One of the first things that most designers forget about CSS descendant selectors is that they are flexible. When CSS defines a descendant, it doesn't care whether the tag in question is the direct child, the grandchild, or some great-great-great-descendant of the initial element.
From the retina, visual information passes onto the bipolar cells and then to the optic nerve's ganglion cells. The optic nerve, which begins at the retina, is the sole visual pathway to the brain. Light information is conveyed as an electrical action potential through the neurons.
In general, neurons receive information either at their dendrites or cell bodies. The axon of a nerve cell is, in general, responsible for transmitting information over a relatively long distance. Therefore, most neural pathways are made up of axons. If the axons have myelin sheaths, then the pathway appears bright white because myelin is primarily lipid.