Dentate gyrus
The dentate gyrus is part of the hippocampus brain structure . It consists on the inside of the hilus , further outside the granular cell band ( stratum granulare ) and on the outside of the inner and outer molecular layer ( stratum molecularulare ). It is considered the entry point of the hippocampus.
Granule cell band
The granule cell band is the main component of the dentate gyrus in the hippocampus. The main type of cell is the ovoid granule cells , which have their dendrites in the inner and outer molecular layer and, in some cases, project glutamatergic gabaergic onto the pyramidal cells of the CA1 and CA3 region of the cornu ammonis , also in the hippocampus. They represent the entry point into the hippocampus, which receives its input from the entorhinal cortex . In one form of epilepsy , temporal lobe epilepsy , the granular cell ligament is often pathologically altered; then there is a broadening there, the cells diffuse apart and enlarge; one then also speaks of the “granule cell dispersion”. This phenomenon occurs due to the decreased secretion of reelin , a glycoprotein that is secreted by internal neurons and controls the stratification of the hippocampus. In the boundary layer between the hilus and the granular stratum , new neurons are formed, i.e. neurogenesis , even into adulthood. They arise close to the hilus and migrate into the grain cell band until they have integrated.
Molecular layer
The molecular layer is the part of the dentate gyrus in which the dendrites of the granular cells from the granular cell layer are located. It is divided into the inner and outer molecular layers. In the inner molecular layer the dendrites of commissural fibers of the mutual ( contralateral ) hippocampus are reached, in the outer one the fibers of the entorhinal cortex end. There are almost no cells in these two layers.
literature
- E. Forster, S. Zhao, M. Frotscher: Laminating the hippocampus . In: Nature Reviews Neuroscience . tape 7 , no. 4 , April 2006, p. 259-267 , PMID 16543914 (English).
Individual evidence
- ↑ Federative Committee on Anatomical Terminology (Ed.): Terminologia Anatomica . Thieme, Stuttgart 1998.