M-CADHERIN LOCALIZATION IN DEVELOPING ADULT AND REGENERATING MOUSE SKELETAL-MUSCLE - POSSIBLE INVOLVEMENT IN SECONDARY MYOGENESIS

In this work, we investigated the distribution of the Ca2+-dependent c ell adhesion molecule, M-cadherin, in mouse limb muscle during normal development and regeneration. Using two unrelated anti-M-cadherin pept ide antibodies, we found scarce M-cadherin immunostaining during prima ry myogenesis (E12-E14) with no accumulation at areas of cell-cell con tact. In contrast, the staining sharply increased in intensity at E16, remained high during secondary myogenesis(E16-P0) but disappeared soo n after birth. During secondary myogenesis, M-cadherin was specificall y accumulated at the characteristic sites of insertion of secondary my otubes in neighbouring primary myotubes. M-cadherin was also accumulat ed at the areas of contact between fusing secondary myoblasts and myot ubes in vitro. In the adult normal and regenerating muscle, we did not detect M-cadherin accumulations at the surface of myofibres. All toge ther, these observations suggest that M-cadherin is specifically invol ved in secondary myogenesis.