Figure 1.

Confocal micrograph depicting the grid layout used to randomly select areas of the dentate gyrus in which newborn neurons were quantified. For each region of interest, we overlaid a series of numbered boxes. We then set the range of numbers in a random number generator and had it choose which grid numbers would be quantified at higher magnification. In this schema, the hilus and supra- and infrapyramidal blades of the granule cell layer (GCL) were quantified, in order to sample the entire dentate gyrus. Note that green portions of the grids are inclusion lines and red portions are exclusion lines. The grids along the GCL were positioned to include cells in the subgranular zone to the upper 3/5ths of the granule cell layer. The grids in the hilus were positioned to exclude cells in the subgranular zone, as DCX+ cells in this location are not necessarily hilar ectopic granule cells, and GFAP+ cells in this region typically display a morphology that is distinctly different than those in the hilus. It is pertinent to note that the apex and subjacent hilar areas are excluded from counting because cells in this region receive signals and cues from both the supra- and infrapyramidal blades of GCL. Scale bar = 100 µm.