TY - JOUR T1 - Study of the Size and Shape of Synapses in the Juvenile Rat Somatosensory Cortex with 3D Electron Microscopy JF - eneuro JO - eNeuro DO - 10.1523/ENEURO.0377-17.2017 VL - 5 IS - 1 SP - ENEURO.0377-17.2017 AU - Andrea Santuy AU - José-Rodrigo Rodríguez AU - Javier DeFelipe AU - Angel Merchán-Pérez Y1 - 2018/01/01 UR - http://www.eneuro.org/content/5/1/ENEURO.0377-17.2017.abstract N2 - Changes in the size of the synaptic junction are thought to have significant functional consequences. We used focused ion beam milling and scanning electron microscopy (FIB/SEM) to obtain stacks of serial sections from the six layers of the rat somatosensory cortex. We have segmented in 3D a large number of synapses (n = 6891) to analyze the size and shape of excitatory (asymmetric) and inhibitory (symmetric) synapses, using dedicated software. This study provided three main findings. Firstly, the mean synaptic sizes were smaller for asymmetric than for symmetric synapses in all cortical layers. In all cases, synaptic junction sizes followed a log-normal distribution. Secondly, most cortical synapses had disc-shaped postsynaptic densities (PSDs; 93%). A few were perforated (4.5%), while a smaller proportion (2.5%) showed a tortuous horseshoe-shaped perimeter. Thirdly, the curvature was larger for symmetric than for asymmetric synapses in all layers. However, there was no correlation between synaptic area and curvature. ER -