Vernon Davis, Chris Cook, Chad GreenwaySan Francisco 49ers tight end Vernon Davis, top, is tackled by Minnesota Vikings outside linebacker Chad Greenway and cornerback Chris Cook, right, after making a reception during the second half of an NFL football game Sunday, Sept. 23, 2012, in Minneapolis. The Vikings won 2413.(AP Photo/Genevieve Ross).The visual signal is then transmitted to the innermost nuclear layer of the retina, called ganglion cell layer (GCL), via the inner plexiform layer. Ganglion cells send their axons through the optic nerve to form connections with specific targets in the brain, resulting in the projection of the visual image to the brain (Dowling, 1987). These six classes of neuronal cells as well as the M glial cells, located in the INL, are derived from neuroectodermal precursor cells called retinoblasts, which migrate to their proper location as they differentiate (Turner et al, 1990)..

"We take it day to day," the coach said. "Evalu