1. Cartilage and Bone

2. 1. Cartilage: organ=Cartilage tissue+perichondrium

3. 1) structure of cartilage tissue ---cell: chondrocyte ---cartilage matrix

4. ① chondrocyte: ---Structure: LM embedded in cartilage lacuna peripheral cells: --small and immature --single and flattened central cell: --large and mature, --round and in group of 2-8 cells --small and round nucleus --basophilic cytoplasm --EM: rich in RER and Golgi complex

5. *isogenous group: several cells locates in one lacuna, which are derived from a single(same) parent cell

6. ② Cartilage matrix ---ground substance: proteoglycan: --same to loose CT --there are more chondroitin sulfate distributed at the periphery of cartilage lacuna---called as cartilage capsule(basophilic) water ---fiber: type and number of fiber depends on the type of cartilage

7. 2) Classification: according to the fiber a. Hyaline cartilage: less collagenous fibril articular surface, rib cartilage, trachea and bronchi

8. b. Fibrous cartilage: large amount of collagenous fiber bundles cells are small and less intervertebral disc, symphysis pubis

9. c. Elastic cartilage: large amount of elastic fiber external ear, epiglottis

10. 3) perichondrium two layers: ---out layer: contain more fiber-protection ---inner layer: more cells-osteoprogenitor cell(fusiform in shape)

11. 4) growth of cartilage ---interstitial growth: inner chondrocyte proliferation→ produce fiber and matrix. immature cartilage ---appositional growth: osteoprogenitor cell→chondroblast → chondrocyte → produce fiber and matrix. growing and mature cartilage

12. 2.Bone ---consists of bone tissue, periosteum and endosteum, bone marrow

13. 1) Bone tissue ① Cells:

14. a. osteoprogenitor cell: stem cell ---structure: fusiform, small ovoid nucleus slight basophilic cytoplasm exist in periosteum and endosteum ---function: differentiated into osteoblast and chondrocyte

15. b. osteoblast : ---structure: LM: single layer of cuboidal or low columnar cell round nucleus basophilic cytoplasm located on the surface of bone tissue

16. EM: fine processes rich in RER, Golgi complex

17. ---function: ⅰ.synthesize bone collagen fiber and ground substance-osteoid ⅱ.release matrix vesicle: 0.1um in diameter membrane-coated function: promote calcification

18. c.osteocyte ---structure: flattened cell with multiple long thin processes located in bone lacuna and bone canaliculus basophilic cytoplasm adjacent cells connect in bone canaliculus by gap junctions ---function: Maintain bone matrix

20. d. osteoclast ---structure: LM: multinuclear large cell, 30-100um 6-50 nuclei acidophilic cytoplasm located at peripheral part of bone

21. EM: ruffled border-processes light zone: --under the ruffled border --microfilament primary lysosome, pinosome and secondary lysosome RER, mito. and Golgi ---function: dissolve and absorb bone matrix

22. ② Bone matrix ---organic matter: bone collagen fiber -collagenous fiber (type I collagen) ground substance: glycosaminoglycan

23. ---inorganic matter: bone salts Hydroxyapatite crystal: Ca 10 (PO 4 ) 6 (OH) 2 pin-shaped longitudinal arranged *bone lamella: bone matrix arranged in layers at different direction

24. 2) Architacture of long bone Long bone is an organ, made up of bone tissue(shaft and epiphyses), periosteum and endosteum, bone marrow

25. ① shaft: consists of compact bone a. circumferential lamella: /outer concentrically-arranged /inner around inner surface of bone

26. b. Haversian system (osteon): /cylindric structure, 3-5mm /central canal: N, BV, CT /Haversian lamella: 4-20 layers

27. c. interstitial lamella: /irregular lamella /remnant of Haversian or circumferential lamella *perforating canal: /transverse canal /connect with Haversian canal

28. ② epiphyses: composed of spongy bone ---trabeculae: formed by parallelly-arranged lamella form a spongy-liked network ---Bone marrow: hemopoietic tissue

29. ③ periosteum and endosteum: CT membrane ---periosteum: DCT outer layer:more fiber bundles form perforating fiber inner layer: rich in BV, N and osteoprogenitor cells ---endosteum: thin, a layer of osteoprogenitor cell and CT ---function: provide nutrition and osteoblast for bone growth and repairing

30. 3) osteogenesis Self study!