Different nerve endings in the extraocular muscles. (A, B) An identified SNAP 25-positive spiral ending (A; green) was anterogradely labeled with CTB (B; red) after injection into the oculomotor nucleus tracer (case 2). (C) CTB-labeled en plaque endings (red) and TH-positive nerve ending (green), which does not contain tracer (case 2). (D, E) Tracer-negative (D) small nerve ending in the eye muscles stained for SNAP-25 (E) (case 1). (F, G) The synaptic endings of an anterogradely TMR-DA-labeled palisade ending (G; red) are visualized by immunostaining for synaptophysin (F; green) (case 1). (All images obtained with a DMRB fluorescence microscope; Leica, Bensheim, Germany). Scale bar, 20 μm.