Fig. 3. Morphology of granule cells in vitro (A-D), in vivo (E-H) and glia (I,J). (A) Brightfield micrograph of wild type granule cells in a migration culture. Note the elongated cell profiles as granule cells migrate along glial fibers. The same culture following Tuj-1 immunohistochemistry is seen in B. (C) An equivalent migration culture with astrotactin null granule cells. Cell profiles are more rounded and are not as closely associated with the glial process. Tuj-1 stain of the same culture reveals that the rounded profiles are differentiated neurons. (E-J) Sagittal sections through cerebellum with EGL at top of figure. (E) Wild-type P6 Nissl stained section showing normal morphology of migrating granule cells in the molecular layer. Note that cells are ‘tear drop’ in shape (arrows). (F) Section showing the more rounded granule cells (arrows) in the molecular layer of P6 astrotactin null mice. (G) Nissl section of a P8 wild-type mouse with elongated migrating profiles in the molecular layer above the much larger Purkinje cells. (H) Section from an astrotactin null P8 mouse showing rounded granule cell profiles in the EGL (arrow). (I,J) Bergmann glia labeled with GFAP in normal and mutant mice. Scale bars: 30 µm.