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. Author manuscript; available in PMC: 2010 Dec 30.
Published in final edited form as: Annu Rev Psychol. 2010;61:111–C3. doi: 10.1146/annurev.psych.093008.100359

Figure 2.

Figure 2

Cell birth and cell death in the dentate gyrus across the lifespan. On postnatal day 1, granule neurons that were generated embryonically have begun to form the tip of the suprapyramidal blade of the granule cell layer (GCL). During the first postnatal week, the GCL continues to be formed from progenitor cells located within the hilus along four general gradients—caudal to rostral, suprapyramidal to infrapyramidal, suprapyramidal tip through crest to infrapyramidal tip, and superficial to deep. Thereafter, the production of new granule neurons tapers off but remains substantial in adulthood until animals reach middle age and become aged. Alongside neurogenesis, there is substantial death of granule neurons. Cell death peaks at the end of the first postnatal week as indicated by the presence of pyknotic (i.e., dying) cells. In adulthood, substantial cell death continues, especially of newborn neurons located primarily within the subgranular zone (SGZ) or deep within the GCL.