Fig. 2. Gross calvarial malformations in En1^-/- mice. (A) Schematic diagram and staining at P1. (Aa) Schematic depicting the organization of the murine skull vault consisting of: the paired frontal bones (F), the paired parietal bones (P) and the interparietal bone (IP). These are intervened by the lambdoid, coronal, sagittal and interfrontal (metopic) sutures. (Ab,Ac) Alizarin Red and Alcian Blue staining of mineralized bone and cartilage, demonstrating a generalized calvarial hypoplasia, coronal and lambdoid suture gaping (arrow, double-headed arrow), and frontal foramina (asterisk) in the skull vault of En1^-/- mice at P1. (B) At P35, En1 mutants (Bb,Bd) exhibit abnormal coronal, lambdoid and interfrontal suture patency (Bb, arrows, asterisk), and severe malocclusion due to maxillary and nasal bone hypoplasia (Bd, arrow, arrowhead) compared with wild type (Ba,Bc). Scale bars: 2 mm in A; 5 mm in B.