Final answer:
A cellular component consisting of microtubules arranged in a hollow tube is known as a centriole, which is part of the centrosome and plays a critical role in cell division.
Step-by-step explanation:
The cellular structure composed of microtubules arranged to form a hollow tube, as revealed by the electron microscope, is a centriole. Centrioles are key components involved in the process of cell division and are part of the centrosome. Each centriole is a cylinder composed of nine sets of triplet microtubules, and these play a crucial role in organizing the microtubules that make up the mitotic spindle during mitosis. Their hollow structure, which pertains to microtubules, is important for various cell functions, from maintaining cell shape to chromosome segregation during cell division.