What regulates the timing of these cellular contacts is another question. Timing is also regulated by the acquisition of ectodermal competence to respond to induction. Ectoderm from the early neural tube will not respond to inductive influences produced by the hindbrain of late nerulae and ectoderm from beyond neurulation doesn't respond either. Structures other than sense organs 1. Mammalian tooth induction .
Ameloblasts arise from epithelium, the oral epithelium.
Odontoblasts arise in the neural crest. Odontoblasts are formed from these cells after a series of epigenetic interactions with the overlying epidermis. The critical factor is that the mesenchymal cells stop migrating and settle down against the buccal epithelium at the locations of the future teeth. We might like to ask ourselves why they stop precisely in those positions, but we shall come back to the whole question of spatial analysis later. The dental papilla then induces the epithelium to form an enamel organ.