The perivascular spaces of ovine and canine brains

Abstract

The specialised histology and anatomy of the central nervous system (CNS) is reflected in its pathology. This is particularly so for the perivenular/periarterial spaces in which inflammatory cells accumulate in inflammation. These spaces, although structurally not lymphatics, act as lymphatics draining fluid from brain to subarachnoid space and to lymphatics draining to deep cervical lymph nodes. Inflammatory cells may enter or leave the CNS by this route. In immune-based inflammation, they are colonised by subsets of immune cells allowing the processing of antigen, synthesis of antibody and development of cell mediated immune reactions.