Fig. 4.
Filament network at the PSD. (A) Meshwork of horizontal filaments at the core of the PSD. The shorter type (purple) is 4–5 nm in diameter and ≈20 nm long, and the longer type (white) is 5–6 nm in diameter and 30–35 nm long. The asterisks indicate sheet-like structures. (B and C) Shorter (B, arrow) and longer (C, arrowhead) types of horizontal filament in virtual sections. (Scale bar: 20 nm.) (D) Cross-sectional view of the PSD in A showing layering of horizontal filaments. The shorter filaments (B, purple) lie somewhat closer to the postsynaptic membrane than the longer filaments (C, white).