part of part of in taxon cilium ciliary transition zone 2011-05-25T03:09:58Z Depending on the species, this region may have a distinct geometrically shaped electron-dense structure within the axonemal lumen visible in electron microscopy images; most animals don't display this inner structure. The axoneme extends through the ciliary transition zone, but only consists of the outer doublets. The central pair, axonemal spokes, and dynein complexes are not found in this part of the ciliary shaft. Note that the connecting cilium of the photoreceptor cells is thought to be equivalent to the transition zone. connecting cilium cilium transition zone A region of the cilium between the basal body and proximal segment that is characterized by Y-shaped assemblages that connect axonemal microtubules to the ciliary membrane. The ciliary transition zone appears to function as a gate that controls ciliary membrane composition and separates the cytosol from the ciliary plasm. cilial transition zone GO:0035869 bf cellular anatomical entity cellular anatomical structure Eukaryota