Scanning electron microscopy of cartilage in mice with hereditary chondrodysplasia.

Mice born with hereditary, recessive chondrodysplasia (cho/cho) are dwarfed because the cartilage model upon which the endochondral osseous skeleton develops is defective. The mutant's cartilage matrix lacks cohesiveness which apparently contributes to the absence of columnar alignment of proliferating epiphyseal chondrocytes in developing tubular (long) bones. The present communication reviews our current understanding of skeletal dysplasia as it relates to defective chondrogenesis, and presents observations made with the scanning electron microscope of cellular disarray and nonuniform size and distribution of collagen fibrils which confirm the existence of a matrix defect. Autoradiographic experiments on tibial cartilage, similar to those performed on sternal cartilage, confirm the normal pattern of sulfate labeling by mutant epiphyses.