Figure 4. Ultrastructural analysis of the different vesicle pools in Otof ^C2C/C2C IHC ribbon synapses.

(A) Representative transmission electron micrographs of ribbon synapses from an Otof ^C2C/+ IHC (upper panels) and an Otof ^C2C/C2C IHC (lower panels). Side views of the electron tomographic reconstruction of Otof ^C2C/+ and Otof ^C2C/C2C ribbon synapses are overlaid on the 3D tomograms. Renderings show the presynaptic plasma membrane (green) relative to the ribbon (purple), vesicles of the presumptive readily-releasable pool (RRP) in red, of the ribbon-associated pool (RAP) in blue, and of the outlying pool (OP) in orange. The ribbon was made semitransparent for visualization of its 3D shape and of the vesicles behind it. (B) Mean numbers of vesicles in the RRP, RAP, and OP of reconstructed Otof ^C2C/+ (n = 7) and Otof ^C2C/C2C (n = 10) ribbon synapses. (C) Mean vesicle densities in the RAP and OP of reconstructed Otof ^C2C/+ (n = 7) and Otof ^C2C/C2C (n = 10) ribbon synapses. (D) Mean Euclidean distance from RRP vesicle centers to the plasma membrane and from RAP vesicle centers to the ribbon in reconstructed Otof ^C2C/+ (n = 7) and Otof ^C2C/C2C (n = 10) ribbon synapses. Data information: In (B–D), data are presented as the mean ± SEM. **p<0.01, ns not significant (Student's t-test with Welch correction).

Figure 4—video 1. Example of a ribbon synapse from an Otof ^C2C/+ mouse reconstructed by electron tomography.

Download video file ^{(8.4MB, mp4)}

DOI: 10.7554/eLife.31013.009

Figure 4—video 2. Example of a ribbon synapse from an Otof ^C2C/C2C mouse reconstructed by electron tomography.

Download video file ^{(10.7MB, mp4)}

DOI: 10.7554/eLife.31013.010