Cover legend: This illustration shows one optic nerve from a C57BL/6 mouse brain. Astrocytes are labeled with GFAP (red) and oligodendrocytes are labeled with APC (green). Cell bodies are labeled with the nuclear marker DAPI (blue). The mouse optic nerve is a purely myelinated white matter tract and provides a novel model for studying preconditioning in white matter. For more information, see the article by Hamner et al. (pages 15599–15611).