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.
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. This combination of collagen and calcium makes bone strong and flexible enough to withstand stress. Does cartilage grow back? Although articular cartilage is not capable of regrowing or healing itself, the bone tissue underneath it can. By making small cuts and abrasions to the bone underneath the area of damaged cartilage, doctors stimulate new growth.
In some cases, the damaged cartilage is cleared away completely to do this procedure. Do bones have nerves? Bones are discrete organs made up of bone tissue, plus a few other things. The main misconception about bones then, is that they are made up of dead tissue. This is not true, they have cells, nerves, blood vessels and pain receptors.
What are the classification of bones? The four principal types of bones are long, short, flat and irregular. Bones that are longer than they are wide are called long bones.
They consist of a long shaft with two bulky ends or extremities. Where is fibrocartilage located? Fibrocartilage is found in the soft tissue-to-bone attachments, pubic symphysis, the anulus fibrosus of intervertebral discs, menisci, the triangular fibrocartilage and the TMJ. 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.
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