part of part of in taxon cilium ciliary transition zone 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. cellular anatomical structure Eukaryota Magnoliopsida