Figure 3.

Sprouting and elongation of PC collaterals. A–F, Phase-contrast light microscopic images of BDA-labeled PF trajectory in sham-operated control (A, D) and PF-transected mice on postlesion days 7 (B, E) and 30 (C, F) in wild-type (A–C) and GluD2-KO (D–F) genotypes. Arrowheads indicate varicosities or boutons along BDA-labeled PFs, while arrows indicate the branching point of PF collaterals. C, Inset, A different focal plane of the boxed region in the center, showing numerous varicosities along a long collateral of a BDA-labeled PF. G, Bar graphs showing the density of PF varicosities per mm of BDA-labeled PF (mean ± SD, n = 3 mice for each). No significant difference in density after PF lesioning was found in either wild-type (left) or GluD2-KO (right) mice. The density of PF varicosities, at ∼160/mm, is consistent with a previous study in the cat (Brand et al., 1976). Scale bars, 10 μm.