What structure is highly vascularized an closely adheres to the surface of the brain?

The structure that is highly vascularized and closely adheres to the surface of the brain is the pia mater. It is the innermost layer of the meninges, which are the protective membranes covering the brain and spinal cord. The pia mater contains numerous blood vessels that supply nutrients and oxygen to the brain, and it closely follows the contours of the brain's surface, dipping into its sulci and fissures.