Centrioles:
they are present in animal cells, cells of microorganisms and in lower plants. they are absent higher plants and plants. they usualyy occur in pairs at right angle to each other near one pole of nucleus.
Structure:

• each centriole is made up of 9 triplets of microtubules.
• each triplet is furthur composed of 3 tubules.
• total number of tubules in a centriole is 27.
• centrioles/ microtubules are made up of tubulin proteins.

Functions:

• just before cell division, centrioles duplicate and migrate to opposite poles giving rise to spindle fibres.
• centrioles play important role in the location of furrowing during cell division.
• centrioles also give rise cilia.

Cytoskeleton:
Cytosol contains cytoskeletal fibric formed of microtubules, microfilaments and intermediate filaments. these are distributed from nucleus to plasma membrane.
there are three types fibrics found in cytoskeleton.
Microfilaments or actin filaments:

• They are 7nm thick.
• They are made up of actin, tropomyosin and troponin proteins. 
• Their function is in internal cell motion, cuclosis, cytoplasmic streaming movement, ameoboid movement.

Microtubules:

• They are 25nm thick.
• They are made up of tubulin protein.
• They function in the formation of centrioles, basal bodies, cilia, flagella and spindles.

Intermediate filaments:

• They are 8 to 10 cm thick.
• They are composed of vimentin protein.
• They function for the maintenance of cell shape.