Centrosome, Centrioles and Microtubules (structures contained in cells)

• Microtubules are thick diameter (25 nanometers) intracellular structures which appear as straight rods when viewed under electron microscopy.
  • They are dynamic structures which can collapse and reform within seconds. Microtubules form the framework of the cell division spindles (mitotic spindle): this enables the distrubution of the chromosomes to the daughter cells. 
  • Did you know: microtubules are targets of cancer therapy, which are mitotically very active. Paclitaxel inhibits the formation of the mitotic spindle, and is used as a chemotherapeutical drug agains melanoma.
• Centrosomes act as a microtubule organizing center, controlling the turnover and distribution of microtubules. They contain structures (centrioles), which occur in pairs and position at right angles to each other. Early in cell division centrioles separate and migrate to opposite ends of the cell to organize the microtubules that make up the mitotic spindle.

Reference: The Cell: A Very Short Introduction. Allen T. Oxford University Press