Fig. 6

gata1:GFP granule cells project commissural axons into the crista cerebellaris. (A) Optical section of the cerebellum of 8 dpf gata1:GFP transgenic larvae. Note the dorsoposterior projection out of the cerebellum (blue arrow). Sagittal sectioning of 4-week-old gata1:GFP cerebella, immunohistochemistry against GFP-expression (B′) and counterstaining with Bodipy 630/650-X (B″) reveal positioning of these projections within the crista cerebellaris (B–B″, blue arrow). (C–K) 3-D time-lapse analysis (dorsal view) to characterize axonal projections into the crista cerebellaris (60 μm stacks of 21 individual images spaced 3 μm were recorded every 12 min). Brightest point projections of images of individual time-points are displayed. Individual axons are marked with arrows; note the contact and avoidance of growing axons from opposite cerebellar halves close to the dorsal midline (E, F, yellow circle; see slow motion sequence at the end of Movie 1). Around 65 hpf first projections into the forming crista cerebellaris can be observed (see green arrows in Movie 1 in supplementary material). Abbr.: cb, cerebellum; CC, crista cerebellaris; CL, caudal lobe; IGL, internal granule cell layer; MHB, midbrain–hindbrain boundary; ML, molecular layer; ot, optic tectum; rh, rhombencephalon; URL, upper rhombic lip.