Cartilage Tissue PDF

CARTILAGE TISSUE Lecturer Nilsu TALAŞ  2 1 3  Connective Tissue Epithelial Tissue Cartilage Tissue  General Properties of Cartilage Tissue  Cartilage; It is a form of connective tissue consisting of chondroblasts, chond...

CARTILAGE TISSUE Lecturer Nilsu TALAŞ  2 1 3  Connective Tissue Epithelial Tissue Cartilage Tissue  General Properties of Cartilage Tissue  Cartilage; It is a form of connective tissue consisting of chondroblasts, chondrocytes and abundant extracellular matrix.  More than 95% of cartilage volume consists of extracellular matrix.  It is an avascular tissue.  It does not contain lymph vessels and nerves. There is no vascular network in cartilage. The structure of the extracellular matrix should provide a suitable environment for the diffusion of nutrients. In the matrix, the proportion of GAGs is higher than type II collagen. It allows the diffusion of substances between chondrocytes and thus ensures continuity of tissue vitality.  Types of Cartilage HYALINE ELASTIC FIBROUS CARTILAGE CARTILAGE CARTILAGE  Types of Cartilage Hyaline Cartilage Elastic Cartilage Fibrous Cartilage Type II collagen Type II collagen Type II collagen GAG GAG GAG Proteoglycan Proteoglycan Proteoglycan Glycoprotein Glycoprotein Glycoprotein ELASTIC FIBER TYPE I COLLAGEN  Hyaline Cartilage It is the most common Surfaces of joints type of cartilage in the organism. It is surrounded by perichondrium. Nose, Larynx (Except articular cartilage) Hiyalin Cartilage It forms the skeleton in Trachea the embryonic and early Wall of bronchi fetal periods. It is the active area that ensures bone Ventral ends of ribs formation and development in the epiphyseal plates after birth until Epiphyseal plate puberty. It can be calcified Structure of Hyaline Cartilage Cells % 3-5 Chondrocytes Glycoproteins % 5 Proteoglycans (aggrecan) %9 %5 %15 %80 Collagen %15 III, VI, X, XII, XIV IX,XI II Intercellular water %60-80  Perichondrium It is a dense connective tissue that surrounds the cartilage externally, consisting of elastic, collagen fibers (Type I) and fibroblast-like cells. It is defined as the sheath of cartilage. It consists of two layers:  Outer fibrous layer: Fibroblast, collagen fibers It is rich in blood vessels.  Inner chondrogenic layer: Contains chondroblasts. Cells of Cartilage Tissue Chondroblast (Immature) Intercellular substance production Presence in the perichondrium Dividing by mitosis to form chondrocytes Lots of rER Basophil staining Dense Golgi complex Lipid droplets, glycogen Chondrocyte (Mature) Large, oval shaped Embedded in lacunae (space) Coming together to form an isogenous group Less secretion Isogenous grups Chondroblast mitosischondrocyte groups = Isogenous group  Chondrocytes Chondrocyte cells located within lacunae During histological techniques, chondrocytes shrink by losing water, lipid and glycogen content. A space is observed between the lacuna and the wall of cell. Your Text Here Your Text Here Your Text Here Chondrocytes Chondrocytes (Live view) (Microscopic view)  Matrix of Hyaline Cartilage Proteoglycans Glycosaminoglycans Aggrecan Hyaluronan Decorin Chondroitin sulfate Keratan sulfate Glycoproteins Collagen Tenascin Fibronectin 2, 6, 9, 10, 11 Anchorin CII Chondrocyte Cartilage-specific collagen molecules Fibrous Intercellular Matrix of Cartilage Tissue Cartilage Specific Collagen Types ıı vı ıx x xı Main collagen It binds to Ensuring the Enabling Adjusting type integrin interaction collagen the size of Protecting and receptors on of collagen fibers to form collagen supporting the cell fibers with a three- fibrils cartilage surface and GAGs dimensional Create physical anchors network properties chondrocytes to the matrix. Amorphous Intercellular Matrix of Cartilage Tissue (Ground Substance) Amorphous Intercellular Substance of Cartilage Glycosaminoglycans Proteoglycans Glycoproteins Hyaluronic acid Aggrecan Anchorin CII Chondroitin sulfate Tenascin Keratan sulfate Fibronectin  Since the proteoglycans of hyaline cartilage contain sulfate groups, the intercellular substance is stained with basic dyes and hematoxylin.  However, the matrix is not stained homogeneously.  Therefore, three different regions were defined according to the staining characteristics of the matrix. glycogen lipid rER isogenous Capsular group matrix Type VI collagen network Territorial Interterritorial matrix matrix Capsular-Territorial-Interterritorial Matrix Capsular Matrix (Pericellular Matrix) It is a darkly colored ring-shaped area immediately around the chondrocytes. It contains highest amount of sulfated proteoglycans and glycoproteins. It includes type VI, IX collagen Territorial Matrix It is the area that surrounds isogenous groups outside the capsular matrix. It contains less sulfated proteoglycans than the capsular matrix. It is stained as basophilic. It containds Type II, XI collagen. Interterritorial Matrix These are the regions between cell groups and the territorial matrix. Collagen fibers are more abundant and the area is less basophilic (sometimes acidophilic) stained. Territorial-Interterritorial Matrix Territorial matrix surrounds cell groups Hyaline Cartilage Trachea Hyaline cartilage and surrounding structures Hyaline Cartilage Cells and matrix of mature hyaline cartilage Hyaline Cartilage  