Figure 2.

Node of Ranvier labeling in the PNS (rat and mouse sciatic) and CNS (rat optic nerve). Immunofluorescence with anti-Na_v1.6 antibody (red) and anti-caspr (green). Anti-caspr labeled the paranodal region on either side of the nodal labeling by anti-Na_v1.6. (A) Rat sciatic nerve. All nodes labeled by caspr were labeled for Na_v1.6. (A Inset) Another node viewed obliquely such that the circumferential labeling of axonal membrane can be seen. (B) Mouse sciatic nerve. Labeling controls for Na_v1.6 and caspr. (B1) Wild-type mouse labeled for Na_v1.6 (red) at nodes shown by caspr labeling (green). (B2) Mutant mouse (med^J) lacking Na_v1.6 had no labeling for Na_v1.6 at nodes. (B3) One node illustrating that preincubation of the anti-Na_v1.6 antibody with the peptide eliminated nodal labeling in the wild-type mouse. (C) Optic nerve axons. Optical sections (0.2 μm apart; n = 25) were deconvolved and projected onto a single plane. Every node was labeled for Na_v1.6 (caspr labeling in the figure without Na_v1.6 labeling was at the top or bottom of the series of sections). (C Inset) Two nodes, one viewed longitudinally and one viewed transversely such that the nodal labeling appears circular. (Bars = 5 μm for A and C, 3.3 μm for A Inset and C Inset, 6 μm for B1, 10 μm for B2, and 13 μm for B3.)