Morphogenetic rearrangement of injected collagen in developing chicken limb buds.

Publisher Website
Google Scholar
Abstract
A fundamental question concerning the development of the extracellular matrix is what factors control the arrangement of collagen fibrils within a tissue and at the same time allow for great diversity of geometric forms exhibited by collagen. Physical forces within the embryo may serve to organize collagen fibers into regular patterns. In particular, the prediction that patterns of stress having this morphogenetic function are generated in cell traction, the contractile force exerted by cells to propel themselves, is tested. To study the effects of these mechanical forces on the extracellular matrix, type I collagen was fluorescently labeled and injected into developing chicken wing buds. When the injected limbs were allowed to develop and then examined histologically, the exogenous collagen was found incorporated within normal connective tissues of the wing. The labeled collagen became arranged according to its site of injection, forming parts of tendons, perichondria, cartilages, perineuria and blood vessels. Since the injected collagen formed a gel within minutes of its injection, the subsequent incorporation of this preformed collagen within organized structures cannot be explained in terms of molecular self-assembly or other mechanisms occurring during collagen deposition. Within developing tissues, patterns of forces exist that are capable of physically rearranging collagen and determining its long-range order.