Chondrocytes are first chondroblast cells that produce the collagen extracellular matrix ECM and then get caught in the matrix. They lie in spaces called lacunae with up to eight chondrocytes located in each. Chondrocytes rely on diffusion to obtain nutrients as, unlike bone, cartilage is avascular, meaning there are no vessels to carry blood to cartilage tissue. This lack of blood supply causes cartilage to heal very slowly compared with bone. The base substance of cartilage is chondroitin sulfate, and the microarchitecture is substantially less organized than in bone.
The cartilage fibrous sheath is called the perichondrium. The division of cells within cartilage occurs very slowly, and thus growth in cartilage is usually not based on an increase in size or mass of the cartilage itself. Articular cartilage function is dependent on the molecular composition of its ECM, which consists mainly of proteoglycans and collagens. The remodeling of cartilage is predominantly affected by changes and rearrangements of the collagen matrix, which responds to tensile and compressive forces experienced by the cartilage.
Cartilage types: Images of microscopic views of the different types of cartilage: elastic, hyaline, and fibrous. There are three major types of cartilage: hyaline cartilage, fibrocartilage, and elastic cartilage.
Hyaline cartilage is the most widespread cartilage type and, in adults, it forms the articular surfaces of long bones, the rib tips, the rings of the trachea, and parts of the skull. This type of cartilage is predominately collagen yet with few collagen fibers , and its name refers to its glassy appearance.
In the embryo, bones form first as hyaline cartilage before ossifying as development progresses. Hyaline cartilage is covered externally by a fibrous membrane, called the perichondrium, except at the articular ends of bones; it also occurs under the skin for instance, ears and nose.
Hyaline cartilage is found on many joint surfaces. It contains no nerves or blood vessels, and its structure is relatively simple. If a thin slice of cartilage is examined under the microscope, it will be found to consist of cells of a rounded or bluntly angular form, lying in groups of two or more in a granular or almost homogeneous matrix. These cells have generally straight outlines where they are in contact with each other, with the rest of their circumference rounded.
They consist of translucent protoplasm in which fine interlacing filaments and minute granules are sometimes present. Embedded in this are one or two round nuclei with the usual intranuclear network. Fibrous cartilage has lots of collagen fibers Type I and Type II , and it tends to grade into dense tendon and ligament tissue. White fibrocartilage consists of a mixture of white fibrous tissue and cartilaginous tissue in various proportions.
It owes its flexibility and toughness to the fibrous tissue, and its elasticity to the cartilaginous tissue. It is the only type of cartilage that contains type I collagen in addition to the normal type II. Fibrocartilage is found in the pubic symphysis, the annulus fibrosus of intervertebral discs, menisci, and the temporal mandibular joint. Elastic or yellow cartilage contains elastic fiber networks and collagen fibers.
The principal protein is elastin. Hyaline cartilage is springy, tough, and elastic, and is found between the ribs, around the windpipe, and between the joints articular cartilage. Cartilage damage can happen in several ways. A direct injury, such as a car accident, a fall, or a sports injury can result in cartilage damage, as can wear and tear from long periods of stress. This breakdown and loss of cartilage is known as osteoarthritis and is common in the knee. Long periods of inactivity can also increase the risk of articular cartilage damage, as joints require regular movement to stay healthy.
When the cartilage is damaged, it can result in pain, stiffness, and inflammation. There may be stiffness, swelling, loss of movements, and tenderness in the affected joint. Along with a physical examination, imaging tests such as MRI may be able to reveal the damage. An arthroscopic surgical procedure can also be used to determine the extent of the damage, as well as repair it.
Arthroscopy is a less invasive surgery performed using small incisions and a tiny camera which helps the surgeon guide the small instruments used to repair the cartilage, usually in a same-day or outpatient procedure. Non-surgical treatments for cartilage damage can include special exercises, anti-inflammatory drugs, and steroid injections. Debridement involves smoothing the damaged cartilage and removing loose edges to prevent it from rubbing, and is performed via arthroscopy.
Articular cartilage function is dependent on the molecular composition of its ECM, which consists mainly of proteoglycans and collagens. The remodeling of cartilage is predominantly affected by changes and rearrangements of the collagen matrix, which responds to tensile and compressive forces experienced by the cartilage. Cartilage types: Images of microscopic views of the different types of cartilage: elastic, hyaline, and fibrous.
There are three major types of cartilage: hyaline cartilage, fibrocartilage, and elastic cartilage. Hyaline cartilage is the most widespread cartilage type and, in adults, it forms the articular surfaces of long bones, the rib tips, the rings of the trachea, and parts of the skull. This type of cartilage is predominately collagen yet with few collagen fibers , and its name refers to its glassy appearance. In the embryo, bones form first as hyaline cartilage before ossifying as development progresses.
Hyaline cartilage is covered externally by a fibrous membrane, called the perichondrium, except at the articular ends of bones; it also occurs under the skin for instance, ears and nose. Hyaline cartilage is found on many joint surfaces. It contains no nerves or blood vessels, and its structure is relatively simple. If a thin slice of cartilage is examined under the microscope, it will be found to consist of cells of a rounded or bluntly angular form, lying in groups of two or more in a granular or almost homogeneous matrix.
These cells have generally straight outlines where they are in contact with each other, with the rest of their circumference rounded.
They consist of translucent protoplasm in which fine interlacing filaments and minute granules are sometimes present. Embedded in this are one or two round nuclei with the usual intranuclear network. Fibrous cartilage has lots of collagen fibers Type I and Type II , and it tends to grade into dense tendon and ligament tissue.
White fibrocartilage consists of a mixture of white fibrous tissue and cartilaginous tissue in various proportions. It owes its flexibility and toughness to the fibrous tissue, and its elasticity to the cartilaginous tissue. It is the only type of cartilage that contains type I collagen in addition to the normal type II.
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