Final answer:
The concentric layers of calcified material in the osteons of compact bone are called lamellae, which surround the central Haversian canal containing blood vessels, nerves, and lymphatic vessels.
Step-by-step explanation:
The concentric layers of calcified material in osteons of compact bone are called lamellae (singular = lamella). Osteons, also known as Haversian systems, are the basic structural unit of compact bone. They comprise a series of these lamellae, which are organized into rings, encircling a central (Haversian) canal. This canal houses blood vessels, nerves, and lymphatic vessels.
Osteons are cylindrical structures aligned parallel to the long axis of the bone, bolstering the bone's ability to withstand stress and prevent fracturing. Furthermore, the osteocytes, which are mature bone cells, reside in spaces called lacunae at the borders of the lamellae. They are interconnected through minuscule channels known as canaliculi, facilitating the transport of nutrients and removal of wastes.