Physical structure of centriole
Centrioles are cylindrical and small organelles. It looks like a cylindrical barrel with two openings. It is 0.3-0.5 µm in length and about 0.15-0.25 µm in diameter. Each centriole consists of three main parts. These are-
1. Cylinder wall: At the center of the centriole there is a structure like a bullock cart wheel. It is called cart wheel model. The center of the cart wheel model is called the hub. The central rod is surrounded by walls or cylinder walls. Its wall is made up of 9 bundles or microtubules. Surrounding the centriole are 9 pericentriolar satellites above and below the microtubule.
2. Triplets: The centriole consists of 9 clusters of triplet molecules or triplets surrounding a cavity. Each tertiary microtubule has three equidistant subtubules. That is, each centriole (3×9) has 27 subtubules. Microtubules are attached to a central axis like the spokes of a wheel. Scientist Threadgold (1968) identified three subducts internally as A, B and C. The diameter of each subchannel is 250Å.
3. Linker: Linker is a type of protein fiber. The dense protein fibers that connect the tertiary tubules are called linkers. Channel A is connected to channel B and channel B is connected to channel C by connectors.
Centrioles are arranged in pairs. Each pair of centrioles is called diplosomes. The dark fluid surrounding the centriole is called the centrosphere.
Chemical structure of centriole
The main chemical component of centriole is protein. Also contains lipids and ATP.