Ultrastructural changes in the edematous central nervous system. 3. Edema in shark brain.

Abstract

IN THE course of our electron microscopic investigation of various types of experimental edemas of the brain, 1,2 the complexity of the central nervous system (CNS) of mammals and the variety of its cells became a limiting factor in evaluating the significance of some of the observations. It was felt that a primitive brain, yet, a brain that contained all the essential structural elements of the nervous system of mammals, namely, nerve cells, glia cells, myelin sheaths, and an intracerebral network of blood vessels, would lend itself very well to studying edema formation in a relatively simple system. The criteria imposed by us excluded the use of invertebrates or such primitive vertebrates as cyclostomata because of the dissimilarity of their blood supply to the CNS and the lack of myelin sheaths. 3,4 This latter structure was essential to the study of cerebral edema because most forms of brain swelling are