ABSTRACT
In the vertebrate brain, two major classes of cells, glia and neurons, are generated from a proliferative zone that surrounds the central ventricular space. The newly generated cells migrate from the proliferative zone to their adult positions and extend processes. Neurons elaborate relatively long and complex axonal and dendritic processes that interconnect in highly stereotypedways to generate the circuitry of the mature brain. Glial cells also extend processes that enwrap neural and vascular elements. Once the complex circuitry of the central nervous system (CNS) has achieved its mature structure and connections, it becomes stabilized and is maintained throughout adulthood. Proteoglycans, a group of glycoproteins that are invested with covalently bound glycosaminoglycan (GAG) chains, are one of the important classes of molecules in brain development and maturation. Although the role of proteoglycans in other tissues, such as cartilages, was established long ago, an appreciation of their importance in the CNS has only been established relatively recently.
