Fig. 3. Analysis of malleal/gonial bone fusion in Bapx1+/- neonatal mice. Alizarin Red staining of dissected middle ears from P2 wild-type (A,B) and Bapx1 heterozygous (C,D) mice. In Bapx1^+/- neonatal mice, hypoplasia of the gonium resulting from the loss of one copy of the Bapx1 gene is still evident (black arrowheads). Despite this, these mice show signs of fusion between the gonium and the malleus (white arrowheads in inserts indicate extremities of fused region). In all adult heterozygous mice examined to date, the malleus has been found to be fused to the tympanic bone (data not shown). M, malleus; Ty, tympanic ring.