Hyperploid cells in the limb buds of rats and 5-azacytidine-induced digital deformities

To clarify the mechanism underlying the digital teratogenesis of 5-azacytidine (5-AC), the DNA contents of mesenchymal cells were examined in the limb buds of the rat by microspectrophotometry. 5-AC induced hyperploid cells: 2.4% at 18 h after injection and 3.2% at 24 h. No hyperploid cells were noted 30 h after the treatment. Because posttreatment caffeine suppressed 5-AC-induced digital defects, the actions of caffeine on 5-AC-induced hyperploid cells were further studied; no hyperploid cells were detected at any sampling point. Caffeine suppressed hyperploid cells as well as digital defects. These results suggest that the causative factors of digital defects by 5-AC may involve hyperploid cells. However, in that there were too few hyperploid cells to cause the defects, further studies are required to clarify the nature of the action of 5-AC.