Figure 4. Phenotype of osterix (Sp7)-deficient mice. Staining of skeletal preparations from embryonic day 15.5 (E15.5) and newborn homozygous mutant mice with alcian blue and alizarin red indicated a virtual absence of mineralization in all facial and skull bones formed by intramembranous ossification and a general deficiency of osteoblast differentiation. Reproduced with permission from Nakashima et al.(2002).