The role of innvervation in slow and fast muscle-motor unit formation will be studied in the chick embryo. Changes in NCAM and N-cadherin, cell surfaces molecules, in the process during which secondary myotubes partition off from primary myotube clusters will be investigated. The functional role of these cell surface molecules will be studied in ovo in the chick and in cell culture using blocking antibodies or enzymatic degradation. Finally, the roles of myotube cluster formation, synapse formation and functional innervation will be investigated in a series of transplantation studies in which small pieces of quail neural tube are transplanted into chick. These studies are unique in their approach in that they correlate molecular changes and cell-cell relationships with onset of neural function.
