THE RETICULAR PERIVASCULAR TISSUE OF THE CENTRAL NERVOUS SYSTEM

Abstract

Long''s stain (1948) for reticular and collagenous fibers was modified and applied to central nervous system material from rats previously injected with colloidal C into the subarachnoid space daily for 3 weeks from birth to sacrifice. Human post-operative material from patients dying from poliomyelitis and epidemic encephalitis were similarly stained. The outer layer of the perivascular sheath is continuous with the pia mater and the inner layer with the arachnoid. Reticular tissue surrounds all cerebral blood vessels except, possibly, the capillaries. The true perivascular (Virchow-Robin) spaces can be distinguished from artefact perivascular spaces. The former contain perivascular exudates in pathological material and there is suggestion of a responsive fibrosis.