Thick layers of dense type I and type II collagen fibers Contains the fewest chondrocytes Perichondrium Present Not present Examples Cartilaginous rings of the trachea Nasal septum Cartilaginous precursor of bone primordial bones Auricle External auditory canal Epiglottis Covers articular surfaces of synovial joints Menisci of the knee joint Intervertebral discs Pubic symphysis. References Standring S. Accessed: November 18, The role of chondronectin and cartilage proteoglycan in the attachment of chondrocytes to collagen.
Prog Clin Biol Res. David Eyre. Collagen of articular cartilage. Arthritis Res. Open in Read by QxMD. Resilience to friction Most abundant type of cartilage, but weakest. High resilience to bending Very flexible. Shock absorption Uniform distribution of force over the joint surface. Slide 71 Hyaline cartilage, Gallocyanin and Azure A stain. Again, note the perichondrium , chondrocytes in lacunae, capsule , isogenous groups , and territorial and interterritorial matrix. Supplemental Slide Developing bone.
This slide shows an example of articular cartilage , which has no perichondrium. It is a specialized type of hyaline cartilage found at the ends of articulating bones.
For example, the Van Giesen stain stains elastic fibres black. In elastic cartilage, the chondrocytes are found in a threadlike network of elastic fibres within the matrix. Elastic cartilage provides strength, and elasticity, and maintains the shape of certain structure such as the external ear. It has a perichondrium. Cartilage: The three types of cartilage There are three types of cartilage: Hyaline - most common, found in the ribs, nose, larynx, trachea. Is a precursor of bone. Elastic or yellow cartilage contains elastic fiber networks and collagen fibers.
The principal protein is elastin. Elastic cartilage is histologically similar to hyaline cartilage but contains many yellow elastic fibers lying in a solid matrix.
These fibers form bundles that appear dark under a microscope. They give elastic cartilage great flexibility so it can withstand repeated bending. Chondrocytes lie between the fibers.
Elastic cartilage is found in the epiglottis part of the larynx and the pinnae the external ear flaps of many mammals, including humans. Chondrification also known as chondrogenesis is the process by which cartilage is formed from condensed mesenchyme tissue. A chondrocyte: A chondrocyte, stained for calcium, showing its nucleus N and mitochondria M. Mesenchyme tissue differentiates into chondroblasts and begins secreting the molecules that form the extracellular matrix ECM.
Mesenchymal stem cells MSCs are undifferentiated, meaning they can give rise to different cell types. Under the appropriate conditions and at sites of cartilage formation, they are referred to as chondrogenic cells.
During cartilage formation, undifferentiated MSCs are highly proliferative and form dense aggregates of chondrogenic cells at the center of chondrification. These condrogenic cells then differentiate to chondroblasts, which will then synthesize the cartilage ECM. Cartilage: Hyaline cartilage showing chondrocytes and organelles, lacunae and matrix.
The extracellular matrix consists of ground substance proteoglycans and glycosaminoglycans and associated fibers, such as collagen.
The chondroblasts then trap themselves in lacunae, small spaces that are no longer in contact with the newly created matrix and contain extracellular fluid. The chondroblast is now a chondrocyte, which is usually inactive but can still secrete and degrade the matrix depending on the conditions. The majority of body cartilage is synthesized from chondroblasts that are largely inactive at later developmental stages compared to earlier years pre-pubescence. The division of cells within cartilage occurs very slowly.
Therefore, growth in cartilage is usually not based on an increase in size or mass of the cartilage itself.
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