Elastic Cartilage In addition to components of hyaline cartilage matrix, it contains ELASTIC FIBER External ear It is surrounded by perichondrium. External ear Elastic channel It is flexible and Cartilage can be bent. Epiglottis They do not undergo Larynx calcification. Elastic Cartilage Elastic cartilage in the epiglottis  Elastic cartilage, in addition to containing the normal components of the hyaline cartilage matrix, contains densely branching elastic fibers. These elastic fibers and lamellae are distinguished by resorcin fuchsin and orcein. Elastin Stain Hematoxylin and orcein Weigert resorcin and van Gieson http://faculty.une.edu/  Fibrous Cartilage It is the combination of hyaline cartilage and dense intervertebral connective tissue. disc Chondrocytes form Sternoclavicular and a cell line. temporomandibular joints Isogenous groups Fibrous Cartilage are very rare. Sympisis pubis Fibroblasts are found among chondrocyte Meniscus groups They undergo calcification during bone repair. Fibrous Cartilage intervertebral disc The tissue has a fibrous appearance and the nuclei of fibroblasts appear small, elongated or spindle-shaped. As is characteristic of dense connective tissue, a small number of fibroblasts are present. Chondrocytes are more numerous and show close groupings that is isogenous groups. Fibrous Cartilage intervertebral disc Chondrocytes are located within lacunae and their cytoplasm is darkly stained. The surrounding cartilage matrix material is sparse and mixed with dense connective tissue.  Fibrous Cartilage The majority of its volume Intervertebral consists of collagen fibers. disc Amorphous intercellular Sternoclavicular and substance amount less, poor in temporomandibular cells joints Fibrous Cartilage Contains Type I and II collagen Sympisis pubis Instead of aggrecan, there is versican produced by fibroblasts. Meniscus THERE IS NO PERICHONDRIUM AROUND FIBROUS CARTILAGE! Fibrous Cartilage Intervertebral disc  Fibroblasts-chondrocytes Chondroblast-chondrocytes Chondroblast-chondrocytes Hyaline Fibrous Elastic  Chondrogenesis Chondrogenesis, the process of cartilage development, begins with the aggregation of chondroprogenitor mesenchymal cells to form a round, closely packed mass of cells. Most cartilage originates from mesenchyme during chondrogenesis. Most of the cartilage in the head arises from aggregates of ectomesenchyme derived from neural crest cells. The area of hyaline cartilage formation is initially recognized by a collection of mesenchymal or ectomesenchymal cells known as a chondrogenic nodule. Expression of the transcription factor SOX-9 triggers the differentiation of these cells into chondroblasts. Chondroblasts synthesize cartilage matrix and turn into chondrocytes when completely surrounded by matrix material.  Growth of Cartilage Tissue Cartilage has two types of growth abilities: appositional and interstitial. 1. Appositional Growth: New cartilage formation occurs on the surface of existing cartilage (inc. diameter) 2. Interstitial Growth: New cartilage formation occurs inside the existing cartilage mass (inc. length)  Growth of Cartilage Tissue Interstistial Growth Appositional Growth  Newly produced cartilage cells are  New cartilage cells are formed derived from the inner part of the by the division of chondrocytes in perichondrium. the lacunae.  The cells resemble fibroblasts and produce  Initially, sister chondrocytes are type I collagen. in the same lacunae.  Cells enter the process of differentiation.  When the new matrix is secreted, each cell moves into its own  When cartilage growth begins, the lacunae. cytoplasmic extensions disappear, the nucleus becomes round, and the amount  Cells are separated from each of cytoplasm increases and the cells other by the continuous differentiate into chondroblasts. secretion of the matrix.  Chondroblasts produce cartilage matrix, including the secretion of type II collagen, and differentiate into chondrocytes.  Repair of Cartilage Cartilage can tolerate quite intense and repetitive stress. But when cartilage is damaged, it does not show a dramatic ability to heal from even the smallest injuries. This lack of response to injury is due to the avascularity of cartilage, the immobility of chondrocytes, and the limited ability of mature chondrocytes to proliferate. However, if the damage occurs in the perichondrium, some repair may occur. Repair in these injuries results from the activity of pluripotential progenitor cells located in the perichondrium. Avascularity Limited proliferation of chondrocytes Limited repair capacity Immobility of chondrocytes  Calcification of Hyaline Cartilage Calcification; is a process in which calcium phosphate crystals become embedded in the cartilage matrix. Hyaline cartilage tends to calcify.  Hyaline cartilage calcifies and is replaced by bone when calcium phosphate crystals are added to the cartilage matrix.  Hyaline cartilage shows calcification in 3 situations: I. In growing and adult bones, the portion of articular cartilage in contact with bone tissue becomes calcified. II. Calcification always occurs in the cartilage that is about to be replaced by bone during the growth period (endochondral ossification). III. Hyaline cartilage in the adult becomes calcified over time during the aging process.