embryos were cultured on gelatin sponges in vitro for 37 days, they lost their characteristic morphology, appearing as a layer of undifferentiated epithelium on the sponge surface, with the mesenchymal cells scattered throughout the interstices. These cultures were then transplanted subcutaneously into isologous, newborn recipients and, over a period of 56 days, developed into incisor teeth that were almost perfect in shape and structure.