SBF-SEM analysis of CC membrane carriers. (A) A cartoon illustrating the results presented in (B–D). The illustration includes the region from the distal inner segment to the CC in a mouse rod. Our staining/fixation protocol predominantly labels plasma membrane, intracellular membrane structures, and the extracellular matrices (ECM) in the CP, but non-membranous, cytoplasmic constituents, such as AxMT, basal body, and rootlets were not detected. (B–D) Three representative consecutive block face images collected by SFB-SEM (spanning 70 nm) revealed the vesicles located in the CC outer shaft (black arrowheads) and those in the CC inner shaft (black arrows). White arrowhead points to the vesicles at the CC outer shaft entry site. White arrows point to the vesicles towards the base of the CC as well as those aligned inside (or just beneath) the basal body lumens. Curved black arrows point to large clear vesicles. Bracket points to the predicted position of the basal body. Scale bar in nm.