The microtubular cytoskeleton in the cortical ciliature of the Oxytricha platystoma was visualized by direct fluorescent labeling of FLUTAX and laser scanning confocal microscopy.The distribution pattern of base-associated microtubules was found to be in accordance with that of adoral zone membranelles (AZM), dulating membranes (UM), frontal-ventral-transverse cirri (FVTC), and left-right marginal cirri (L-RMC).The microtubular cytoskeleton of the AZM comprised of membranelle brackets and its connected microtubules as well as the base-associated microtubules.The base-associated microtubules of the UM contained well-developed microtubule cytoskeletal net.The confluence of AZM and UM contained the oral-end bracket and postoral microtubules.The base-associated microtubules of the FVTC, L-and RMC contained anterior longitudinal microtubules (ALM), posterior longitudinal microtubules (PLM) and transverse microtubules (TM) or radiate microtubules (RM).The results show that cortical ciliature base microtubules of O.platystoma have their species specificity, such as, UM of the O.platystoma form well-developed microtubule net at the base of the special long cilia series.The structure of such large AZM, UM and the base-associated microtubule skeleton have not been reported in ciliates.In addition, the oral-end bracket and postoral microtubules may be prevalent in hyportrichia ciliate base of adoral ciliature microtubules.