Fig. 7.

Serial electron micrographs showing aberrant CF jumping that causes multiple innervation in the GluRδ2 knock-out mouse. A–H are taken from levels indicated in reconstructed image N. To show synaptic contacts of the labeled CF with dendrites D1–D4,boxed regions in A–H are enlarged and provided with adjacent images as I1, I2, J1, J2, K1–K3, L1–L3, and M1–M3. The arrow inI2 indicates elongated postsynaptic density exceeding over a synaptic junction between the CF terminal and spineS1. Note unlabeled CFs, uCF1(L1–L3) and uCF2(M1–M3), both of which form large terminal swellings with densely packed vesicles and ascend along the D2 orD3 dendrite, respectively. uCF1 anduCF2 form asymmetrical synapses with spineS6 or spines S7 and S8, respectively. Scale bars, 1 μm. (Figure 7 continues.)