Cartilage and bone lMechanic and supporting function lOrigin: embryonic mesenchyme lStructure: lcells (chondrocytes – in cartilage l osteocytes, osteoblasts, osteoklasts – in bone) lExtracellular matter §homogenous, amorphous substance §fibers (collagen or elastic – in cartilage, only collagen – in bone) Cartilage properties lAvascular tissue, without nerves, lDecreased reparative ability, regeneration from perichondrium lPerichondrium – dense collagen c. t. attached to cartilage linner chondrogenic layer louter c. t. layer Cell of cartilage lchondroblasts limmature chondrocytes in inner layer of perichondrium lchondrocytes – in cartilage lbasofilic cells → proteosynthesis, mitochondria, GER, Golgi apparatus, cytoskeleton. lproduce amorphous matrix and fibers. chondroblast lChondrocytes – isogenous groups, – lacunae, – basophilic capsule l of teritorial matrix l lIsogenous group + adjacent area of extra- cellular matter (territorial matter) = chondron schema cartilage4 Extracellular matter lCollagen II or I fibers lElastic fibers lGlykosaminoglycans –hyaluronic acid, chondroitin-sulphate lProteoglycans lGlykoproteins Types of cartilage lHyaline (hyalos=glass) – the most frequent, precursor of many bones in skeleton, covers articular surfaces, forms part of ribs skeleton of the nose, trachea, larynx lElastic - auricula, tuba auditiva, larynx, epiglottis lFibrocartilage - intervertebral discs, symphysis pubis, articular discs and meniscus l Hyaline cartilage, trachea, HE hyalinní chrupavka 1-Hyaline%20Cartilage%20-%20Trachea Elastic cartilage lelastic fibers in amorphous matrix; special staining: resorcin, fuchsin and orcein. lChondrocytes elastická chrupavka schema elastická chrupavka ccec3 Fibrocartilage lChondrocytes lThick bundles of collagenous fibers lmatrix lwithout perichondrium l fibrocart fibrocartilage 3 ccfts Bone lspecialized form of c. t. l l Bone tissue structure l lBone cells lExtracellular matrix l lOrganic – colagenos fibers l – amorphous matrix lInorganic – minerals l lPeriosteum § bone Bone tissue lPeriosteum – covers outer surface of bone: lInner layer (osteoblasts, fibroblasts) louter layer (only fibroblasts) lPeriosteum is attached by Sharpey‘s fibers. l lEndosteum – membrane with one layer of cells (osteoblasts, osteoclasts), covers inner surface of bone turned to the bone cavity) periosteum s2340x2 Bone cells losteoprogenitor cells – stem cells, in periosteum a endosteum losteoblasts produce organic matter, and transform into osteocytes osteoblasts Osteocyte lIn lakuna, lNumerous processes in canaliculi ossium (cell communication) l osteocyt v lakuně lemelozní kost Osteoclasts llarge cells (up to 100 µm), polynucleated cells (up to 50 N), arrise by fussion of monocytes lin Howship‘s lakuna llysosomal enzymes digest collagennous fibers cartilage resorption bay Bone matrix lcollagen fibers – collagen I (cca 90 % of org. matter) lamorphous matrix – osteoid. lstrength of matrix is caused by content of inorganic salts (hydroxyapatite). tropocollagen Types of bone tissue l2 types: /according to arrangement of collagen fibers/ lFibrillar (woven) bone – primary lLamellar bone – secondary lcompact – wall of long bone diaphysis, surface layer of epiphysis lspongy /trabecular/ – inner part of epiphysis § Lamellar bone lLamellae – thin plates with regularly arranged collagen fibers lHaversian systems - osteons lCircumferential lamellae louter linner lInterstitial lamellae l l bone Haversian system – osteon haversův systém bone Lamellar bone bon10gr bone tissue Haversian and Volkmann‘s canals bone%20structure Lamellar bone – spongy type Bone spongy lMatrix is also organized into the lamellae, but dont form Haversian systems. Lamellar bone – spongy, HE Spongiosní kost Histogenesis of bone tissue lEndochondral ossification – hyaline cartilage is model for bone (long bones) l l lIntramembranous ossification – mesenchyme membrane is model, mesenchymocetes differentiate into osteoblasts l(skull bone, part of mandibule and clavicula) l intramembranous__c Intramembranous ossification Endochondral ossification endochondral_oss_c_small endochondral%20ossification%201 Periosteal bone collar Undifferentiated cells in the perichondrium become osteoblasts, and the perichondrium is now the periosteum. endochondral%20ossification%202 Chondrocytes at the center of the growing (proliferating zone) cartilage model enlarge (zone of hypertrophy). The matrix calcifies (zone of calcification) and chondrocytes die. The rest of matrix form trabecular processes – spicules. Blood vessels penetrate cartilage and carry the osteoblasts from periosteum. Osteoblasts cover the spicules and produce osteoid (ossification zone). Ossification spreads in long axis of bone. endochondral%20ossification%203 Osteoclasts resorb primitive bone (zone of resorption) and medullary cavity is formed. Simillar process begins in epiphyses. Ossification spread radially. Also epiphyseal plates ossify at the end of body growth (cca 18 years). Endochondral ossification lZone of normal cartilage lZone of proliferated cartilage lZone of hypertrophic cartilage lZone of calcification lLine of erosion lZone of ossification lZone of resorption l ossifikace Image_000530A 7-Endochondral%20Ossification-Long%20bone 8-Endochondral%20Ossification-Long%20bone 11-Growth%20Plate-Endochondral%20Ossification 9-Endochondral%20Ossification-Long%20bone 6-Osteoclasts%20-%20Intramembranous%20Ossification Bone growth lcannot occur interstitally as cartilage growth does, because its rigid, mineralized matrix traps osteocytes and prevents them from dividing mitotically. Growth occurs in two directions: lin length, by maintenance and growth of epiphyseal plate of cartilage. These plates allow a bone to expand lengthwise. lin diameter, by continuous formation of bone around the periphery of the diaphysis. bone2 bone3 bone4 Periostal bone collar bone Image_000534 osifikace02 bone23 osifikace06 osifikace01 C0051202-Endochondral_ossification_in_human_fetus-SPL Normal hyaline cartilage Proliferating cartilage (growth) Hypertrophic cartilage Calcified cartilage * - calcified matrix LINE of EROSION spicules blood vessels osteoid osteoblasts * * B O N E Endochondral ossification 143_3 143%20osteoclast%203 143%20osteoclast%201 143%20osteoclast%202 osteoklasty 146%208 histo_SKELETAL_ossification_endochond_labeled a28113