Molecular mechanism underlying the formation of the MOs. (A) Schematic diagram showing the domains of DCX-EMAP and their molecular functions. (B) Molecular organization of the microtubule-based cytoskeleton in the outer segment. Upper inset, molecular organization of the microtubules and EDMs in the MO. Lower inset, the molecular basis of ciliary transport of DCX-EMAP. (C) The molecular mechanism underlying the functions of DCX-EMAP in the formation of the MOs. X_ex: Extracellular factor that regulates the localization of NompC.