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dentate gyrus

One of the 2 interlocking gyri composing the hippocampus. The other is the cornu ammonis (Ammon horn). Structure: The dentate gyrus consists of 3 layers 1) molecular layer 2) granule cell layer a) granule cells b) basket (GABAeric) cells 3) hilus or polymorphic layer The principal cell layer of the dentate gyrus is the granule cell layer, with a prominant dendritic arborization (molecular layer). The granule cell & molecular layer are often referred to as the fascia dentata. The hilus of the dentate gyrus contains neuroblasts that form granule cells from birth into old age. Newly formed granule cells accumulate under the older granule cells gradually increasing the thickness of the granule layer throughout life The human dentate gyrus contains about 9 x 10E6 granule cells. Afferents: - entorhinal cortex (perforant pathway) Efferents: 1) cornu ammonis CA3 pyramidal cells (mossy fiber pathway) 2) cells of the of the dentate gyrus do not project outside of the hippocampal formation Local projections: 1) mossy cells of the hilus project to distant parts of the dentate gyrus terminating in the proximal 1/3 of the molecular layer 2) mossy fibers from granule cells synapse on mossy cells of the hilus as well as CA3 pyramidal cell dendrites 3) GABAergic cells in the hilus project to the distal 2/3 of the molecular layer close to the cells of origin Comparative biology: - neurogenesis continues throughout life in the subgranular zone of the dentate gyrus of the adult mammalian hippocampus - this appears not to be true for humans - in humans hippocampal neurogenesis ceases by age 13 [4] - ref [5] claims neurogenesis persists throughout aging* * if neurogenesis were to persist throughout aging from age 14-79 & newly formed granule cells were to accumulate under the older granule cells gradually increasing the thickness of the granule layer, volume of the dentate gyrus should increase throughout aging; ref [5] reports no change in dentate gyrus volume from age 14-79 * it is also noted the ref [4] reports that neurogenesis in the human hippocampus ceases by age 13

Related

cornus ammonis (Ammon's horn) dentate granule neuron entorhinal cortex (Brodmann's area 28) hippocampal mossy fiber pathway perforant pathway

General

gyrus

References

  1. Stedman's Medical Dictionary 27th ed, Williams & Wilkins, Baltimore, 1999
  2. The Human Nervous System, George Paxinos, Academic Press, San Diego CA 1990
  3. Wikipedia: Dentate gyrus https://en.wikipedia.org/wiki/Dentate_gyrus
  4. Sorrells SF, Paredes MF, Cebrian-Silla A Human hippocampal neurogenesis drops sharply in children to undetectable levels in adults. Nature. April 6, 2018. Published Online March 7, 2018 PMID: 29513649 https://www.nature.com/articles/nature25975
  5. Boldrini M, Fulmore CA, Tartt AN et al Human Hippocampal Neurogenesis Persists throughout Aging. Cell Stem Cell. April 5, 2018. 22(4):589 PMID: 29625071 https://www.cell.com/cell-stem-cell/fulltext/S1934-5909(18)30121-8

Component-of

hippocampus (hippocampal formation)

Components

cornus ammonis [CA]-4 (dentate hilus)

Images

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