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Neural stem cells differentiating to astrocytes (green) and sites of growth hormone receptor shown in red. There are two basic types of stem cell: adult stem cells, which are limited in their ability to differentiate, and embryonic stem cells (ESCs), which are pluripotent and have the capability of differentiating into any cell type.
Most of these adult neural stem cells lie dormant in the adult, but in response to certain signals, these dormant cells, or B cells, go through a series of stages, first producing proliferating cells, or C cells. The C cells then produce neuroblasts, or A cells, that will become neurons. [16]
Adult neurogenesis is the process in which neurons are generated from neural stem cells in the adult. This process differs from prenatal neurogenesis . In most mammals, new neurons are born throughout adulthood in two regions of the brain: [ 3 ]
A stem cell possesses two properties: . Self-renewal is the ability to go through numerous cycles of cell division while still maintaining its undifferentiated state. Stem cells can replicate several times and can result in the formation of two stem cells, one stem cell more differentiated than the other, or two differentiated cells.
Neurogenesis is the process by which neurons are generated from neural stem cells and progenitor cells. Neurons are 'post-mitotic', meaning that they will never divide again for the lifetime of the organism. [11] Epigenetic modifications play a key role in regulating gene expression in differentiating neural stem cells and are critical for cell ...
Pluripotent adult stem cells are rare and generally small in number, but they can be found in umbilical cord blood and other tissues. [48] Bone marrow is a rich source of adult stem cells, [49] which have been used in treating several conditions including liver cirrhosis, [50] chronic limb ischemia [51] and endstage heart failure. [52]
Neural stem cell niches are divided in two : the Subependymal zone (SEZ) and the Subgranular zone (SGZ). The SEZ is a thin area beneath the ependymal cell layer that contains three types of neural stem cells : infrequently dividing neural stem cells (NSCs), rapidly dividing transit amplifying precursors (TaPs) and neuroblasts (NBs).
It harbors the largest population of proliferating cells in the adult brain of rodents, monkeys and humans. [12] In 2010, it was shown that the balance between neural stem cells and neural progenitor cells (NPCs) is maintained by an interaction between the epidermal growth factor receptor signaling pathway and the Notch signaling pathway. [13]