Which cells are known for forming the blood-brain barrier?

Astrocytes are critical cells in the formation and maintenance of the blood-brain barrier (BBB). They are a type of glial cell in the central nervous system and play a key role in regulating the environment of neurons. Astrocytes have end-feet that envelop blood vessels in the brain, facilitating the communication between the vascular system and the brain tissue. This structural support is essential for the integrity of the blood-brain barrier, which functions to selectively allow certain substances to pass from the bloodstream into the brain while keeping harmful substances out.

In addition to their structural role, astrocytes also contribute to the biochemical processes that maintain the barrier's selectivity, such as the expression of specific transporters and junctional proteins. This is crucial for protecting the brain from toxins and pathogens while also regulating the passage of necessary nutrients, thereby maintaining homeostasis within the central nervous system.

Understanding the role of astrocytes in the blood-brain barrier is fundamental in neuroscience, especially concerning conditions that affect the barrier's integrity and related pathologies.