Distribution of microtubules during centriole separation in rat kangaroo (Potorous) cells.

The distribution of microtubule profiles during separation of the centriole duplexes in prophase of rat kangaroo cells (PTK2W) has been investigated by serial section reconstructions. Separation begins with a reduction of the interphase microtubular network which radiates from the region of the duplex to all parts of the cell. As duplexes separate, microtubular elements appear between the duplexes. However, most microtubular elements extend oblique to the axis of separation rather than aligned along the axis of separation. Few microtubules are seen extending directly between duplexes. Longer profiles are seen as separation continues. Prior to the completion of separation, microtubules coalesce to form a discrete band often juxtaposed on the nuclear membrane. Subsequently, the duplexes reach their final position and nuclear envelope dissolution is initiated.