Tom Glaser, Associate Professor, Department of Internal Medicine, University of Michigan Medical School

This retina of a laboratory mouse is viewed with Nomarski optics and stained with an antibody to identify ganglion cells, cone photoreceptors and the inner plexiform layer (brown). A quarter of a millimeter across, this layered tissue covers the inside surface of the eye. The human retina is similar, and functions as a highly organized switchboard that records, processes and conveys all visual information from the outside world to the brain. In this picture, light first passes through the lens and then enters the retina to excite the cone and finger-like rod photoreceptors located at the back of the eye near the pigmented epithelial layer (black). The resulting electrical signals are then relayed stepwise, via delicate neural tendrils, to the ganglion cells, whose projections join to form the optic nerve and travel to the brain.