Ossification
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Ossification is the term use to describe a process of bone fermentation by deposition of calcium in the fetal hyaline cartilage.
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Ossification
- 1. OSSIFICATION Prof. Redem C. Deligero, MATMRS; MSES
- 2. OSSIFICATION Ossification is the term use to describe a process of bone formation by deposition of calcium in the fetal hyaline cartilage. All bones develope from the mesenchymal tissue of the embryo
- 3. TYPES OF CALCIUM DEPOSITION A. HUMORAL FACTOR Relates in the concentration of minerals in the body fluids and the solubility of calcium salts and phosphates. B. LOCAL FACTORS No further explanation but relates on something about the determinants when and where bone minerals will be deposited.
- 4. CENTERS OF OSSIFICATION 1. PRIMARY CENTER OF OSSIFICATION Ossification starts at the central part of the cartilagenous model. Portion of bone develop from this primary center of ossification is called the diaphysis. This normally appears before birth. 2. SECONDARY CENTER OF OSSIFICATION This appears at the two ends of the long bones. Usually appear after birth. The portion of this bone developed is called epiphysis.
- 5. LAWS OF OSSIFICATION 1. Epiphysis that ossify first fuse diaphysis last. The epiphysis that ossify last fuses first except the lower end of fibula. 2. Growing end of the bone is found at the area of the epiphysis that appears first fuses last. 3. The direction of the nutrients artery is always away from teh growing end. 4. In long bones, growing ends fuse with the shaft at about 20 years.
- 6. 2 TYPES OF OSSIFICATION 1. INTRAMEMBRANOUS Bones that are develop directly from embryonic mesenchymal tissue. Usually occurs in the deep layers of the dermis E.g. Cranila Vault, Mandible, and Clavicle. 2. CARTILAGENOUS OSSIFICATION Cartilage is formed first from the mesenchymal tissue which later on ossify to form the bone.
- 7. INTRAMEMBRANOUS OSSIFICATION 1. Formation of Matrix and Organic Components. Osteoblast cluster and secrete organic matrix components including collagen fibers. Mineralization of matrix through crystallization of calcium salts. Differentiation of osteoblats into osteocytes. 2. Ossification Center Development. Bone grow outward from this center called spicules. Osteoblast formation continue from mesenchymal cells. 3. Spongy Bone Formation Subsequent remodelling around trapped blood vessels resulted to compact bone.
- 9. CARTILAGENOUS OSSIFICATION 1. Cartilage Enlargement Chondrocyte enlargement near the center of the shaft. Surrounding matrix starts to calcify. Death of chondrocytes due to nutrient deprevation. 2. Periosteum Formation Perichondrium is converted to periosteum. Perichondrium cells converted to osteoblast. Inner organic layer produces thin layer of bone arround the shaft of cartilage. 3. Spongy Bone Formation Osteoblast replaces calcified cartilagenous matrix. Increase blood supply to perichondrium. Capillaries and osteoblast invade spaces left by disintegrating chondrocytes. 4. Marrow Cavity Formation Bone is still spongy when its diameter is small. As it enlarges osteoblast forms the marrow cavity.
- 10. OSSIFICATION PLATES 1. Zone of Reserve Cartilage - Chondrocytes randomly distributed throughout the matrix and are mitotically active. 2. Zone of Proliferation - The chondrocytes rapidly proliferate that form rows of isogenous cells that are parallel to the direction of bone growth. 3. Zone of Maturation and Hypertrophy - Chondrocytes mature, hypertrophied and accumulate gylcogen in their cytoplasm. The matrix in their lacunae narrows with a corresponding growth of lacunae. 4. Zone of Calcification - Lacunae becomes confluent, hypertrophied chondrocytes die and cartilage matrix becomes calcified. 5. Zone of Ossification - Osteoprogenitor cells invade the area and differentiate into osteoblast, which elaborate matrix that becomes calcified on the surface of calcified cartilage. This is followed by resorption of the calcified cartilage/ calcified bone complex.