Fig. 6. Emx2^–/– and Wnt1-Tg mice exhibit diffuse abnormalities of the marginal zone and subplate at 18.5 dpc. (A-C) In situ hybridization analysis shows a reduction in the number of reelin-positive Cajal-Retzius (CR) cells in the anterior regions of the marginal zone and subplate of Emx2^–/– (B) and a patchy reduction in Wnt1-Tg (C) mice when compared with control wild-type littermates (A) at 18.5 dpc. Note, that scattered reelin-positive cells (arrowheads) with small cell morphology persisted at 18.5 dpc but few cells with clear CR type morphology were observed in anterior dorsolateral cortex. (D-F) Immunohistochemistry demonstrating a marked reduction in the number and complexity of calretinin-positive cells and CR cells (arrowheads), and their processes within the marginal zone and subplate of Emx2^–/– and Wnt1-Tg mice. cp, cortical plate proper (layers II-VI); mz, marginal zone (layer I); sp, subplate. Scale bar: 50 µm.