part of ends during starts during death cell part centriole A cellular organelle, found close to the nucleus in many cells, consisting of a small cylinder with microtubular walls, 300-500 nm long and 150-250 nm in diameter. It contains nine short, parallel, peripheral microtubular fibrils, each fibril consisting of one complete microtubule fused to two incomplete microtubules. Cells usually have two centrioles, lying at right angles to each other. At division, each pair of centrioles generates another pair and the twin pairs form the pole of the mitotic spindle. XAO:0005011 eriksegerdell xenopus_anatomy 2015-05-14T17:51:38Z GO:0005814 centrosome NF stage 1