POTCs grow depending on Vegfr2. (A) Protocol for 4OHT injection. (B) Bright-field view of mandibles. Vegfr2^iΔEC mice exhibited impaired molar extrusions (arrowheads). (C) Tooth strength measured by a mechanical testing machine. A load was placed at the center of the molar at a rate of 2 mm/min until the molar broke, and maximum load (N) was measured as tooth strength (control [Cont] n = 3, Vegfr2^iΔECn = 3). (D–L) Section specimens at P12 and quantification (J, Cont n = 6, Vegfr2^iΔECn = 6; K and L, Cont n = 4, Vegfr2^iΔECn = 4). Vegfr2^iΔEC mice exhibited decreased POTCs (open arrowheads) associated with apoptosis (arrows), marked by cleaved caspase 3 (CC3). (M–S) Section specimens at P12 and quantification (Q and R, Cont n = 9, Vegfr2^iΔECn = 9; S, Cont n = 5, Vegfr2^iΔECn = 5). Vegfr2^iΔEC mice exhibited reduction in the height of odontoblasts (open arrowheads). Scale bars: 500 µm (B); 200 µm (D and E); 50 µm (F–I and M–P). Data are presented as means ± SD. Comparisons between two groups were evaluated using a two-sided Student’s t test.