Figure 2. Loss of Smad4 in the dental epithelium prolongs the maintenance of the cervical loop and molar crown development.
(A) Timing of doxycycline induction and sample harvest in control and KRT14-rtTA;tetO-Cre;Smad4fl/fl (K;T;S) mice. (B-E) Macroscopic views (B), quantitation of the crown length (C) and H&E staining (D, E) of PN21.5 control and KRT14-rtTA;tetO-Cre;Smad4fl/fl lower first molars. Arrows indicate crown length. N=3. *, p < 0.05. Error bars indicate standard deviation (SD). (F-Q) Time-course analysis of H&E staining (F, G, J, K, N, O) and Keratin 14 (K14; green) immunofluorescence (H, I, L, M, P, Q) of control and KRT14-rtTA;tetO-Cre;Smad4fl/fl lower first molars at PN7.5 (F-I), PN12.5 (J-M), and PN21.5 (N-Q). Arrows indicate the HERS in control lower first molars. Broken lines indicate the cervical loop in KRT14-rtTA;tetO-Cre;Smad4fl/fl lower first molars. M1: Lower first molar; M2: Lower second molar; R: Root. Scale bars (D, E): 500μm. Scale bars (F-Q): 50μm.