Bone is a specialized connective tissue that is the main component of the skeleton. It has several key functions in the body; it provides support and protection, it possesses marrow cavities that provide an appropriate microenvironment for hematopoiesis, it serves as a reservoir of calcium and phosphate, and it allows for body movements. Bone is a particularly unique connective tissue because its extracellular matrix is mineralized. Mineralization of the ECM, the presence of abundant type I collagen fibers, and the organization of these components into osteons or Haversian systems impart tremendous strength and rigidity to bone.

The organization of the cells and matrix of compact bone into osteons or Haversian systems provides channels for blood vessels, ensuring that osteocytes, the principal cells of bone, can receive nutrients via canaliculi. Despite this organization, compact bone is continuously remodeled, leading to the presence of partial osteons or interstitial lamellae within compact bone.

Before we look at some slides of bone, let’s review the types of bone in this table and some bone terminology in this figure.

Compact bone.