Figure 5.

Loss of Cxcr4 from cells in the MZ causes premature migration into the cortical plate. A, B, A′, B′, Cxcr4-flox mice were bred with ubiquitous CreERT-expressing mice to generate mice carrying the CreERT transgene and Cxcr4-flox. The control mice are Cxcr4^flox/+, and the experimental mice are Cxcr4^flox/−. After administration of tamoxifen at E15.5, embryos are harvested the morning of delivery (E19.5) and analyzed by in situ hybridization for either Lhx6 (A, A′) or GAD67 (B, B′) to evaluate interneuron positioning. In the controls (CAGCreER^Tg/+; Cxcr4^flox/+), 4 d after tamoxifen many interneurons are still located in the MZ, whereas in experimental animals (CAGCreER^Tg/+; Cxcr4^flox/−), the MZ has essentially emptied of interneurons, and they have migrated radially into the cortical plate. The black arrows indicate the MZ. Scale bars, 100 μm.