Lamellar bone

Lamellar bone is a type of bone that is characterized by its parallel layers of collagen fibers. It is one of the two types of bone tissue found in the human body, the other being woven bone. Lamellar bone is stronger and slower to form than woven bone. It is found in the mature skeleton and makes up the bulk of adult bone mass.

Structure

Lamellar bone is composed of small, concentric layers, or lamellae, of collagen and minerals. Each lamella is approximately 3-7 micrometers thick and is oriented parallel to the surface of the bone. The collagen fibers within each lamella are also parallel to each other, but are oriented at an angle to the fibers in adjacent lamellae. This cross-ply arrangement provides strength and resilience to the bone.

Formation

The formation of lamellar bone, known as ossification, occurs in two stages. First, a temporary bone matrix of woven bone is formed. This matrix is then replaced by lamellar bone through a process called remodeling. Remodeling involves the coordinated activity of osteoblasts, which form new bone, and osteoclasts, which resorb old bone. This process can take several months to years to complete.

Function

Lamellar bone serves several important functions in the body. It provides structural support and protection for the internal organs. It also serves as a reservoir for important minerals, such as calcium and phosphorus, which can be released into the bloodstream as needed. In addition, lamellar bone plays a role in the production of blood cells, as it contains the bone marrow where these cells are produced.

Clinical significance

Abnormalities in the structure or formation of lamellar bone can lead to various bone diseases. For example, osteoporosis is characterized by a decrease in bone mass and density, which can result in fragile bones that are prone to fracture. Other conditions, such as Paget's disease of bone, involve abnormal bone remodeling, leading to enlarged and misshapen bones.