Editing Flagellum (section)

====Internal structure====
The core of a eukaryotic flagellum, known as the [[axoneme]] is a bundle of nine fused pairs of [[microtubule]]s known as ''doublets'' surrounding two central single microtubules (''singlets''). This [[9+2 axoneme]] is characteristic of the eukaryotic flagellum. At the base of a eukaryotic flagellum is a [[basal body]], "blepharoplast" or kinetosome, which is the [[microtubule organizing center]] for flagellar microtubules and is about 500 nanometers long. Basal bodies are structurally identical to [[centriole]]s. The flagellum is encased within the cell's [[plasma membrane]], so that the interior of the flagellum is accessible to the cell's [[cytoplasm]].

Besides the axoneme and basal body, relatively constant in morphology, other internal structures of the flagellar apparatus are the transition zone (where the axoneme and basal body meet) and the root system (microtubular or fibrilar structures that extend from the basal bodies into the cytoplasm), more variable and useful as indicators of phylogenetic relationships of eukaryotes. Other structures, more uncommon, are the paraflagellar (or paraxial, paraxonemal) rod, the R fiber, and the S fiber.<ref name = "Barsanti_2006" />{{rp|63–84}} For surface structures, see below.