Subgranular zone

The subgranular zone (SGZ) is a layer of cells in the dentate gyrus, in the hippocampal formation, which is a site of adult neurogenesis in the brain.

Because astrocytes are in close contact with many of the other cells in the SGZ, they are well-suited to serve as sensory and regulatory channels in neurogenesis.

Blood vessels carry hormones and other molecules that act on the cells in the SGZ to regulate neurogenesis and angiogenesis.

Contrary to long-standing beliefs, neurogenesis in the SGZ occurs not only during prenatal development but throughout adult life in most mammals, including humans.

Wnt and bone morphogenic protein (BMP) signaling also are neurogenesis regulators, as well as classical neurotransmitters such as glutamate, GABA, dopamine, and serotonin.

Stressors such as sleep deprivation and psychosocial stress induce the release of glucocorticoids from the adrenal cortex into circulation, which inhibits neural cell proliferation, survival, and differentiation.

Other environmental factors such as physical exercise and continual learning can also have a positive effect on neurogenesis, stimulating cell proliferation despite increased levels of glucocorticoids in circulation.

For instance, the high rate of neurogenesis and neuronal turnover in young animals may be the reason behind their ability to rapidly acquire new memories and learn new tasks.

The subgranular zone (in rat brain). (A) Regions of the dentate gyrus: the hilus, subgranular zone (sgz), granule cell layer (GCL), and molecular layer (ML). Cells were stained for doublecortin (DCX), a protein expressed by neuronal precursor cells and immature neurons. (B) Closeup of subgranular zone, located between the hilus and GCL. From a paper by Charlotte A. Oomen, et al., 2009.
Structure and features of the neurogenic niche. Adapted from a paper by Ilias Kazanis, et al., 2008.