The Bulk Separation of Neuroglia and Neuron Perikarya

Abstract

Morphological studies of the central nervous system reveal an incredibly complex meshwork of neuronal and glial somata, axons, dendrites and glial processes, myelin and capillaries. It is apparent that biochemical studies of this tissue reflect the sum of the individual properties of each separate cell type. Yet we know that neurons, astrocytes, Oligodendroglia, microglia, and the other cells composing the brain have quite different functions and quite different biochemical properties. Even specialized regions of a single cell, for example, the dendritic tree, neuron perikaryon and axon, have their own particular ultrastructure, function, and complement of subcellular organelles; and therefore most probably have a unique composition and chemistry. Over the years many efforts have been made to resolve this complex tissue and determine the contribution made by each separate component to the biochemistry of the brain. It is beyond the scope of this chapter to discuss all the approaches, but they include microscopical histochemistry, quantitative histochemistry of different cortical layers and brain regions, microchemistry of hand-dissected cells, macrochemistry of grossly separated areas, studies of tumors, tissue culture of pure cell lines, and subcellular fractionation of constituents known to arise from a particular cell such as synaptosomes, myelin, and neuronal and glial nuclei.