Figure 5.

eYFP-labeled MCs in the hilus of the dorsal DG provide strong commissural projections to the contralateral dentate, but the projections shift positions and become more diffusely organized as they extend ventrally as commissural and associational fibers. A, In a coronal section at 600 µm further caudal than the section in Figure 4, commissural projections from dorsal MCs in the hilus (H) remain stronger on the contralateral side (arrow), near the unlabeled granule cell layer (G), than on the transfected side, and increased diffuse labeling (*) is evident in the molecular layer (M). Dashed lines delineate the borders of the molecular layer in all panels. B, In a horizontal section at an anterior ventral level, beyond the level of labeled cell bodies, the axonal projections (arrows) expand and become more diffuse bilaterally. C, In a horizontal section at a more ventral level, the MC projections (arrows) form a narrower but distinct band in the molecular layer on each side. Scale bars: 200 µm (A–C).