Histology of cartilage Introduction Modified solid type of

Histology of cartilage

Introduction • Modified (solid type) of connective tissue. • Forms the skeletal basis of some parts of the body. • Avascular • E. g. Auricle of the ear, lower part of the Histology of cartilage 2

Components Cell s Chondrocy tes Matrix • Fibers • Collagen OR • Elastic fibers • Ground substance Histology of cartilage • Tissue fluid • GAG & 3

Chondrocytes • Derived chondroblast • Chondroblast mesenchymal cell • Seen in spaces lacunae Histology of cartilage 4

3 types of cartilage 1. Hyaline cartilage 2. Elastic cartilage 3. Fibrocartilag Histology of cartilage 5

Histology of cartilage 6

Matrix (fibers + ground substances) • Type II collagen fibers • Proteoglycans, Hyaluronic acid • Capsule or territorial matrix • Interterritorial matrix • Lacunae (tiny spaces in the matrix) • Isogenous cell nest / CELL NESTS (offspring of a common parent cell). Histology of cartilage 7

Seen under microscope Histology of cartilage 8

Hyaline cartilage Fibrous layer Chondrogenic layer Perichondrium Chondroblasts Cell nest Matrix Chondrocyte in lacuna

Hyaline cartilage- magnified Terretorial matrix Interterretorial matrix Chondrocyte in lacuna Cell nest

Distribution – Costal cartilage – Articular cartilage – Thyroid, cricoid, arytenoid – Tracheal rings – Part of nasal septum – Epiphyseal plate Histology of cartilage 11

Elastic cartilage (yellow fibrocartilage) • Greater flexibility. • Ground substance contains abundance of branching and anastomosing elastic fibres. • No isogenous cell nests. • Chondrocytes are found in single or in small groups. Histology of cartilage 12

Elastic cartilage Histology of cartilage 13

Elastic cartilage (microscopic view) Histology of cartilage 14

Elastic cartilage Chondrogenic layer Fibrous layer Perichondrium Chondroblast Matrix with elastic fibers Chondrocyte in the lacuna

Distribution • Auricle & lateral part of the external acoustic meatus. • Medial part of auditory tube. Histology of cartilage 16

• Epiglottis, corniculate, cuneiform, apical Histology of cartilage 17

White fibrocartilage It is intermediate between Dense connective tissue and hyaline cartilage (tensile strength) Chondrocytes are found in singles or in rows with bundles of collagen with little matrix. No perichondrium. Bundles of collagen (type 1) Histology of cartilage 18

White fibrocartilage Histology of cartilage 19

White fibrocartilage (microscopic view) Histology of cartilage 20

White-fibro cartilage Chondrocyte Matrix

Distribution • Secondary cartilaginous joints – intervertebral discs, – pubic symphysis. Histology of cartilage 22

• Articular discs Histology of cartilage 23

• Menisci of the knee joint Histology of cartilage 24

Growth of Cartilage • Interstitial Growth ? ? • Appositional Growth? ? Histology of cartilage 25

Histology of cartilage 26