Fig. 5. Endochondral bones in prx1cre;Ift^fl/n conditional mutant limbs are shorter than in wild-type littermates. Sections of hindlimbs from E18.5 wild-type (A,B), prx1cre;Ift88^fl/n (C,D), and prx1cre;Kif3a^fl/n (E,F) conditional mutant embryos were stained with H&E to analyze bone formation. Frozen sections through the tibia are shown. The overall size of the growth region in conditional mutants is reduced (double-headed arrows in B,D,F). Vascularization is evident in conditional mutant tibiae (asterisks in D,F), although the marrow cavity is poorly formed. (G,H) Cilia, as visualized by localization of acetylated -tubulin (green) and Ift88 (red), are apparent on the chondrocytes in control animals (G). By contrast, few chondrocytes in the developing tibia of prx1cre;Ift88^fl/n embryos (H) expressed a cilium.