Figure 6.
Developmental alterations in dendritic structure. (A) Measurements of apical dendrite length in various Sholl shells indicate that peak dendritic density for newborn GCs shifts outward from P17 (circles) to P70 (triangles). In both cases the majority of dendritic length is contained within the granule cell layer as indicated by the gray dashed lines [GC layer depth at P17: 68 ± 2 μm (n = 10) to P70: 90 ± 3 μm (n = 20)]. (B, C) Newborn granule cells at P70 exhibit both (B) greater TDL (n = 27 and n = 62 for P17 and P70, respectively) and (C) further reach than those at P17. (D) At P70, a greater proportion of the dendritic architecture of newborn neurons lies outside the GC layer. Bars represent the proportion of TDL beyond the average depth of the GCL layer. Asterisks indicate p < 0.0001.