Osteoid

Osteoid is a protein mixture which is secreted by osteoblasts. When it mineralizes, it becomes bone. Osteoid is primarily composed of Type I collagen.

When there is insufficient mineral or osteoblast dysfunction, the osteoid does not mineralize properly, and it accumulates. This process is called osteomalacia. Osteomalacia, when present in children, is defined as rickets.