REAGENT or RESOURCE	SOURCE	IDENTIFIER
Antibodies
Rabbit polyclonal anti-Munc13-1	Synaptic Systems	Cat# 126-103; RRID: AB_887733
Rabbit polyclonal anti-Kv3.1b	Synaptic Systems	Cat# 242 003; RRID: AB_11043175
Guinea pig polyclonal anti-Cav2.1	Synaptic Systems	Cat# 152 205; RRID: AB_2619842
Guinea pig polyclonal anti-mGluR1α	Synaptic Systems	Cat# mGluR1a-GP-Af660; RRID: AB_2571801
Rabbit polyclonal anti-Elfn1	Synaptic Systems	Cat# 448 003; RRID: AB_ 2884915
Guinea pig polyclonal anti-pan-AMPAR	Nittobo Medical	Cat# panAMPAR-GP-Af580; RRID: AB_2571610
Guinea pig polyclonal anti-GABAAR γ2	Synaptic Systems	Cat# 224 004; RRID: AB_10,594,245
Goat polyclonal anti-mGluR1a	Nittobo Medical	Cat# mGluR1a-Go-Af1220; RRID: AB_2571800
Mouse monoclonal ant-gephyrin	Synaptic Systems	Cat# 147 021; RRID: AB_2232546
Goat anti-rabbit IgG, 5nm gold	British Biocell International	Cat# EM.GAR5; RRID:AB_1769140
Goat anti-rabbit IgG, 10nm gold	British Biocell International	Cat# EM.GAR10; RRID:AB_2715527
Goat anti- guinea pig IgG, 15nm gold	British Biocell International	Cat# EM.GAG15;
Donkey anti-guinea pig IgG, 12nm gold	Jackson ImmunoResearch	Cat# 706-205-148; RRID:AB_2340465
Donkey anti-rabbit IgG, Alexa 488	Jackson ImmunoResearch	Cat# 711-545-152; RRID:AB_2313584
Goat anti-mouse IgG, Fc_Subclass 1 specific, Alexa 488	Jackson ImmunoResearch	Cat# 115-545-205; RRID:AB_2338854
Donkey anti-goat IgG, Cy3	Jackson ImmunoResearch	Cat# 705-165-147; RRID:AB_2307351
Donkey anti-guinea pig IgG, Cy3	Jackson ImmunoResearch	Cat# 706-165-148; RRID:AB_2340460
Donkey anti-guinea pig IgG, Alexa 647	Jackson ImmunoResearch	Cat# 706-605-148; RRID:AB_2340476
Donkey anti-rabbit IgG, Alexa 647	Jackson ImmunoResearch	Cat# 711-605-152; RRID:AB_2492288
Goat anti-guinea pig IgG, Abberior Star 580	Abberior	Cat# ST580-1006-500UG;
Goat anti-rabbit IgG, Abberior Star 635P	Abberior	Cat# ST635P-1002-500UG; RRID:AB_2893229
Streptavidin, Cy3 coupled	Jackson ImmunoResearch	Cat# 016-160-084; RRID:AB_2337244
Chemicals, peptides, and recombinant proteins
Ketamine	Produlab Pharma B.V.	Cat# 2302/2/07
Xylazine	Produlab Pharma B.V.	Cat# 2303/3/07
Pipolphene	EGIS Gyógyszergyár Zrt.	Cat# OGYI-T-3086/01
K-gluconate	Sigma-Aldrich	Cat# P1847
Biocytin	Sigma-Aldrich	Cat# B4261
Alexa Fluor 594	Invitrogen	Cat# A10438
Fluo5F	Invitrogen	Cat# F14221
Phorbol 12,13-di-butyrate	Tocris	Cat# 4153
Paraformaldehyde	Molar Chemicals	Cat# BC0487491
Paraformaldehyde	EMS	Cat# 19208
Uranyle Acetate	TAAB	Cat# U008
Osmium tetroxide aqeous solution	Electron Microscopy Sciences	Cat# 19190
Osmium tetroxide crystal	Electron Microscopy Sciences	Cat# 19130
Durcupane ACM Resin Single component A	Sigma-Aldrich	Cat# 44611
Durcupane ACM Resin Single component B	Sigma-Aldrich	Cat# 44612
Durcupane ACM Resin Single component C	Sigma-Aldrich	Cat# 44613
