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PoisedTanzanite3501

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Ahram Canadian University

Prof. Dr. Somaya Zaghloul Dr.Alshaymaa Aboulkhair

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biology anatomy cartilage medical science

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These lecture notes provide a comprehensive overview of cartilage, covering its types, structure, and functions. The document details the different types of cartilage and their characteristics, with explanations and diagrams. It also touches on the functions of cartilage in the body.

Full Transcript

CARTILAGE Prof. Dr. Somaya Zaghloul Dr.Alshaymaa Aboulkhair Introduction to Cartilage The cartilage is a Type of connective tissue. 1-The connective tissue is formed of three components (cells, fibers and ground substance). 2. The ground substance combined with the different type...

CARTILAGE Prof. Dr. Somaya Zaghloul Dr.Alshaymaa Aboulkhair Introduction to Cartilage The cartilage is a Type of connective tissue. 1-The connective tissue is formed of three components (cells, fibers and ground substance). 2. The ground substance combined with the different types of fibers forming the major component of the connective tissue, the extracellular matrix. According to the matrix we have: 1. Soft matrix in the connective tissue proper. 2. Firm matrix in cartilage. 3. Calcified matrix in bone. Cartilage Characters of cartilage: 1. Cartilage arises from (Origin) primitive UMCs. 2. It is avascular (Non-vascular) nourished by diffusion of O₂ and nutrients from the surrounding C.T. or synovial fluid in the joint cavities. 3. It has no lymph vessels or nerves. 4. It is covered by the Perichondrium except white fibro-cartilage. Types of cartilage: There are three types of cartilage based on the amount of ground substance and type of fibers embedded in it. The three types are Hyaline, Yellow Elastic and White-fibro Cartilage. 1. HAYALINE CARTILAGE It is the most common type. It appears translucent with glassy appearance (Hyalo = Glass). Sites: 1. Costal cartilages. 2. Long bones of foetal skeleton. 3. Articular cartilage. 4. Trachea and bronchi. 1. HAYALINE CARTILAGE A. Perichondrium: It is a connective tissue membrane. found on the surface of the cartilage. It is formed of two Layers: a. Outer fibrous layer:Made of collagenous fibres and fibroblasts. It is rich in blood vessels. b. Inner chondrogenic (Cellular) layer:Contains chondroblasts. Functions of perichondrium a. Nutritive function the blood vessels supply the cartilage with nutrition (by diffusion). b. Chondrogenic function (formation of new cartilage), during growth and regeneration. c. Gives attachment to muscles and tendons. B. Cartilage Cells. 1. Chondroblasts (Immature cartilage cells) Origin: UMCs. Site: At the inner chondrogenic layer of perichondrium. The light microscope (LM): Flat cells with flat pale stained nucleus and prominent nucleolus (Euchromatic nucleus). Cytoplasm is deep basophilic. It can divide. The electron microscope (EM): Features of (protein secreting cells) with abundant rER well developed Golgi apparatus and many mitochondria. Functions of chondroblasts: 1. Formation of cartilage matrix & change to Chondrocytes. 2. Appositional growth of cartilage, they can divide so their proliferation leads to (cartilage growth from outside). 2- Chondrocytes (mature cartilage cells) The superficial chondrocytes: Small, oval and arranged parallel to the surface. They are present singly in their lacunae. The deeper chondrocytes: large, rounded or triangular. They divide once or twice giving clusters of cells formed of 2 or 4 up to 8 cells in their lacunae. Such groups are called isogenous groups (Cell nests). They contain glycogen granules and lactic acid. The electron microscope (EM): Features of (protein secreting cells). Functions of chondrocytes: 1. Maintain the cartilage matrix by continuous secretion of new matrix around them. 2. Interstitial growth of cartilage (growth from inside). 3. Matrix It appears homogeneous and basophilic. Its basophilia is due to the presence of chondroitin sulphate & hyaluronic acid. The matrix contains collagen fibres type II. They do not appear because: a. They are very thin to be seen by the LM. b. They have the same refractive index of the matrix. Functions of hyaline cartilage 1. Form the skeleton of the fetus. 2. Keeps air ways open. (Trachea & Bronchi). 3. Gives smooth sliding surface to joints for easy movements of bones. (Articular surfaces). 4. Development and growth of bone 2. YELLOW ELASTIC CARTILAGE Sites: 1. Ear pinna. 2. External auditory meatus. 3. Eustachian tube. 4. Epiglottis. Structure: 1. Covered with perichondrium. 2. Similar to hyaline cartilage. 3. The matrix contains large amount of branching yellow elastic fibres. 4. Also it contains few collagen Fibers. Function: It is very flexible that recovers its shape after being reformed. 2. YELLOW ELASTIC CARTILAGE 3. WHITE FIBRO CARTILAGE Sites: 1. symphysis pubis. 2. Intervertebral discs. 3. Mandibular joint. Structure: 1. It is not covered with perichondrium. 2. Matrix is a very little amount embedded in it: a. parallel thick bundles of collagen fibers (Type I). b. Chondrocytes inside lacunae present in rows between collagen bundles. Function: 1. It can resist great pressure and stretch of joints because of its strength. 2. It attaches bone to bone with limited motility.

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