Positron beams for solids and surfaces

The extracellular matrix of brain is largely composed of aggregates formed by assembly of many proteoglycan and link protein molecules along a hyaluronan polymer backbone. Some cell types construct large, highly hydrated, pericellular matrices or 'coats' from these hyaluronan-mediated aggregates. We show here that embryonic glial cells produce such hyaluronan-dependent pericellular matrices in response to addition of serum or basic fibroblast growth factor plus transforming growth factor-beta. It is proposed that such a matrix is a significant component of the extracellular milieu of the brain, especially during morphogenesis within the developing brain, and that basic fibroblast growth factor and transforming growth factor-beta regulate its production.