Figure 6.

The serial z-slice sections obtained by the tomography analysis showing the postsynaptic dendrite and spine in Figure 3M. We picked up 16 z-slice sections (A–R) of good quality from the middle of the z-slice sequence. The estimated thickness of the z-slice section is 1.75 nm. The Intermediately electron dense flocculate substance presumably synaptic cleft structure [for example; asterisks in image (C)] emerges continuously from the location where most synaptic boutons were found in the previous ultrathin section. Highly electron dense flocculate substance [for example; arrows in (C, I, O)], PSD, emerged at the edge of the intermediate one [arrows in (C)]. It gradually took over the domain of the intermediate electron dense flocculate substance (A–R).