Microtubules are intracellular structures that are shaped like long cylinders or tubes. Generally, onr will be between 20 and 25 nanometers in diameter, and can be impacted by the introduction of various medications. It is utilized by eukaryotic cells to regulate shape and control of cell movement within the organism.
In actual structure, a microtubule is composed mainly of the tubulin, a naturally manufactured protein. From an outward appearance, it will appear as a long and stiff unit that is round in construction. The walls are usually very resilient and somewhat stiff in composition. Along with playing an important role in the growth and shape of cells, the tubes also help in the process of cell division and motility.
One characteristic of the microtubule is that the actual size of the tube will fluctuate depending on the need for function. When cells are in need of additional material to aid in cell division or for motility, the microtubule will expand and begin the process of manufacturing the needed material. Once the job is complete,it will shrink somewhat in size and go into a semi dormant state, until reactivated by the cell for additional work. The tube can shrink and expand multiple times during the life of the cell, with no apparent decrease in efficiency over time.
Considered to be one of the major components of the cell cytoskeleton, the microtubule aids in just about all types of cell function. It is part of such important tasks as vesicular transport, cytokinesis, and mitosis. While much is understood about the working of the microtubule, there are still many mysteries about how the tube is activated, such as what causes it to shrink after performing a task, and what triggers it to grow again when needed by the cell.