Induction of synaptic extracellular matrix molecules at ectopic neuromuscular junctions.

The induction of synapse-specific molecules recognized by peanut agglutinin (PNA) was examined at ectopic neuromuscular junctions in adult frog muscles using light and electron microscopy. In normal frog muscles, PNA specifically recognizes the extracellular matrix at neuromuscular junctions but not at extrajunctional regions. This report shows binding of PNA at ectopic neuromuscular junctions which were initially extrasynaptic and hence unrecognized by PNA. Results suggest that synapse-specific extracellular matrix molecules can be induced de novo at new junctional sites.