Segmentation of spherical and elliptical synaptic vesicles in rat hippocampal neurons. (A and B) 3D reconstructions showing spherical (blue) and elliptical (yellow) vesicles in excitatory (A) and inhibitory (B) synapses. (C and D) 2D slice of the tomogram shown in A. (C) The labels for elliptical vesicles were discarded but the position of these vesicles is indicated with asterisk (*). (D) In this panel, the post-thresholding label of the elliptical vesicles was retained. Scale bar, 100 nm. Tomograms are EMD-30364 and EMD-30365 (Tao et al., 2018).