Fluid Environment of the Brain presents the proceedings of a symposium held in Bar Harbor, Maine in September 1974 under the joint sponsorship of the Mount Desert Island Biological Laboratory and the National Cancer Institute. Contributors discuss the fluid matrix of the brain and the functional relationships among neurons, neuroglia, and their extracellular fluids in normal and pathological states. They focus on the cerebral interstitial fluid and the membranes—or barrier mechanisms—which contribute to the regulation of the physical and chemical characteristics of these fluids. This book is organized into four sections encompassing 17 chapters and begins with an overview of anatomical relationships, with special reference to the morphology of the walls around fluid compartments in the nervous tissue. The reader is then introduced to the physiology of the blood-brain barrier and the choroid plexus, as well as the exchange between the cerebrospinal fluid (CSF) and brain. Methods for determining the permeability of the blood-brain barrier are described. The book also explores amino acid transport mechanisms in the choroid plexus, distribution of hormones by CSF, and the physiological aspects of lactate and peptides in the CSF. Special consideration is given to the attempts to use CSF as a means of studying the chemistry, metabolism, and possible endocrine functions of the brain. This book is of interest to pharmacologists and clinicians, as well as physiologists and neurochemists.