Cajal-Retzius cell density as marker of type of focal cortical dysplasia.

Cajal-Retzius cells, identified using calretinin antiserum, were studied in layer I (LI) of adult human temporal cortex from epileptic patients with Taylor's focal cortical dysplasia and architectural dysplasia, in comparison with normal cortex. Both types of dysplasia showed LI hypercellularity, but only in architectural dysplasia was the density of Cajal-Retzius cells significantly increased. A subset of Cajal-Retzius cells were reelin immunoreactive, but none were GABA positive. These findings suggest that differences in the persistence of Cajal-Retzius cells, which probably reflect different types of alteration during brain development, can assist in characterizing different forms of cortical dysplasia.