FGFR3 and achondroplasia: As gain-of-function mutations of FGFR3 lead to craniosynostoses in both ACH patients and mouse model 7,36,37, Alizarin red staining and transgenic line Tg(osterix:EGFP) that labels osteoblasts were employed to image the cranium development in vivo dynamically from 1 month (SL 10.0 mm), 1.5 month (SL 14.0 mm) to 2 months (SL 18.0 mm).