Date of Award

8-1-1967

Document Type

Thesis

Degree Name

Master of Science (MS)

Department

Biology

Abstract

Since a basement membrane is present on all blood vessels and also on all tissues of ectodermal origin, the blood vessels of the central nervous system should have two basement membranes, one related to the blood vessel, the other related to the nervous tissue. Also, the tissue space usually bordering on the basement membranes should in the central nervous system separate the two. In the adult brain and spinal cord, however, only one basement membrane and no tissue space surround the blood vessels of the central nervous system. This study, therefore, has been concerned with the embryonic development of blood vessels of the central nervous system and the manner in which the single basement membrane - no tissue space relationship of blood vessels and nervous tissues is produced.

Twenty-seven chick embryos (48 hours to 5 days incubation) were serial sectioned at 2-4p and stained by the periodic acid-Schiff (PAS) technique. PAS positive basement membranes were demonstrated for light microscopy with this technique.

Blood vessels are formed in the mesenchyme surrounding the central nervous system. The early blood vessels lack a basement membrane. When the vessels invade the tissues of the central nervous system, the basement membrane of the central nervous system invaginates to form a membrane for the vessel and becomes applied directly to the surface of the vessel. The invaginated central nervous basement membrane remains continuous with the basement membrane on the surface of the central nervous system. Present techniques cannot Indicate whether additions to the invaginated basement membrane are made by the endothelial cells of the vessels.

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