Figure 1.

General structure of the cilium. The structural core of the cilium consists of a microtubule-based axoneme, which protrudes from the mother centriole in the basal body. Insets depict cross-sections of the microtubule structure along the distal to proximal ciliary axis. (A) Nine single microtubules of the distal segment. (B) Nine doublet microtubules of the core axoneme. (C) The transition zone contains Y-link structures (YL, purple) that link the axoneme to the membrane as well as membrane protrusions termed the ciliary necklace (CN, pink). (D) The basal body consists of nine triplet microtubules of the mother centriole and associated transition fibers (TF, orange).