Final Answer:
The centrosome contains structures called centrioles that serve as nucleation sites for the formation of microtubules.
Step-by-step explanation:
The centrosome is a cellular organelle involved in the organization of the microtubule cytoskeleton during cell division. It consists of a pair of centrioles surrounded by a protein matrix. The centrioles, cylindrical structures composed of microtubules arranged in a specific pattern, play a crucial role in nucleating the assembly of microtubules.
During cell division, the centrosome duplicates, and each pair of centrioles migrates to opposite poles of the cell. As the cell prepares for mitosis, microtubules grow outward from the centrioles, forming the mitotic spindle that helps segregate chromosomes. The centrioles act as nucleation sites for the polymerization of tubulin subunits into microtubules.