Movement Within the Brain of Ferritin Injected into the Cerebrospinal Fluid Compartments
It is appropriate at the outset of a symposium concerned with cerebral fluid compartments to examine the morphological evidence for and against the very occurrence of such compartments. Though preparative procedures are responsible for the large pericellular spaces within cerebral tissue visualized by light microscopy (Patek, 1944; Woolam & Millen, (1955), much smaller “gaps” of about 200 Å between all cells have been demonstrated electronmicroscopically. These intervals have been interpreted not as artifact but as representing the apposed lipid leaflets of adjacent cell membranes (Sjöstrand, 1958), or as the middle leaflets together with the fused outer leaflets of contiguous unit membranes (Schultz & Karlsson, 1965). According to either interpretation, there is no appreciable intercellular space except that of the synaptic cleft and other specialized junctions (Schultz & Karlsson, 1965). This view was supported by the observation that, following hydration of the brain, the 200 Å-wide interval remains constant while the glial cells become greatly distended. The excess water is envisioned as having moved from one cell directly into a neighboring cell across their contiguous plasmalemmas; the water so remains within the intracellular compartment (Gerschenfeld, Wald & Zadunaisky, 1959). However, the penetration of ferrocyanide into the 200 Å-wide gaps of the toad’s retina (Lasansky & Wald, 1964) and of ferritin into the Schwann cell channels in the toad’s spinal ganglion (Rosenbluth & Wissig, 1964) support Robertson’s conclusion (1957) that these gaps are open, hydrated channels.
KeywordsSynaptic Vesicle Synaptic Cleft Ependymal Cell Pinocytotic Vesicle Wide Cleft
Unable to display preview. Download preview PDF.
- Curtis, A. S. G.: Personal communication (1965).Google Scholar
- Diezel, P. B.: Iron in the brain: A chemical and histochemical examination, in: Biochemistry of the developing nervous system (ed. by H. Waelsch), New York: Academic Press, pp. 145–152 (1955).Google Scholar
- Lasansky, A. and F. J. Wald: The extracellular space in the toad retina as defined by the distribution of ferrocyanide, A light and electron microscope study, 15: 3, 463–480 (1963).Google Scholar
- Patek, P.: The perivascular spaces of the mammalian brain, Anat. Rec.. 88. 1–24 (1944).Google Scholar
- Sjöstrand, F. S.: Ultrastructure of retinal rod synapses of the guinea pig eye as revealed by three-dimensional reconstructions from serial sections, Ibid., 2, 122–170 (1958).Google Scholar
- Van Der Loos, H.: Fine structure of synapses in the cerebral cortex, Ibid., 60, 815–825 (1963).Google Scholar
- Woolam, D.H.M. and J.W. Millen: The perivascular spaces of the mammalian central nrvous system and their relation to the perineuronal and subarachnoid spaces, J. Anat., 89, 193–200Google Scholar