Dr. Archana Rani Associate Professor Department of Anatomy KGMU UP, Lucknow

1. Dr. Archana Rani Associate Professor Department of Anatomy KGMU UP, Lucknow 2.12.2014

2. CARTILAGE Modified connective tissue Forms skeletal basis of some parts of body Matrix is firm giving it the characteristic consistency Resists compression Avascular (nutrients diffuse through matrix) Perichondrium is rich in blood vessels

3. PERICHONDRIUM Dense irregularly arranged fibrous tissue Ensheaths the cartilage Composed of cells & matrix Matrix consists of fibres & ground substance Houses the blood vessels that nourish chondrocytes Present in most of the hyaline & elastic cartilage Absent in fibrocartilage Fibrous layer Cellular layer

4. CHONDROBLAST Mesenchymal (embryologically) Progenitor of chondrocytes Lines border between perichondrium and matrix Produce the intercellular matrix and collagen fibres Cells which become imprisoned within this matrix become chondrocytes.

5. CHONDROCYTE Mature cartilage cell Reside in a space called the lacuna Isogenous cell group Basophilic Clear areas = Golgi and lipid droplets

6. CHONDROCYTE N RER Cartilage matrix Chondrocytes completely fill their lacunae RER and euchromatic nuclei Synthetically active, secrete matrix Synthesize type II collagen, proteoglycans and chondronectin.

7. MATRIX Provides the rigidity, elasticity, & resilience FIBERS Collagenous and elastic GROUND SUBSTANCE Glycosaminoglycans (chondroitin sulfates & keratan sulfate) Proteoglycans Water Basophilic Territorial matrix Interterritorial matrix

8. CARTILAGE GROWTH Interstitial Newly formed cartilage grows by multiplication of cells throughout its substance. Appositional Addition of new cartilage over the surface of existing cartilage.

9. TYPES OF CARTILAGE HYALINE ELASTIC FIBROUS

10. CARTILAGE: LOCATIONS

11. HYALINE CARTILAGE • Sites: Tracheal rings, nasal septum, larynx, costal cartilage & articular surfaces of joints • Cartilage cells: Present singly or in groups of 2 or 4 cells inside lacunae • Cartilage Matrix: Collagen type II • Ground substance: Homogenous, clearly basophilic • Functions: supportive

13. ELASTIC CARTILAGE Sites: Auricle, ext. auditory meatus, auditory tube, epiglottis, apices of arytenoid cartilage Cartilage cells: larger, more numerous, packed more closely Cartilage Matrix: elastic fibres, collagen type II Ground substance: Rich in elastic fibres Functions: supportive with resilience Elasticfibers stain with orcein.

14. FIBROCARTILAGE Intervertebral disc • Sites: intervertebral discs, arytenoid cartilage (except apices), pubic symphysis, manubriosternal joint, articular disc of TM joint. • Cartilage cells: fewer, smaller, scattered singly or in rows • Cartilage Matrix: collagen type I & II • Ground substance: acidophilic • Functions: supportive with tensile strength

16. Clinical application Osteoarthritis Pseudoachondroplasia

17. bonE Modified connective tissue Highly vascular mineralized connective tissue consisting of cells and dense intercellular organic matrix impregnated with inorganic salts. Provide support & protection to the vital organs Forms skeletal framework

18. Articular cartilage Spongy bone Periosteum Marrow cavity Compact bone (location of haversian systems)

19. Composition • Cells: • Osteogenic cells • Osteoblasts • Osteocytes • Osteoclasts • Fibers: collagen type I • Ground Substance: Proteoglycans & glycoproteins

20. The matrix of bone is a mixture of organic (collagen) and inorganic (calcium phosphate) 90% of bone is matrix, with the remaining 10% made of osteocytes.

21. Microscopic Anatomy of Bone Figure 5.3

22. Lamellar arrangement • Lamellae • Rings around the central canal • Sites of lacunae • Lacunae • Cavities containing bone cells (osteocytes) • Arranged in concentric rings Figure 5.3 Slide 5.11a

23. Lamellar arrangement • Canaliculi • Tiny canals • Radiate from the central canal to lacunae • Form a transport system Figure 5.3 Slide 5.11b

24. compact bone The morphofunctional unit of the bone is osteon, or Haversian system. Lamellar pattern of compact bone: Haversian system Interstitial lamellae Circumferential lamellae

26. T.S. through compact bone ‘Haversian Systems’

27. Dark spots are called ‘lacunae’ and would contain osteocytes in living bone Central canal containing an artery, vein, lymph vessel and nerves

28. What happens when excessive bending force compresses the bone…! compression force

29. Clinical application Scurvy Rickets Osteomalacia Osteoporosis Osteogenesis imperfecta Pseudoachondroplasia

30. Save your bones

31. Take home message Aerobic exercises Low impact, weight bearing exercises Resistance exercises

32. References 1. diFiore’s Atlas of Histology with functional Correlations, 12th Edition. 2. Essentials of Anatomy for Dentistry Students,1st Edition. 3. Textbook of Histology, 3rd Edition.

33. MCQ • Fibrous cartilage is present in: • Auricle • Nose • Tracheal rings • Intervertebral discs

34. Label the following A B C Don’t confuse this picture with the Liver Lobule!

35. MCQ • Elastic cartilage is present in: • Apices of arytenoid cartilage • Epiphysis • Tracheal rings • Temporomandibular joints

36. MCQ • Hyaline cartilage is present in: • Tracheal rings • External auditory meatus • Semilunar cartilages of knee joint • Intervertebral discs

37. MCQ The blood vessels and nerves go inside the compact bone through: 1. Haversian canal 2. Volkman’s canal 3. Canaliculi 4. Interstitial lamellae