Neurogenesis in the adult hippocampus Free webcam girls ipot
Immunohistochemistry for Brd U can be combined with the detection of mature markers to identify the phenotype of the newborn cells.Recently, several molecular techniques for labeling adult-born cells have been developed, including transgenic mice with GFP driven by a stem cell gene's promoter (i.e., Nestin-GFP; Figure 2, top left) and retroviral labeling ( Figure 2, top right).The evidence for multipotency of NPCs in vivo remains scant.There are two neurogenic regions in the adult brain where under physiological conditions NPCs give rise to new neurons: (1) the subventricular zone of the lateral ventricles (SVZ) where NPCs generate cells that migrate into the olfactory bulb, and (2) the subgranular zone (SGZ) of the dentate gyrus (DG) where new granule cells become integrated into the local neuronal network ( Figure 1).NPCs are not limited to neurogenic regions of the brain, rather their proliferation can be observed in most CNS regions, especially after injury.However, in these other regions it appears that neurogenesis is actively repressed by the local environment - NPCs from non-neurogenic regions have been observed to give rise to neurons when transplanted into the hippocampus.Although they reside in the SGZ, they extend processes up into the molecular layer. In contrast “Type-2” cells (or ‘C’ cells in the SVZ),have a high proliferative activity but have a small roundish morphology.
The process appears more widespread but still limited in other vertebrate classes, having been described in select brain regions of certain birds, fish and reptiles.Two criteria are typically used to define a cell as a stem cell:1) the potential of self-renewal and 2) the ability to give rise to multiple distinct cell types.NPCs isolated from the adult brain are classified as a ‘’multipotent’’ cell because they can differentiate into the the three main lineage cell types of the nervous system (neurons, astrocytes, and oligodendrocytes) when cultured in vitro.One critical aspect of adult neurogenesis is the selection process.While large numbers of new neurons are born to the OB and DG, only a fraction of these cells survive.
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In contrast to adult neurogenesis in the dentate gyrus, cells that were born in the SVZ migrate a long distance into their target area, the olfactory bulb.