Final answer:
The axoneme has a 9 + 2 microtubule array running longitudinally, important for the structure and movement of cilia and flagella, and can be observed distinctly after treatment with detergents.
Step-by-step explanation:
The axoneme contains an array of microtubules that runs longitudinally through the entire organelle. When we refer to the structure of cilia and flagella, both characterized by their 9 + 2 array of microtubules, we're discussing a ring of nine microtubule doublets that encircle two central microtubule singlets.
These structures arise from a basal body that anchors the axoneme to the cell and resembles the structure of centrioles. Each microtubule doublet in the axoneme is formed from 13 protofilaments, creating hollow tubes approximately 25 nm in diameter. These microtubules not only support the structure of the cilia and flagella but also are involved in cell movement and the arrangement of cellular components during cell division. After treatment with detergents to remove other associated proteins, the axoneme's microtubules can be individually observed in an electron microscope, showcasing their distinct 9 + 2 arrangement.