Figure 9.

BM disruption and altered radial glial end feet in the Zic1/3 double-mutant neocortex. A–H, Immunofluorescence staining for nestin (A, E) and laminin (B, F) in the dorsal cortical MZ of the Zic1^−/− (A–D) and Zic1/3 mutant (E–H) mice at E17.5. Sections were costained with DAPI (C, G). D and H are merged images of A–C and E–G, respectively. In the control Zic1^−/− brain, radial glia showed a parallel arrangement of fibers that terminated in well defined end feet at the pial surface (A). In the Zic1/3 mutants, absence of the nestin-immunoreactive radial glial end feet (asterisks in E) was associated with breakdown of the surface laminin (asterisks in F) and neuronal ectopias (arrowheads in G). In the mutant brains, the radial glial end feet were occasionally found to be detached from the pial surface in the regions of the ectopias. These defects were seen scattered throughout the cortical MZ. I, M, Immunofluorescence staining for nestin in the dorsal cortex of the wild-type (I) and Zic1/3 (M) mice at E17.5. The sections were counterstained with DAPI (blue). The locations of the neuronal ectopias are shown in white arrowheads, and the thinner continuous band of nestin-positive radial glial end feet is indicated by asterisks in M. The locations indicated in J–L and N–P are indicated by white brackets in I and M, respectively. J–L, N–P, Higher magnification of the indicated areas in I and M. Immunofluorescence staining for nestin (J, N) and laminin (K, O) in the wild-type (J–L) and Zic1/3 mutant (N–P) mice. L and P are merged images of J,K and N,O, respectively. The sections were counterstained with DAPI (blue). The thinner continuous band of nestin-positive radial glial end feet in the Zic1/3 mutants is indicated by a dashed line in N.