Bone Development and Growth

August 17, 2012 | By | Reply More

Bone Development and Growth

There are two types of bone based on the way the bones form

1.  INTRAMEMBRANOUS BONES: broad, flat bones of the skull.  These bones form from membrane-like sheets of connective tissue

2.  ENCHONDRAL BONES : all other bones.

  •  Bones first form as hyaline cartilage.  The cartilage then gradually changes into bone tissue – a process called OSSIFICATION, which begins near the middle of the diaphysis in an area called the PRIMARY OSSIFICATION CENTER.  Later the bone begins to ossify in the epiphysis – these areas are called the SECONDARY OSSIFICATION CENTERS.
  • As long as growth is occurring, a “band” of cartilage (called an epiphyseal disk, growth plate) remains between the diaphysis and the epiphysis.
  •  Bones increase in length as these cartilage cells continue to reproduce and ossify
  • Cartilage cells form cells called OSTEOBLASTS.  These cells produce bone matrix and once the cell is enclosed in bone matrix it is considered to be a mature bone cell and called an OSTEOCYTE
  • Growth in thickness of bone occurs as osteoblasts from beneath the periosteum produce bone matrix and built compact bone just underneath the periosteum
  • Bone tissue is constantly being replaced as special cells called OSTEOCLASTS dissolve bone tissue from within the medullary cavity – a process called RESORPTION.  At the same time new bone tissue is being added to the outside of the bone.

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Category: Anatomy, Medical

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