The structural units of a bone are made of_____
Haversian System
The structural units of a bone are made of Haversian systems which are also known as osteon. These include the Haversian canals, circular lamellae, lacunae (the cavities in the bone) that are filled with bone cells called Osteocytes.
Bidder's canal is present inside kidney of frog. Volkmann's canals are any of the small channels in the bone that transmit blood vessels from the periosteum into the bone and that communicate with the Haversian canals. The eustachian tube is a canal that connects the middle ear to the nasopharynx, which consists of the upper throat and the back of the nasal cavity.