News FocusMysteries of Development

Why Do So Many Neurons Commit Suicide During Brain Development?

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Science  07 Jun 2013:
Vol. 340, Issue 6137, pp. 1157-1158
DOI: 10.1126/science.340.6137.1157

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Scientists have identified at least two, and possibly three, waves of neuronal cell death in the embryonic mammalian brain during development. Long gone are the days when researchers thought that neurotrophic hypothesis alone explained why so many cells die in the brain. The first wave strikes down cells before they are fully differentiated neurons. A second wave of cell suicide occurs after neurons have begun to differentiate and extend their axons to make contact with other cells. Although some researchers have tried to "shoehorn" the die-off at this later stage into the neurotrophic hypothesis. The developing nervous system might also compensate for the extra cells by simply not linking them in to neural circuits.