The Discovery of Adult Mammalian Neurogenesis
Altman Anat Rec 1963.pdf
The arrow indicates a labeled hippocampal granule cell in a young adult rat that was injected two times intraperitoneally with 3H-thymidine at 4 months (one week interval between injections) and survived to 5 months (counterstained autoradiogram). This is Figure 13 in the above paper and is the first illustration (among others in the paper) of a hippocampal neuron generated during the adult period.
INFORMATION ADDED OCTOBER, 2014: A brief communication from our laboratory documents the histological evidence for a subgranular zone in the dentate gyrus of children aged 1 month to 6 years. This finding supports the hypothesis that the dentate granular layer in humans has the same developmental pattern as in other mammals.
BRIEF COMMUNICATiON 1: HIPPOCAMPAL POSTNATAL NEUROGENESIS IN CHILDREN
Neurons in the Rat Dentate Gyrus Granular Layer Substantially Increase During Juvenile and Adult Life
These data are volumetric granule cell nuclei throughout the entire hippocampus in rats ages 30, 120, 200, and 365 days. The important finding is thzt the granule cell population substantially increases its numbers with age. The adult-generated neurons are adding to the population.
Changes in the Total Number of Dentate Granule Cells in Juvenile and Adult Rats A Correlated Volumetric and 3H·Thymidine Autoradiographic Study*
These figures show that the dispersed germinal matrix in the adult dentate gyrus is a fragmentary scattering of small, dark cells in the dentate hilus (*, Fig. 3) called the subgranular zone (Altman and Bayer, 1975, see below).
Initially, 3H-thymadine is picked up by precursor cells in the subgranular zone during the S-phase of the cell cycle. Some progeny become neurons that differentiate into mature granule cells. The graph in figure 4 shows that when animals survive longer after injections, there is a higher proportion of labeled mature granule cells(black bars) compared to immature cells (clear bars). See also fig. 5 in Altman&Das JCN 1965.pdf
Figure 2 in Altman&Bayer hippo dev 1975.pdf shows the heavy 3H-thymidine label uptake by presumptive granule cell precursors in the dispersed subgranular zone in the hilus (HI) of the dentate gyrus. As rats mature, the subgranular zone is scattered small cells at the junction between the base of the granule cell layer and the hilus (Fig. 3 center). Many of the postnatally-generated and all of the adult-generated dentate granule cells arise in the subgranular zone. (AH, Ammon’s horn; GL, dentate granular layer; MO, dentate molecular layer)
Links to Papers:
Are New Neurons Formed in the Brains of Adult Mammals?
Autoradiographic Investigation of Cell Proliferation in the Brains of Rats and Cats
Autoradiographic and Histological Evidence of Postnatal Hippocampal Neurogenesis in Rats 1
Postnatal Development of the Hippocampal Dentate Gyrus Under Normal and Experimental Conditions
