SBF-SEM analysis of CC membrane carriers near CC entry sites. Four representative consecutive block face images collected by SFB-SEM (spanning 70 nm). Black arrows point to membrane vesicles in or at the entry site of CC outer shaft. Black curved arrows point to large clear vesicles. Black arrowheads point to strings of vesicles inside the CC outer shaft. White arrows point to small vesicles closely associated with or at the vicinity of inner segment tubular network (TN). White arrowhead points to a vesicle cluster inside the basal body. Curved black arrows mark the large clear vesicles present in the basal body lumen (second panel) and distal inner segment (fourth panel). The predicted position of the basal body is labeled by a bracket. Scale bar in nm.