TERMINAL SCHWANN-CELLS ELABORATE EXTENSIVE PROCESSES FOLLOWING DENERVATION OF THE MOTOR END-PLATE

Terminal Schwann cells, when stained for S100 (a calcium binding protein), can be seen to cap motor axons at the neuromuscular junction. Within days of denervation the Schwann cells begin to stain for the low affinity nerve growth factor receptor, but remain Thy-1 negative, and elaborate fine processes. These processes become longer and more disorganized over weeks, and cells positive for S100 and nerve growth factor receptor migrate into the perisynaptic area. Reinnervation results in a withdrawal of the processes. The morphology and location of terminal Schwann cells seems to depend on axonal contact. The spread of Schwann cells and their processes away from the synaptic zone following denervation, implies that these cells do not target axons directly to the endplate.