PRESENCE OF MULTIPLE CENTRIOLES AND PRIMARY CILIA DURING GROWTH AND EARLY DIFFERENTIATION IN THE MYOBLAST CO25 CELL-LINE

CO25 cells, a mouse myoblast line, contain multiple centrioles and pri mary cilia. A most unusual feature has been the finding of large numbe rs of separate structures in single cells-up to a maximum of nine cent rioles, six primary cilia, and 12 of both organelles together. Aberran t multipolar spindles were occasionally seen containing variable numbe rs of centrioles. This strongly suggests that cells containing supernu merary centrioles and cilia are lost during mitosis, and that addition al centriolar structures are generated during each interphase. No chan ge in centriole or primary cilium frequency was detected after inducin g the differentiation of myoblasts into myotubes. However, a significa nt migration of these structures occurred from a perinuclear to a supr anuclear position prior to and during the phase of myoblast elongation . This shift was not maintained during cell fusion, when a net migrati on back to the periphery was observed, suggesting that it may have som e function in relation to cell elongation and the change in the patter n of microtubule distribution which occurs as part of the process. (C) 1996 Academic Press Limited.