Table 1.

Size and protein copy numbers of SSDs and PSDs obtained with different experimental techniques.

Structure	Diameter (nm)	Molecule numbers	Technique	Synapse type	References
SSD	50–130*		SMLM	Excitatory, hippocampal	MacGillavry et al. (2013), Nair et al. (2013), Broadhead et al. (2016), Chamma et al. (2016a,b) and Haas et al. (2018)
	130–760*		STED	Excitatory, hippocampal and cortical	Nair et al. (2013), Broadhead et al. (2016) and Hruska et al. (2018)
	~300*		SIM	Inhibitory, hippocampal	Crosby et al. (2019)
	70*	~20 AMPARs/SSD*	STORM	Excitatory, hippocampal	Nair et al. (2013)
PSD	300 (100–800)#		EM	Excitatory, hippocampal	Harris and Stevens (1989) and Bourne and Harris (2011)
	290 (110–650)#		EM	Excitatory, cortical	Arellano et al. (2007) and Santuy et al. (2018)
	350 (110–700)#		EM	Inhibitory, hippocampal and cortical	Bourne and Harris (2011) and Santuy et al. (2018)
		50 (0–200) AMPARs#	EM	Excitatory, various CNS regions	Masugi-Tokita et al. (2007), Tarusawa et al. (2009) and Fukazawa and Shigemoto (2012)
		30 (0–200) GABAARs#	Electrophysiology, EM	Inhibitory, cerebellar and hippocampal	Nusser et al. (1997, 1998)
		30 (40–500) PSD-95#	Biochemistry, TIRF microscopy	Excitatory, various brain regions	Sugiyama et al. (2005) and Sheng and Kim (2011)
		30 (40–500) Gephrin#	SMLM (decay recordings)	Inhibitory, spinal cord	Specht et al. (2013) and Patrizio et al. (2017)

*Mean values obtained in the cited studies; ^#mean (range in brackets). Values were taken directly or calculated from those reported in the cited studies.