Cellular aspects of elastogenesis in the elastic tendon of the chicken wing

Morphological, immunocytochemical and ultrastructural methods were used to investigate the role of cells during elastogenesis in the elastic tendon of the chicken wing. Intimate contact of the cell processes with elastic fibers was observed in adult birds. During development there was a sequential appearance of microfibril bundles that became progressively impregnated with amorphous elastin, which eventually predominated in fully developed elastic fibers. The growing elastic fibers were usually enveloped by recesses of the cell surface. The tendon cells were polarized in their association with fibrous components of the extracellular matrix. This arrangement suggests that these cells secrete and organize elastic and collagen fibers to different extracellular compartments. These results show that cells are intimately involved in producing components of different extracellular matrix fibers, in controlling their assembly, and in defining their borders and associations during development.