Fig. 4.

Melanopsin-expressing retinal ganglion cells and myelin ultrastructure. a Retinal cross-sections from a healthy control individual were stained with antibody against melanopsin. The inner retina shows the ganglion cell layer with retinal ganglion cells (arrows) and one melanopsin-expressing retinal ganglion cell (asterisk). b The inner retina from a patient with LHON reveals a melanopsin-expressing retinal ganglion cell (asterisk) in the complete absence of other retinal ganglion cells. c Electron micrograph of optic nerve cross-sections from a healthy control individual showing densely packed axons with variable axonal calibre and normal myelin thickness. d A representative illustration from a patient with LHON highlights the dramatic depletion of axons with a thin myelin coating around the surviving axons