Date of Award


Document Type


Degree Name

Master of Science (MS)




Blood vessels traversing the subarachnoid space possess morphological characteristics reflecting specialized function and environment. The spaces associated with these vessels are of special Interest. Until recently, however, clear descriptions of these vessels and the spaces associated with them were limited by Inadequate fixation. This study describes the normal morphology of blood vessels in the subarachnoid space and their associated spaces in tissues known to be fixed adequately for fine structure.

Thirty-eight young adult female rats were perfused with buffered aldehydes. Selected tissues were prepared for light microscopy with the least possible modification of standard procedures. Using common staining techniques, the blood vessels at the base of the brain, along with the Intact leptomenlnges, were studied by light microscopy.

Both arteries and veins possess unusually thin walls. Connective tissue components are sparse In all three coats. Arterial valve-like projections are present near major branches. Perivascular spaces between leptomenlngeal cellular extensions are not evident. The subarachnoid, intramural and perivascular spaces are not morphologically separate spaces. All are part of the general tissue space of the body.

The observed differences in vascular mural structure as well as in the associated spaces are understandable in relation to function, particularly when interpreted in terms of pressure differentials in their immediate surroundings. Morphologically, they represent variations of a master pattern of tissue organisation common to the body at large, variations that collate well with the physical circumstances and functional requirements of the special area which they serve.