FIG. 5.

Reduced outgrowth of mossy cell axons. By P14, calretinin-positive mossy cell axons had reached the inner molecular layer (Iml) of the granule cell layer (Gcl) in the nor-1^+/+ dentate gyrus (A), whereas only a weak calretinin staining could be seen in the nor-1^−/− mice (B). An even more obvious decrease in these calretinin-positive mossy cell axons was seen in the adult nor-1^−/− dentate gyrus (D). (F) Higher magnification of the suprapyramidal blade (Spb), which was almost devoid of calretinin-positive axons in the nor-1^−/− dentate gyrus. No difference was found between nor-1^+/+ and nor-1^−/− mice in the number of calretinin-positive mossy cell bodies in the hilus of the ventral hippocampus, where the majority of these cells are located (G and H), or in the commissural fibers that cross the midline at the level of the hippocampal commissure (I and J), indicating a specific reduction in mossy cell associational fibers in the nor-1^−/− mice. Bars, 100 μm (A to D and G to J) and 25 μm (E and F).