Cortical layer I changes in schizophrenia: a marker for impaired brain development?

The prefrontal cortices of healthy control subjects and schizophrenic patients were examined with an antibody mixture against non-phosphorylated neurofilaments (SMI 311). SMI 311 immunoreactivity was observed in numerous pyramidal neurons of layers II to VI and in Cajal-Retzius cells (CRC) of layer I. On the basis of their Golgi-like immunostaining, CRC could be classified into three morphologically heterogeneous groups, which showed different distributions in the two proband groups. The overall density of CRC in layer I did not differ significantly between controls and schizophrenics. However, CRC were more numerous in the lower third of layer I in schizophrenics and in the upper and middle third of layer I in controls. CRC play a key role in neuronal migration, thus, our results support the neurodevelopmental hypotheses of schizophrenic pathophysiology.