Mouse Genome Informatics
involves: C57BL/6
phenotype observed in females
phenotype observed in males
N normal phenotype
• although bone length is normal, 28% of heterozygotes have exostoses on the ribs, but not on the long bones, which are located near the costochondral junction and are composed of cortical and medullary bone with an overlying hyaline cartilage cap
• at E18.5 there are no morphological abnormalities in the unla, radius, or femur and mineralization of the cartilage matrix, formation of the bony collar surrounding the hypertrophic chondrocytes and formation of the trabecular bone appear normal
• each rib has nodules or single misplaced chondrocytes with overlying perichondrium
• although chondrocytes do produce heparan sulfate and no aberrant hedgehog activity is found in the chondrocytes, chondrocytes in the proliferative zone of E18.5 ulnae lack columnar organization
• the expression domains of Pthr1 and Ihh in E18.5 ulnae growth plates are slightly smaller than normal

Mouse Models of Human Disease
Exostoses, Multiple, Type II 133701 J:103125