Methods: Tooth germs isolated from the lower first molars of embryonic 16-day (E16) ICR mouse were cultured by modified Trowel's method (Tabata et al., 1996). Culture was carried out in 5% CO2 at 37oC. Time-lapse photomicrographs were taken under the culture system of Tokai Hit Co. Ltd., Japan. Marker expression assays and histochemical analyses were carried out as described as before (Notani et al. 2009).
Results: Intact tooth germs and OEE removed tooth germs were cultured for 7 days, and analyzed by histology and immunohistology. By structural features, intact tooth germs showed normal development from early bell stage to late bell stage in which 6 cusps and 1 sub-cusp were well grown, and ameloblast and odontoblast have differentiated and secreted each matrix. While experiment tooth germs, which is excised OEE and a part of stellate reticulum, showed no repair of these excised tissues and even though the normal development as seen as intact tooth germ after same culture period.
Conclusion: Mandibular molar tooth germs prepared from E16 mice can develop in vitro normally without OEE under our culture condition. This indicates that tooth germs after bell stage develops and grows without OEE.