Histological analysis of the abnormal calvarial sutures in Fgfr2+/P253Rmice. A-D) HE staining shows the abnormal development of the mutant coronal suture from P0 to P5 with presynostosis, disorganization of cells between the osteogenic fronts and osteoid deposition at P0 (A, B); and synostosis at P5 (C, D). E-H) HE staining shows the abnormal development of the mutant lambdoid (E, F) and sagittal suture (G, H) with proximate osteogenic fronts and cellular disorganization at P0. I, J) abnormal cartilage at the sagittal suture (blue arrows). Panels A, C, E, G and I are from littermate controls. Panels B, D, F, H and J are the corresponding regions in mutant mice. Black arrows, osteogenic fronts; arrowheads, presynostosis/synostosis. (Scale bars: A-D = 25 μm; E-J = 50 μm).