Distribution of fully fused vesicles or omega figures.

<p>Panel A shows a plane from the reconstruction of a ribbon synapse from a mouse dark-adapted for 15 minutes. The omega figures are located at the base of the ribbon and along the slope of the synaptic ridge, as well at ribbon-free sites. HC and BP indicate horizontal endings and bipolar cell dendrites, respectively. Panels B–D show the localization of omega figures (white dots) at ribbon-associated (panel B) and ribbon-free regions of the rod spherule (panels C–D). Bar: 60 nm.