(A) Presecretory ameloblasts in P2 WT mice showed amelogenin protein mainly localized on the apical region of cytoplasm. (B) Besides the strong immunoreaction on the apical region, entire cytoplasm of presecretory stage ameloblasts in P2 TgLRAP mice showed highly intense amelogenin protein positive reaction. (C) Amelogenin protein was detected on entire cytoplasm and Tomes’ process of secretory stage ameloblast of P5 WT mice. (D) Secretory stage ameloblasts of P5 TgLRAP mice formed a disorganized layer and demonstrated amelogenin protein highly retained in the cytoplasm. (E) At maturation stage, ameloblasts of P10 WT mice were amelogenin immunopositive. (F) However ameloblasts in P10 TgLRAP mouse molars lacked polarity and were amelogenin immunonegative. Am, ameloblast; E, enamel; Od, odontoblast; D, dentin. Scale bar, 20μm.