Interstitial and appositional growth

When babies are born, they have about 300 bones in their body. Their bones are made of soft and flexible cartilage. Like the tip of the nose or top of the ear. By the time they become adults, there will be about 206 bones in the adult body. What happens is that, the small bones that we are born with come together over time to form larger and longer bones. The epiphyseal plate deplete and marrow cavities unite into one cavity. As we grow, the cartilage in our bodies grow and over time it gets replaced with bones. This replacement happens with calcium. The process is called ossification. This is when layers of salt accumulate on the cartilage cells. Cartilage cells die leaving space for blood vessels to grow. Blood vessels bring Osteoblasts cells which help collect more calcium and produce collagen fibers. The Osteoblast become osteocytes and reabsorb bone matrix and some deposit it. They contribute by maintaining homeostasis of bone density and blood concentration. Ossification usually end by mid-twenties and our bones become capable of healing on there own. Growth of our bones is what increases our height. Bones elongation is because of cartilage growth. Growth of the cartilage from within is Interstitial growth. It is a form of dwarfism which is because of failure of cartilage growth in long bones. Bones grow in diameter and thickness as well. This process is called Appositional gowth which is with new tissue at the surface. Cartilage can enlarge by both Interstitial or Appositional growth. Osteoblast in the inner layer of periosteum deposit osteoid tissue on the bone surface, calcify it, and become trapped in it as osteocytes.As bones increase in diameter, its marrow cavity also becomes wide. This happens by osteoclast of the endosteum dissolving tissue on the inner bone surface.