Figure 10.

Electron micrograph showing a perforate synapse (Sp1) corresponding with 3D image “T2 PE” shown in Figure 9C. A–L, Successive ultrathin sections of an entire spine head (Sp1) that was innervated by a VGLUT2-positive axon terminal. An asymmetrical synapse was observed, and the middle of the successive ultrathin sections postsynaptic junction was split in two parts (E–G) and again merged together, indicating a typical perforated synapse. A second synapse (Sp2) formed by the VGLUT2-positive axon terminal (onto different postsynaptic target) is also a perforated synapse because the postsynaptic density is split into two parts in J–L.