Fig. 8. Aetiology of the split nose phenotype. The nasal processes of Alx3/Alx4^lst-J double mutant embryos fail to fuse around E11.5. Shown are frontal views on control (A-D; either Alx3^+/- or wild type) and stage-matched Alx3/Alx4^lst-J double mutant embryos (E-H) of E10.5 to E11.5 as indicated above photos. Posterior regions of most of the embryos were cut off to allow free view on the nasal processes. In embryos at E11.5, the Alx3 expression domain was visualised by X-Gal staining to detect ß-galactosidase. Arrowheads point to medial edges of the medial nasal processes, demonstrating the improper outgrowth and fusion of the nasal processes in double mutant embryos. Note the increasing difference in distance between the processes of control and Alx3/Alx4^lst-J double mutant embryos.