Cartilage and bone
一、 Cartilage
一 .structure of cartilage tissue cartilage tissue = chondrocyte+ cartilage matrix
cartilage = cartilage tissue + perichondrium
1.chondrocyte • LM:
nucleus ， small ,round. 1-2
nucleolus; cytoplasm, basophilic.
• EM ：
rER and Gol. more ， Mi less.
• Function ： secrete cartilage matrix
2.cartilage lacuna Chondrocytes embedded in cartilage matrix form the space .
3.
isogenous cell group
：
A single parent chondrocyte divided into a group of cells(2-8) , in one cartilage lacuna.
4. cartilage matrix ＝ fibers ＋ ground substance cartilage matrix : secreted by chondrocytes ground substance ： proteoglycans . Glycosaminoglycan, water. form a meshwork.
5. cartilage capsule The matrix around the lacunae or the isogenous cell group, stains deeper than elsewhere.
二 . the types of cartilage tissue on characters of fibers in the matrix.
• Hyaline cartilage • fibrocartilage • Elastic cartilage
Hyaline cartilage • The matrix: transparent , homogeneous collagen
fibers , basophilic. • The chondrocytes: in surface , cells are small, resemble with fibroblasts ;inside , cells are large , present in groups. • Distribution : Costal cartilage , Articular cartilage, The walls of the trachea and large bronchi , etc.
Hyaline cartilage Perichondri um chondrocy te
matrix
Hyaline cartilage
Hyaline cartilage
Fibrocartilage • white cartilage . • The ground substance is less. type Ⅰcollagen
bundles , great tensile strength and elasticity. • The chondrocytes are smaller and located in line between the collagen bundles. • No perichondrium • Distributions: secondary cartilaginous joints or symphyses, etal.
fibrocartilage Collagen bundles chondrocyte matrix
Elastic cartilage • the matrix : numerous elastic fibers
,form a network. • Perichondrium covers the surface. • greater flexibility than hyaline cartilage. • Distributions: auricle, the wall of the medial part of the auditory tube , the epiglottis, etc.
Elastic cartilage chondroc yte Elastic fiber matrix
Elastic cartilage
三 . perichondrium The thin dense CT layer which capsuled the cartilage . outer layer ： collagen fibers ， protection.
inner layer ： more cells ， chondroblasts 、 blood vessels 、 lymphatic and nerves.
四 . How cartilage growth Tow kind of growth ： 1.appositional growth ： also called subperichondrium growth ， osteoprogenitor cells→ chondroblasts → chondrocytes.
2.interstitial growth ： growth in the cartilage .
二、 Bone
一 .Elements of bone
Bone matrix
Bone tissue
osteum
Bone marrow
Inorganic ions
Osteoprogenitor cells cells
bone
Organic matrix
osteoblasts osteocytes osteoclasts
二、 Osseous tissue （一）
bone cells
1. osteoprogenitor cell ： stem C →Osteoblasts chondroblasts
2. Osteoblasts ： protein secreting C →synthesize osteoid → bone matrix
3. osteocyte • most • small ， more processes. • lacuna ： osteocyte 。 • canaliculi ： delicate cytoplasmic processes of osteocyte 。
osteocyte
4. Osteoclast ： • few. • poly nucleus ， magakaryocytes. • EM ： ruffled border – microvilli • functions ：
lacuna
osteoblast
lamella
osteocyte
Osteoproge nitor cell osteoclast
Pattern of bone tissue
Bone cells osteoblas t osteocyte osteoclas t Mesenchy mal cell
（二） Bone matrix 1.constituents Collagen fiber
Organic matrix Ground substance ： 35%
glycosaminoglycans ,neutrophilic or acidic
Inorganic ions ： hydroxyapatite (Ca10 [PO4] 6[OH]2) 65%
2. Bone lamellus •thin plate of bone , collagen fibres & mineral salts ,deposited in a gelatinous ground substance. osseous fibres parallel or vertical. why? •Osteocyte: Embedded in bone matrix the same or between adjoining lamellae.
Relationships of osteocytes to bone lamellae
3. classifications • compact bone ： bone lamellae arranged dense, diaphysis of long bone, surface of short bones & flat bones. • spongy bone ： lamellae in the form of spicules ， trabecular network) 。 Epiphysis of long bone, surface of short bones & flat bones.
三、 structure of long bone
• long bone
Diaphysis: Compact bone Epiphysis: Spongy bone
•Surface: periosteum & articular cartilage • inside: marrow cavity.
Spongy bone
Articular cartilage Compact bone
periosteu m
Bone marrow
1. Diaphysis ： •Circumferential lamellae ： inner 、 outer. • Haversian system • interstitial lamellae
Outer Circumferential lamellae
Haversian system
interstitial lamellae
inner Circumferential lamellae
Haversian system • also called, osteon • concentric rings, Haversian lamellae, surround Central canal •Functions: Support , the basic unit.
Central canal
Interstitial lamellae
2. Epiphysis ： •Covered by a thin layer of compact bone . •Articular cartilage on the articular face.
3. osteum • periosteum: outer , inner. • endosteum • functions ： nutritive function 、 development and repair.
keypoints a. Structure of cartilage tissue. b. The characteristics of three kinds of c. d. e.
cartilage. How cartilage grow Bone cells and bone matrix Structure of long bone , esp , the structure of diaphysis.
三、 ossification self-study
！
Originate from mesenchyme… 。
（一） Formation of bone tissue Mesenchymal cell
osteoprogenitor cell
secre t
osteoblast
Fiber&GS （ osteoid ）
Translate into
Calcification
osteocyte
Bone matrix
Bone tissue
（二） manners of ossification 1. intramembranous ossification
mesenchyme
Embryonic membrane of CT
Flat bone
intramembranous ossification
2. endochondral ossification
mesenchyme
Rudiment of hyaline cartilage
long bone &irregular bone
endochondral ossification
• The wall of the shaft ： intramembra nous ossification, bone collar. • The center of the bone : endochondral ossification.
（三） growth of long bone Attribute to epiphyseal plate, continuous growth and replace. from epiphysis to diaphysis, epiphyseal plate ： ①zone of resting cartilage. ② zone of proliferating cartilage. ③ zone of calcification . ④ zone of ossification .