Distal infrapyramidal and longitudinal mossy fibers at a midtemporal hippocampal level.
Timm's and horseradish peroxidase histochemical methods were used to demonstrate a small, distal infrapyramidal mossy fiber projection at midtemporal hippocampal levels in the rat. The Timm's sulfide silver method revealed sparse granules of dark, mossy fiber-like staining at an infrapyramidal location in an area roughly equivalent to hippocampal subfield CA3a (close to the CA1 border). The use of anterograde transport of horseradish peroxidase enabled the visualization of short mossy fiber axons that left the suprapyramidal bundle, penetrated the pyramidal cell layer, and terminated in a distal infrapyramidal position. The HRP-labeled axons possessed periodic swellings that are characteristic of mossy fiber morphology. The HRP studies also provided evidence for longitudinally oriented mossy fibers at midtemporal hippocampal levels. The distal tip of the suprapyramidal band of mossy fibers turned temporally and could be detected up to 1140 micrometers ventral to the main suprapyramidal band.
D000818:Animals; D006624:Hippocampus / Q000033:anatomy & histology*; D009412:Nerve Fibers; D051381:Rats; D011919:Rats, Inbred Strains; D013194:Staining and Labeling / Q000379:methods