HETEROGENEITY OF BRAIN FRACTIONS CONTAINING NEURONAL AND GLIAL CELLS¹

Abstract

Abstract— A density‐gradient procedure, previously reported to enable the separation of intact metabolically active neuronal and glial cells, has been appraised in terms of cellular homogeneity and integrity. Morphological examination by light and electron microscopy of fractions prepared by this method demonstrated marked heterogeneity and a high degree of cellular damage. The ‘neuronally enriched’ fraction contained a large proportion of non‐neuronal tissue including fragmented capillaries and endothelial cells. The ‘glial‐enriched’ fraction contained numerous nerve‐endings and synaptic boutons. The distribution of protein, DNA, carbonic anhydrase, succinate dehydrogenase and lactate dehydrogenase was examined, but such data were difficult to interpret in view of the marked heterogeneity of the fractions. Particulate material from the fractions was capable of endogenous respiration which was stimulated by glucose or pyruvate to levels slightly lower than that found in slices of cerebral cortex. The limitations of this and other methods for separation of cell types from neural tissue are discussed.