Fig. 2. Treatment of reeler slice cultures with recombinant reelin increases the length and density of GFAP-positive fibers. (A) Portion of the hilus of the dentate gyrus in an untreated control culture of reeler hippocampus. GFAP-positive cells have relatively thick, short processes, reminiscent of astrocytes. Two characteristic cells are labeled by arrows. (B) Portion of reeler dentate gyrus after incubation with recombinant reelin for 7 days. The length of GFAP-positive fibers has dramatically increased. The fibers run in all directions, often crossing each other at right angles (arrowheads). (C) Same control culture as that shown in A, counterstained for NeuN. As is characteristic for the migration defect in the reeler mutant, dentate granule cells are scattered all over the dentate gyrus (DG). (D) Same culture as that shown in B, counterstained for NeuN. Treatment with recombinant reelin, while increasing the length of GFAP-positive fibers, did not rescue the granule cell migration defect characteristic of the reeler dentate gyrus. CA3, hippocampal region CA3. Scale bars: 20 µm in A,B; 75 µm in C,D. (E,F) Incubation of the cultures with recombinant reelin significantly (^**) increased both the length and the density of GFAP-positive fibers in the hilar region of reeler cultures (n=10; P<0.01).