Durcupane ACM Resin Single component D	Sigma-Aldrich	Cat# 44614
Picric acid	Sigma-Aldrich	Cat# 197378
Slowfade Diamond	Invitrogen	Cat# S36967
Vectashield	Vector Laboratories	Cat# H-1000
Normal goat serum (NGS)	Vector Laboratories	Cat# S-1000
1-Hexadecene	Sigma-Aldrich	Cat# H700-9
Protein A-conjugated 10 nm gold	Cytodiagnostic	Cat# AC-10-05
Tannic acid	Sigma-Aldrich	Cat# T-0125
Gramicidin from Bacillus aneurinolyticus (Bacillus brevis)	Sigma-Aldrich	Cat# G5002
Experimental models: Organisms/strains
Mouse C57Bl6/J	Jackson	Cat# JAX:000,664; RRID:IMSR_JAX:000,664
Mouse Tg(Chrna2-Cre)OE25Gsat/Mmucd	MMRRC	RRID:MMRRC_036502-UCD
Mouse Ai9 (Gt(ROSA)26Sor_CAG/LSL_tdTomato)	Jackson	Cat# JAX:007,909; RRID:IMSR_JAX:007,909
Mouse Ai (Gt(ROSA)26Sor_CAG/LSL_tdTomato)	Jackson	Cat# JAX:007,914; RRID:IMSR_JAX:007,914
Software and algorithms
ImageJ	National Institute of Health	https://imagej.nih.gov/ij; RRID: SCR_003070
Mes v4.6	Femtonics	https://femtonics.eu/
Adobe Photoshop CS3	Adobe	https://www.adobe.com/hu/products/photoshop.html
OriginPro 2020b (Academic)	OriginLab	https://www.originlab.com/
Multiclamp (version 2.2)	Axon Instruments/Molecular Devices	https://www.moleculardevices.com/
Clampex (version 10.7)	Axon Instruments/Molecular Devices	https://www.moleculardevices.com/
Imod	Mastronade Group, University of Colorado	https://bio3d.colorado.edu/imod
SerialEM Version3.8.9	Mastronade Group, University of Colorado	https://bio3d.colorado.edu/SerialEM
MATLAB	Mathworks	N/A
GoldExt	Nusser Lab	http://www.nusserlab.hu/
Point Pattern Analysis	Rebola et al. (2019)	https://github.com/SynDiversity
Other
Vibratome VT1200S	Leica	https://www.leica-microsystems.com/
Ultramicrotome EM UCT	Leica	https://www.leica-microsystems.com/
Olympus FV3000 Confocal microscope	Olympus	https://www.olympus-lifescience.com/
Femto 2D microscope	Femtonics	https://femtonics.eu/
Mai Tai femtosecond pulsing laser	Spectra-Physics	https://www.spectra-physics.com/
Nikon Eclipse FN1 microscope	Nikon	https://www.nikon.com/
Multiclamp 700B amplifier	Axon Instruments/Molecular Devices	https://www.moleculardevices.com/
DMZ Zeits Puller	Zeitz	https://www.zeitz-puller.com/
Borosilicate glass capillary	Sutter Instruments	Cat# BF150-86-10
Jeol JEM1011 Transmission electronmicroscope	Jeol	https://www.jeol.co.jp/
Tecnai G2 Spirit BioTWIN transmission EM	Fei Europe Nanoport (Thermofisher Scientific)	https://www.fei.com/
Xarosa CMOS camera	EMSIS GmbH	https://www.emsis.eu/
Leica EM ACE900 Freeze Fracture System	Leica Microsystems	https://www.leica-microsystems.com/
Leica HPM100 High-Pressure Freezing System	Leica Microsystems	https://www.leica-microsystems.com/
Aluminum specimen carriers (type A)	Leica Microsystems	Cat# 16770141
Aluminum specimen carriers (type B)	Leica Microsystems	Cat# 16770142