1. 组织胚胎学课件 七年制英文医学班专用 中国医科大学 基础医学院 组胚 — 英文教学组

2. Chapter 4 Cartilage and Bone

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

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

5. 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

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

7. 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) chondronectin water ---fiber: type and number of fiber depends on the type of cartilage

8. 2) Classification: according to the fiber a. Hyaline cartilage: less collagenous fibril←type II collagen articular surface, rib cartilage, trachea and bronchi

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

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

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

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

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

14. 1) Bone tissue ① Cells:

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

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

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

18. ---function: ⅰ.synthesize bone collagen fiber and ground substance-osteoid ⅱ.release matrix vesicle: 0.1um in diameter membrane-coated ALPase(Alkaline phosphatase), ATPase and pyrophosphatase and phosphoester (phospholipid) calcium, crystal of bone salt and calbindin function: promote calcification

19. 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 regulate the balance of calcium and phosphonium

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

22. 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

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

24. glycoproteins: osteocalcin: involve in calcification of bone and regulate absorption of bone osteonectin: related to adherence between cell and bone matrix, regulate calcification of bone osteopontin

25. ---inorganic matter: bone salts Hydroxyapatite crystal: Ca 10 (PO 4 ) 6 (OH) 2 pin-shaped 10-20 nm longitudinal arranged *bone lamella: bone matrix arranged in layers at different direction

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

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

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

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

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

32. 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

33. 3) osteogenesis

34. ① basal processes --- formation : osteoprogenitor cell→ osteoblast → osteoid ↓ ↓calcification osteocyte + bone matrix bone tissue ---absorption: osteoclast →dissolve bone tissue→reconstruction

35. ② basal manner a. intramembranous ossification: ---CT membrane →osteoprogenitor cell → osteoblast→ossification center→bone trabeculae →thicker and longer ---flattened bone and irregular bone formed in these manner

36. b. endochondral ossification : e.g. long bone ⅰ.formation of cartilage model Mesenchymal cell→osteoprogenitor cell →chondroblast→chondrocyte→cartilage model( consists of hyaline cartilage and perichondrium) ⅱ.formation of bone collar osteoprogenitor cell (perichondrium) → osteoblast →bone tissue * These bone tissue surround the central segment of cartilage model as collar-shaped, so called bone collar

37. ⅲ.formation of primary ossification center and bone marrow cavity chondrocytes of model center stop differentiation, enlarge in size, calcification, dead →CT, BV in periosteum enter degenerating zone→osteoblast, osteoclast, osteoprogenitor cell and mesenchymal cell enter at same time→ossification→primary ossification center

38. primary bone marrow cavity(space between trabeculae) →bone marrow cavity

39. ⅳ.Formation of secondary ossification center and epiphyses secondary ossification center appears at the two end of long bone(epiphyses) epiphyseal plate: cartilage layer between epiphysis and bone shaft, growing zone

40. ③ Further growth of bone ---Become longer: by growth of epiphyseal plate from epiphyses to shaft, four zones can be seen: i. reserve cartilage zone: cell is small, round and basophilic ii. proliferating cartilage zone: cell is flattened, isogenous group cell arrange in single line

41. iii. calcified cartilage zone: cell become large, mature, round and degenerated, strong basophilic iv. ossification zone: ---become thicker: periosteum cell → osteoprogenitor cell→osteoblast