A network of blood vessels and tissue that is made up of closely spaced cells and helps keep harmful substances from reaching the brain. The blood-brain barrier lets some substances, such as water, oxygen, carbon dioxide, and general anesthetics, pass into the brain. It also keeps out bacteria and other substances, such as many anticancer drugs. Also called BBB.
Last updated: 2014-02-26
Source: The National Cancer Institute's Dictionary of Cancer Terms (http://www.cancer.gov/dictionary)