Fig. 4. The chemokine SDF1 and its receptor CXCR4 were expressed in complementary patterns in the developing hippocampus. Schematic representation of the migratory events ongoing at E14.5 and P0 (A,B). Red square shows enlarged area, migrating cells are in blue. Non-radioactive in situ hybridization for SDF1 (C,D) and CXCR4 (E,F) in E14.5 (C,E) and P0 (D,F) wild-type mouse tissue. (C,E) At E14.5, SDF1 (C) was expressed in the meninges, superficially in the cortex and within the developing dentate anlage (arrowhead). At the same age, CXCR-4 (E) was expressed in the dentate ventricular zone and in a continuum from the ventricular zone to the developing dentate (arrow). (D,F) At P0, SDF1 (D) was expressed primarily in the Cajal-Retzius cells that line the hippocampal fissure. CXCR4 (F) was expressed in the dentate migratory stream (arrow), starting above the fimbria and extending into the dentate gyrus. CXCR4 was also present in the forming granule cell layer. Scale bar in F: 250 µm for C-F.