A new approach for determining the volume of cerebral extracellular fluid and demonstration of its communication with c.s.f

Abstract

SUMMARY1. A new technique is presented for determining the volume of extracellular space in bowfin (Amia calva) brain during in vitro incubation. It consists of solving simultaneous equations which are applied to determine the volume of extracellular space as well as intracellular marker concentration. This technique allows for a better insight into the redistribution of marker between incubation medium and extracellular space as well as between extracellular and intracellular space.2. Na+, K+ and Cl-equilibrated within 10-15 min between incubation medium and extracellular space. There was no evidence of a homoeostatic mechanism controlling the concentration of these ions in the extracellular fluid, which appeared to be in equilibrium with cerebrospinal fluid. The extracellular spaces of these ions were identical: Na+, 23-4; K+,

Supratentorial intracerebral epithelial (ependymal) cysts: review, case reports, and fine structure.

“…It is unlikely that cysts acting as expanding lesions originate from an outpouching of ependyma-lined ventricular wall. Markers of high molecular weight may pass through the intercellular clefts between ependymal cells (Brightman, 1965) and electrolytes in the CSF equilibrate rapidly with the extracellular compartment of the brain tissue (Friede and Hu, 1971). Furthermore, the tips of the occipital horns of the lateral ventricles commonly form small cysts having no communication with the body of the ventricle.…”

Diffusion in Brain Extracellular Space

“…All these compounds are uncharged, which may be an advantage given the fixed negative charges associated with the extracellular matrix. Fenstermacher and colleagues (104) concluded that mannitol was not entirely satisfactory while the molecular weight of inulin is not precisely defined and there is some evidence that this marker decomposes (108); later studies by Fenstermacher and colleagues settled on sucrose as the best marker. Even sucrose, however, may be sequestered over time by unidentified brain compartments (100, 118).…”