Fig. 3.

Effect of developmental synaptogenesis on CF mono- or multi-innervation during reinnervation in the mature system. (A) Micrograph showing an isochronic coculture of cerebellar plates with an age-matched whole explant expressing GFP, after immunolabeling for CaBP (red) and GFP (green). (B) Higher magnification of a coculture of a cerebellar plate with an age-matched explant, after immunolabeling for GFP (green, Bi and Bii) and CaBP (red, Biii) and revelation of biocytin (blue, Bii and Biii). Recorded PCs filled with biocytin were near the edge of contact (Bii and Biii). (C) Confocal sections showing higher magnification of GFP-positive fibers (green, Ci and Cii) establishing contacts (arrowheads) with PCs (asterisks, red, Cii) near the edge of contact. (D and E) Examples of CF-EPSCs recorded in a non-naive PC (D) and a naive PC (E) after 5 and 8 DPC, respectively. The non-naive PC displays a single-step CF-EPSC, suggesting CF mono-innervation; whereas the naive PC displays several CF-EPSC steps, suggesting CF multi-innervation. Holding potential was −80 mV. (F) Histogram showing the percentage of naive and non-naive PCs displaying from one to four or more CF-EPSCs steps. (Scale bars: A, 1 mm; Bi–Biii, 200 μm; Ci and Cii, 20 μm.)