Fig. 1. Disrupted formation of the EGL and the parallel fibers in Pax6 mutant (rSey²/rSey²) cerebella. (A,B) HE-stained cross-sections of E21 cerebella. The wild-type EGL (A) is subdivided in the outer germinal layer (g) and the inner premigratory layer (m). Spindle-shaped cells (arrows) in the premigratory layer are presumably migrating along the young parallel fibers. Pax6 mutant EGL (B) is thicker and uniform accumulation of round cells is observed. (C,D) DiI-labeled parallel fibers. Horizontal beams of parallel fibers in the deep EGL of the wild-type cerebellum (C) are not formed in the Pax6 mutant (D). Pial surface of the cerebella is indicated by asterisks. (E,F) Expression of TAG-1 in E21 cerebella. TAG-1 signal delineates the boundary between the EGL and the molecular layer in the wild-type cerebellum (E). TAG-1 is diffusely expressed throughout the EGL in the Pax6 mutant cerebellum (F). Some background autofluorescence can be observed in the vascular cells on the pial surface of the EGL. Scale bars: 25 µm in A-D; 40 µm in E,F.