Longitudinally restricted axonal projections of hippocampal granule cells suggest that transverse segments of the granule cell layer may operate independently (the "lamellar" hypothesis). Longitudinal projections of excitatory hilar mossy cells could be viewed as antithetical to lamellar function, but only if longitudinal impulse flow effectively excites distant granule cells. We, therefore, de...

The dentate gyrus of the hippocampus is uniquely organized with a displaced proliferative zone that continues to generate dentate granule cells throughout life. We have analyzed the expression of Notch receptors, Notch ligands, and basic helix-loop-helix (bHLH) genes during dentate gyrus development to determine whether the need to maintain a pool of undifferentiated precursors is reflected in ...

Granule cells in the dentate gyrus of the hippocampus are thought to be essential to memory function by decorrelating overlapping input patterns (pattern separation). A second excitatory cell type in the dentate gyrus, the mossy cell, forms an intricate circuit with granule cells, CA3c pyramidal cells, and local interneurons, but the influence of mossy cells on dentate function is often overloo...

In vivo intracellular recording and labeling in kainate-induced epileptic rats was used to address questions about granule cell axon reorganization in temporal lobe epilepsy. Individually labeled granule cells were reconstructed three dimensionally and in their entirety. Compared with controls, granule cells in epileptic rats had longer average axon length per cell; the difference was significa...

To determine whether activation of the type 2 adrenal steroid receptor affects granule cell death in the developing dentate gyrus, we treated rat pups with the type 2 receptor agonist RU28362 and examined degenerating cells using terminal deoxynucleotidyl transferase (TdT)-mediated dUTP nick end labeling (TUNEL) and Nissl staining. RU28362 administration decreased the numbers of degenerating gr...

Dissociated cells prepared from the cerebellar primordia of normal 15-day mouse embryos were grafted into the cerebellum of 1-month-old weaver mutant mice which are characterized by degeneration of cerebellar granule cells during the early postnatal period. The growth of the grafted cells was investigated at 1 month after the operation. Implanted cells were highly developed to form a large mass...

Compound exocytosis is found in many cell types and is the major form of regulated secretion in acinar and mast cells. Its key characteristic is the homotypic fusion of secretory granules. These then secrete their combined output through a single fusion pore to the outside. The control of compound exocytosis remains poorly understood. Although soluble N-ethylmaleimide-sensitive factor attachmen...

Experimental mouse chimeras have proven useful in analyzing the cell lineages of various tissues. Here we use experimental mouse chimeras to study cell lineage of the hippocampus. We examined clonal architecture and lineage relationships of the hippocampal pyramidal cells, dentate granule cells, and GABAergic interneurons. We quantitatively analyzed like-genotype cohorts of these neuronal popul...

In humans, temporal lobe epilepsy (TLE) is often associated with Ammon's horn sclerosis (AHS) characterized by hippocampal cell death, gliosis and granule cell dispersion (GCD) in the dentate gyrus. Granule cells surviving TLE have been proposed to be hyperexcitable and to play an important role in seizure generation. However, it is unclear whether this applies to conditions of AHS. We studied ...

After experimental status epilepticus, many dentate granule cells born into the postseizure environment migrate aberrantly into the dentate hilus. Hilar ectopic granule cells (HEGCs) have also been found in persons with epilepsy. These cells exhibit a high rate of spontaneous activity, which may enhance seizure propagation. Electron microscopic studies indicated that HEGCs receive more recurren...