Figure 1.
Extent of the mossy fiber sprouting in the dentate gyrus of control, lesion-only, and lesioned, grafted animals. A1, An example of the intact control hippocampus. A2 is an enlarged view of the upper blade of the dentate gyrus from A1 and demonstrates the absence of aberrant mossy fiber sprouting in the DSGL (black asterisks). B1, An example of the lesion-only hippocampus at 12 months after injury. B2–B4 are regions of the upper blade, the crest, and the lower blade of the dentate gyrus from B1 and demonstrate very robust aberrant mossy fiber sprouting into the DSGL (white asterisks). C1, An example of the lesioned hippocampus receiving CA3 cell grafts at 4 d after injury and analyzed at 1 year after grafting. The transplant (boundaries depicted by interrupted lines) is located in the CA3 region. C2–C4 are regions from the upper blade, the crest, and the lower blade of the dentate gyrus from C1 and show minimal aberrant mossy fiber sprouting into the DSGL (black asterisks). C5 illustrates the innervation of the transplant by host mossy fibers. C6 is an enlarged view of the boxed region of the transplant in C5 showing clusters of CA3 pyramidal neurons surrounded by mossy fiber terminals. D1, An example of the lesioned hippocampus receiving CA1 cell grafts at 4 d after injury and analyzed at 1 year after grafting. The graft (boundaries depicted by interrupted lines) is located in the CA3 region. D2–D4 are regions from the upper blade, the crest, and the lower blade of the dentate gyrus from D1 and show robust mossy fiber sprouting into the DSGL (white asterisks). D5 and D6 (enlarged view of the boxed region in D5) illustrate the absence of mossy fibers in regions of the CA1 transplant. E1, An example of the lesioned hippocampus receiving CA3 cell grafts at 45 d after injury and analyzed at 1 year after grafting. The graft (the boundaries depicted by interrupted lines) is located just below the CA3 region. E2–E4 are regions from the upper blade, the crest, and the lower blade of the dentate gyrus from E1 and demonstrate minimal aberrant mossy fiber sprouting into the DSGL (black asterisks). E5 shows the innervation of graft areas by host mossy fibers. E6 is an enlarged view of the boxed region in E5 showing clusters of CA3 pyramidal neurons surrounded by dense mossy fiber terminals. DH, Dentate hilus; GCL, granule cell layer; MFB, mossy fiber bundle; T, transplant. Scale bars: A1, B1, C1, D1, E1, 500 μm; A2, (in B4) B2–B4, (in C4) C2–C4, C6, (in D4) D2–D4, D6, (in E4) E2–E4, E6, 100 μm; C5, D5, E5, 200 μm.