Localization of calretinin in cells of layer I (Cajal-Retzius cells) of the developing cortex of the rat.

In order to be able to study the still disputed fate and function of the large Cajal-Retzius cells in the marginal zone (prospective layer I) during corticogenesis, it is necessary to have an unambiguous marker for them. We have found that antibodies to the calcium-binding protein calretinin label Cajal-Retzius cells in the rat throughout the whole period of corticogenesis into adulthood. Calretinin positive cells were also detected in the subplate, cortical plate and the ventricular zone. Transient expression of calretinin was observed in cells of the infragranular layers of the developing cortex. We conclude that calretinin can be used as a marker protein for Cajal-Retzius cells.