The plasma membrane of bulk-isolated mature spinal neurons.

Large neuronal perikarya isolated in bulk fractions from adult bovine ventral spinal cord and examined by electron microscopy have discontinuities in their plasma membrane. A systematic investigation of the possible causes of the membrane defects indicates that the act of mechanical dissociation of the neurons from the spinal tissue is chiefly responsible for the changes. One likely cause of membrane loss is the avulsion of postsynaptic membrane along with the presynaptic elements, leaving bouton-free cell bodies with many gaps in their plasma membrane. Membrane defects were also demonstrated by the entry of procion yellow into the isolated perikarya. Other studies29 on these neuronal cell bodies have also shown that many soluble proteins can leave the neurons under some, but not all, conditions of isolation. These findings are discussed in relation to the possibilities of tissue culture of mature neurons and future research on bulk-isolated mature neurons.