Unit 8: Cartilage PDF

 ON 8 LESS CARTILAGE  SSON8 LE CARTILAGE Concept and generalities. Histogenesis of cartilage. Cells and matrix of cartilaginous tissue. Types: Hyaline cartilage, elastic cartilage, fibrocartilage.  CARTILAGE Specialized form of connective tissue Chondrocytes (lacunae)...

 ON 8 LESS CARTILAGE  SSON8 LE CARTILAGE Concept and generalities. Histogenesis of cartilage. Cells and matrix of cartilaginous tissue. Types: Hyaline cartilage, elastic cartilage, fibrocartilage.  CARTILAGE Specialized form of connective tissue Chondrocytes (lacunae) + extracellular matrix AVASCULAR, no nerves, no lymphatic vessels Extracellular matrix: proteoglycans collagen fibers glycosaminoglycans elastic fibers Flexibility and resistance shock absorber Smooth surface friction-free movements of the joints  TYPE OF CARTILAGES According to the type of fibers : HYALINE CARTILAGE FIBROCARTILAGE ELASTIC CARTILAGE  TYPE OF CARTILAGES According to the type of fibers : HYALINE CARTILAGE The most abundant. Type II collagen ELASTIC CARTILAGE Type II collagen Abundant elastic fibers FIBROCARTILAGE Type I collagen  TYPE OF CARTILAGES According to the type of fibers : HYALINE CARTILAGE The most abundant. Type II collagen ELASTIC CARTILAGE Type II collagen Abundant elastic fibers FIBROCARTILAGE Type I collagen  TYPE OF CARTILAGES According to the type of fibers : HYALINE CARTILAGE The most abundant. Type II collagen ELASTIC CARTILAGE Type II collagen Abundant elastic fibers FIBROCARTILAGE Type I collagen  HYALINE CARTILAGE Most abundant in the body Bluish-gray, semitranslucent piable substance LOCALIZATION ADULT: Articular surface of bones, nose, larynx, ribs,trachea, bronchi.... YOUNG: Epiphyseal plate of the growing bones EMBRYO: Skeleton  HISTOGENESIS Mesenchymal connective tissue: cells congregate in chondrification centers Chondroblasts: aggrecans and type II collagen around themselves Chondrocytes + lacunae Division of chondrocytes: Isogenous groups INTER STICIA GROW L Isogenous group manufactured matrix TH enlarging the cartilage from within  HISTOGENESIS INTER STICIA GROW L TH Mesenchyma Centers of Chondroblasts and Chondrocytes + chondrofication EM lacunae  HISTOGENESIS PERICHONDRIUM Mesenchymal cells at the periphery differentiate to form fibroblasts Two layers: Outer fibrous layer Type I collagen, fibroblasts, blood vessels. Inner fibrous layer Mostly chondrogenic cells chondroblasts L ITIONA OS APP OWTH GR HISTOGENESIS  CARTILAGE CELLS Three types of cells.... Chondrogenic cells Spindel-shaped, narrow cells derived from mesenchymal cells Ovoid nucleus with one or two nucleoli Differentiation into both chondroblasts and osteoprogenitor cells Chondroblasts Two sources of chondroblasts: Mesenchymal cells of the center of chondrification Inner cellular layer of the perichondrium Plump and basophilic  CARTILAGE CELLS Three types of cells.... Chondrocytes Near the periphery are ovoid Deeper in the cartilage are more rounded Large nucleus with a prominent nucleoulus Lacuane = chondroplast Isogenous group: several chondrocytes Capsule of collagen fibers surrounds the lacunae : pericellular capsule. Chondron: isogenous group + capsule (structural unit of the cartilage) CARTILAGE CELLS CARTILAGE CELLS CARTILAGE CELLS EXTRACELLULAR MATRIX COLLAGEN Up to 40% of its dry weight in collagen (type II collagen) Mostly type II collagen but type IX, X and XI also present Proteoglyclans (aggrecans) Protein cores to which glycosaminoglycan molecules (chondroitin 4-sulfate, 6-sulfate and heparan sulfate) are linked Glycoproteins (chondronectin) Extracellular fluid  EXTRACELLULAR MATRIX TWO REGIONS Territorial matrix Around each lacuna Poor in collagen Rich in chondroitin sulfate (PAS+) Interterritorial matrix Bulk of the matrix Richer in type II collagen and poorer in proteoglycans Clearer due to the greater abundance of collagen fibers.  ELASTIC CARTILAGE Nearly identical to hyaline cartilage except for a network of elastic fibers Elasticity and ridigity Yellowish colour on gross observation. LOCATION pinna of the ear, auditory tubes, epiglottis and larynx.  ELASTIC CARTILAGE Differences with hyaline cartilage: More and larger chondrocytes and less abudant matrix  FIBROCARTILAGE NO perichondrium Type I collagen + fibroblasts Chondrocytes are in rows More acidophilic than hyaline or elastic cartilage (scarse proteoglycans) LOCATION intervertebral disks, pubic symphysis, articular disks and attached to bone.