This statement is true. Developing countries indeed tend to have more people in urban areas than rural areas. For example, New York City has the massive population in the state of New York, compared to its rural areas upstate.
They are thus known as the "supporting cells" of the nervous system. The four main functions of glial cells are: to surround neurons and hold them in place, to supply nutrients and oxygen to neurons, to insulate one neuron from another, and to destroy and remove the carcasses of dead neurons (clean up).
