Mouse odontogenesis in vitro: the cap-stage mesenchyme controls individualmolar crown morphogenesis

Day 14 ICR mouse first lower (M-1) and upper molars (M-1) as well as hetero topic recombinations of M1 epithelium/M-1 mesenchyme and M-1 epithelium/M-1 mesenchyme were cultured for 6, 8 and 10 days on semi-solid medium. Comput er-assisted 3D reconstructions were performed to follow the in vitro develo pment of these explants. in vitro culture of cap-stage molars allowed for t he emergence of unequivocal morphological features distinctive for M-1 vers us M-1 including the cusp pattern, cusp inclination and tooth specific chro nology for odontoblast and ameloblast terminal differentiations. Both M-1 e pithelium/M-1 mesenchyme and M-1 epithelium/M-1 mesenchyme recombinations d eveloped according to, the known developmental fate of the mesenchyme. Our data demonstrate that the cap-stage dental ecto-mesenchyme not only directs tooth class specific morphogenesis, but also individual molar crown featur es. Furthermore, the mesenchyme apparently also controls the typical mirror symmetry of right and left handed teeth.