This is an image of an adult zebrafish brain. The network of red lines outlining the shape of the brain (1) represents the densely packed blood vessels that span the exterior of the brain. The small ...

The total use of blood grows annually, as does the difficulty of procur ... Packed Red Blood Cells. Author: Hugh Chaplin, Jr., M.D. Author Info & Affiliations. Published August 14, 1969. ...

They consist of small, closely packed blood vessels. They may be absent at birth and develop during the first several weeks afterward. They usually grow rapidly, remain a fixed size, and then subside.