Fig. 7. Analysis of 18.5 dpc Ihh^-/- mutant mouse embryos. The skull of wild-type (WT) embryos (A-C) is larger than that of mutant siblings (D-F). Notice the presence of the ossified basal cranial bones in the mutant. Arrows indicate the leading edge of the mineralized dermal calvarial bone. Expression of the early osteoblastic markers, such as Runx2 (G) and Osx (H), is severely reduced in the Ihh^-/- condition (K and L, respectively). Red brackets indicate area occupied by undifferentiated proliferating osteoblasts. The expression of Opn (I,M), a marker for more mature osteoblasts, is unaltered or slightly expanded in the mutant condition. Green brackets indicate area occupied by differentiated mature osteoblasts. (J,N) H&E stainings of wild-type and mutant dentary bones, respectively. bas, basisphenoid; boc, basioccipital; dnt, dentary; exo, exoccipital; fnt, frontal bone; int, interparietal; max, maxillary; MC, Meckel's cartilage; nas, nasal; pal, palatal; par, parietal; pte, pterygoid; o.t., os tympanicum. Scale bars: 1 mm in A; 200 µm in G.