Adhesion in skeletal muscle during regteneration

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Abstract
Adhesion molecules were studied in regenerating skeletal muscle immuno-histochemically and ultrastructurally after a standardized trauma. In normal muscle, extracellular matrix (ECM) protein tenascin was restricted to myo tendinous junctions (MTJ), while the integrin β1-subunit was present also on the sarcolemma. After injury, tenascin increased on the outer surface of regenerating myofibers, where cellular fibronectin also accumulated. Later tenascin concentrated at the tips of regenerating myofibers, where new MTJs were formed. The β1-subunit disappeared on necrotized myofibers aqnd reppeared on regenerating fibers in a thicker layer. The regener ating myofibers were invested by a basaql iamina, except, for the growth cones at the distal ends, which were laminin-nehative until the formation of MTJs occured. These results indicate that regenerating muscle cells are attached to the ECM in a way that allows both growth of the muscle cells across the scar and their use before the regeneration is completed.