Brain cells. Fluorescence light micrograph of a section through brain tissue, showing numerous glial cells and neurons (nerve cells). Glial cells, or neuroglia, are non-neural cells of the central nervous system (CNS, brain and spinal cord). They are the predominant cell type in brain tissue and are thought to outnumber neurons by 10 to 1. Their precise roles remain to be well understood. Glial cells provide physical and functional support to neurons and participate in maintenance of the blood-brain barrier by attachments to blood vessels (as seen here).