Nodes in the CNS of Caspr mutants increase in length with age. Optic nerve sections from age-matched wild-type and Caspr knock-out mice at 3 weeks, 6 months, and 2 years of age stained forβIV spectrin are shown (a-f). Scale bar, 10 μm. Node lengths were quantitated (g) and are presented as means ± SEM. In the sciatic nerve (SN), the length of the node in both wild-type and Caspr mutant mice increases slightly with age. In the optic nerve (ON), the length of the node decreases slightly in the wild-type mice but increases substantially with age in the Caspr mutant. Nodes are significantly longer in the Caspr mutants than age-matched wild-type nerves in both the CNS and PNS at all ages (*p < 0.0001).