This medical illustration depicts the anatomy and cellular organization of the Blood-Brain Barrier (BBB) and the Neurovascular Unit (NVU). The primary figure shows a sagittal view of the human brain, with an inset focusing on a microscopic cross-section of a brain capillary. The capillary is lined by endothelial cells containing tight junctions, which serve as a restrictive physical barrier between the vessel lumen and the brain parenchyma. Surrounding the endothelial layer is a basement membrane and closely associated pericytes. The entire vessel structure is unsheathed by astrocytic end-feet, which facilitate metabolic support and barrier maintenance. A neuron is also shown with its terminals in close proximity to the astrocytic end-feet, illustrating the functional coupling between neural activity and blood flow within the NVU. This diagram is designed for intermediate to advanced neurobiology or pharmacology education, highlighting the structural basis of central nervous system homeostasis and selective permeability.

An anatomical diagram illustrating the components of the neurovascular unit (NVU) within the central nervous system. The central focus is a brain capillary formed by brain microvascular endothelial cells (BMECs), shown as a pink cylindrical structure with red blood cells visible in the lumen. Branching pericytes are depicted adhering to the abluminal surface of the capillary. The vessel is almost entirely enveloped by astrocyte end-feet, represented as light-colored, broad expansions from star-shaped glial cells. In the background, a dense network of neuronal processes and other glial cells represents the brain parenchyma and extracellular matrix. This illustration highlights the structural relationship between the vascular system and the neural environment, demonstrating the basis of the blood-brain barrier (BBB) and the cooperative regulation of brain homeostasis through cellular interactions between neurons, astrocytes, pericytes, and endothelial cells.