Contents
What is replaced by bone matrix?
During the third phase of endochondral ossification, the chondrocytes proliferate rapidly to form the model for the bone. As they divide, the chondrocytes secrete a cartilage-specific extracellular matrix. Eventually, all the cartilage is replaced by bone.
How is the bone matrix formed?
The extracellular matrix of bone is laid down by osteoblasts, which secrete both collagen and ground substance. These synthesise collagen within the cell and then secrete collagen fibrils. The collagen fibers rapidly polymerise to form collagen strands.
What are the 3 stages of bone development?
The process of bone formation is called osteogenesis or ossification. After progenitor cells form osteoblastic lines, they proceed with three stages of development of cell differentiation, called proliferation, maturation of matrix, and mineralization.
What are the 5 steps of bone growth?
30.2A: Stages of Bone Development
- EXAMPLES.
- Initial Bone Formation.
- Intramembranous Ossification.
- Endochondral Ossification.
- Remodeling.
At what age are all bones normally ossified?
Ossification
| Time period | Bones affected |
|---|---|
| 18 to 23 years | Bone of the lower limbs and os coxae become completely ossified |
| 23 to 26 years | Bone of the sternum, clavicles, and vertebrae become completely ossified |
| By 25 years | Nearly all bones are completely ossified |
Is matrix of bone pliable?
Bone is hard as its matrix has an inflexible material, the ossein. Matrix of the bone also contains calcium and magnesium salts which also add in building rigidity of the tissue. Cartilage is soft and pliable as its matrix has a flexible material, the chondrin.
Which bones ossify first?
Ossification (or osteogenesis) in bone remodeling is the process of laying down new bone material by cells named osteoblasts. It is synonymous with bone tissue formation….Ossification.
| Time period | Bones affected |
|---|---|
| 23 to 26 years | Bone of the sternum, clavicles, and vertebrae become completely ossified |
What age does bone growth stop?
Through the growing years, a layer of cartilage (the growth plate) separates each epiphyses from the bone shaft. Between 17 and 25 years, normal growth stops. The development and union of separate bone parts is complete.
How are osteocytes connected to the bone matrix?
Like osteoblasts, osteocytes lack mitotic activity. They can communicate with each other and receive nutrients via long cytoplasmic processes that extend through canaliculi (singular = canaliculus), channels within the bone matrix. Osteocytes are connected to one another within the canaliculi via gap junctions.
How is cartilage converted into bone in the developing skeleton?
Endochondral ossification: how cartilage is converted into bone in the developing skeleton. Endochondral ossification is the process by which the embryonic cartilaginous model of most bones contributes to longitudinal growth and is gradually replaced by bone.
What makes up the microscopic unit of compact bone?
Each group of concentric circles (each “tree”) makes up the microscopic structural unit of compact bone called an osteon (this is also called a Haversian system). Each ring of the osteon is made of collagen and calcified matrix and is called a lamella (plural = lamellae).
How is bone tissue different from other tissues?
Bone tissue (osseous tissue) differs greatly from other tissues in the body. Bone is hard and many of its functions depend on that characteristic hardness. Later discussions in this chapter will show that bone is also dynamic in that its shape adjusts to accommodate stresses.