Ultrastructural features of biopsied temporopolar cortex (area 38) in a case of schizophrenia.

An electron microscopic study of tissue from area 38 of the temporopolar cortex obtained at surgery from a schizophrenic patient has established that, although the ultrastructure of this area was in general similar to that found in normal human cerebral cortex, the neuropil contained many unusual asymmetrical synapses. Their synaptic vesicles were clumped, often away from the synaptic thickenings, and the thickenings themselves were short, compared to the total length of apposed pre- and postsynaptic membranes. Some preterminals were unusual in that they were myelinated. The affected terminals were always of the asymmetrical variety, and therefore probably excitatory. Glutamate is likely to be the transmitter at, at least, some of these synapses. The clumped, but numerous, synaptic vesicles, together with short synaptic active zones, is consistent with previous observations of normal glutamate levels in schizophrenic brain, but reduced numbers of glutamate receptors in some cortical areas.