The area immediately adjacent to the cell is called the capsule and stains intensely because of the rich glycosaminoglycan content. Clusters of cells arising from mitosis are called isogenous groups. Hyaline cartilage is easily distinguished from elastic and fibrocartilage because of the homogeneous no fibers are visible extracellular matrix ECM. The darker staining matrix immediately surrounding the capsule is called territorial matrix , while the matrix that occupies the majority of space between chondrocytes is interterritorial matrix.
Slide 71 Hyaline cartilage, Gallocyanin and Azure A stain. Identify the chondrocytes in lacunae , and thick bundles of collagen fibres. This is the strongest kind of cartilage, because it has alternating layers of hyaline cartilage matrix and thick layers of dense collagen fibres oriented in the direction of functional stresses.
This type of cartilage does not have a perichondrium as it is usually a transitional layer between hyaline cartilage and tendon or ligament. The picture above is a section of elastic cartilage, stained so that you can see the elastic fibres.
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. The Van Geison stain uses picric acid and acid fuchsin and stains collagen red. The cartilage is viewed as a red zone lying below the epithelium. The staining is lighter where it becomes closer to the lacunae indicating the territorial matrix.
The territorial matrix is dark, and the interterritorial matrix is a lot lighter in color. These chondrocytes are derived from the same progenitor and are therefore an isogenous group.
The perichondrium surrounds the cartilage except in the articular cartilage. There are 3 different cartilage types found in the body. Hyaline cartilage is the most common but also the weakest type of cartilage. The other two types of cartilage are fibrocartilage and elastic cartilage.
How is hyaline cartilage different from elastic cartilage or fibrocartilage? See below to see descriptions of each cartilage type. The visual differences between the types of cartilage can be seen in Figure 1.
Let us look at Hyaline cartilage vs elastic cartilage. Elastic cartilage or yellow fibrocartilage provides strength and elasticity to certain parts of the body. Where is elastic cartilage found? Elastic cartilage functions to give support with additional elasticity.
It contains a dense network of elastin fibers. It does not protect from mechanical stress or compression. More details such as elastic cartilage locations and appearance are highlighted in table 1 below. Fibrocartilage connective tissue is a dense flexible and supporting cartilage made up of fibrous tissue. Where is fibrocartilage found?
Fibrocartilage locations include the intervertebral discs of the spine , in the jaw , and the knee and wrist. This fibrocartilage tissue contains large bundles of type I collagen. It is the strongest type of cartilage. Fibrocartilage functions to give support against weight-bearing and pressure forces.
Fibrocartilage vs hyaline cartilage, as well as the locations in the body where fibrocartilage is located, is described in table 1 below. So, what is the function of hyaline cartilage?
Hyaline cartilage contains relatively few fibers and provides a smooth surface for movement as well as a cushion that absorbs shock where the bones meet. In articular cartilage, the primary function is to provide a smooth surface that can withstand friction and pressure from weight-bearing functions.
In the trachea, it provides support for the softer tissues and allows them to maintain an open position. The most important role of hyaline cartilage is to provide mechanical support for the respiratory system, developing bones and articular surfaces. As we age, problems with the quality of our hyaline cartilage can arise. With increased age, the number of chondrocytes in the superficial layer of articular cartilage drops whereas the number of chondrocytes in the deeper layers increases.
Also, with an increase in age is a decrease in proteoglycans in the extracellular matrix. There is also an increase in keratin sulfate and a decrease in chondroitin sulfate. The volume of hyaluronic acid also increases. Hyaline cartilage is susceptible to wear and tear due to its role as a shock absorber and heavy use in daily activities.
All these factors can lead to hyaline cartilage becoming more susceptible to damage and disease than the other types of cartilage. Cartilage tissues are likely to be slow in healing following an injury because there is a lack of blood supply to the chondrocytes. This means that the matrix is slow to form. Also, chondrocytes are stuck in lacunae and cannot migrate to an area of damaged tissue. Damaged tissue becomes scar tissue. In the extracellular matrix, chondroitin sulfate plays an important part as it is an anti-inflammatory mediator and reduces pain.
Some studies suggest its presence helps slow the break-down of cartilage and thereby prevents conditions such as osteoarthritis. Osteoarthritis occurs when the cartilage wears away, allowing the bones to rub against each other causing subchondral bone bone just below the cartilage sclerosis hardening , and inflammation of the synovial membrane leading to pain. Animals in the class Chondrichthyes have a skeleton composed completely of cartilage.
Sharks and rays are good examples of this. Cartilage is less dense than bone, yet still provides strength and therefore allows these animals to move quickly through the water without exerting too much effort. Cartilage is also found in invertebrates , such as horseshoe crabs , snails , and cephalopods predatory mollusks e. The branchial cartilage in the arthropod Atlantic horseshoe crab Limulus polyphemus , is rich in vacuolated chondrocytes that differs from any other arthropod.
Endosternite cartilage is another type found in this species. 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. Elastic cartilage is histologically similar to hyaline cartilage but contains many yellow elastic fibers lying in a solid matrix.
0コメント