A plan for--or a summary of--a writing project or speech. An outline is usually in the form of a list divided into headings and subheadings that distinguish main points from supporting points. Most word processors contain an outlining feature that allows writers to format outlines automatically.
Osteoblasts are bone-forming cells that descend from osteoprogenitor cells. They form a protein mixture known as osteoid, which mineralizes to become bone. Osteoid is primarily composed of Type I collagen.Osteoblasts also manufacture hormones, such as prostaglandins, to act on the bone itself.steocytes: Osteocytes are mature bone cells that originate from osteoblasts, which have migrated into and become trapped and surrounded by bone matrix, produced by themselves. The spaces they occupy are known as lacunae.
Mature bone contains some osteoblasts, which build new bone, and cells called osteoclasts, which break down bone minerals. These cells enable the repair of broken or damaged bones and keep bone from becoming brittle and weak. Joints are classified into three types: Immovable, or fixed, joints allow no movement.