Specialized connective tissue Rigid Elastic Resilient RESISTS COMPRESSION

• Specialized connective tissue • Rigid, Elastic, Resilient RESISTS COMPRESSION • AVASCULAR – nutrients diffuse through matrix

Hundreds of Eyes Staring Back at YOU!

PERICHONDRIUM n n n Dense irregularly arranged connective tissue (type I collagen) Ensheaths the cartilage Houses the blood vessels that nourish chondrocytes

CHONDROBLAST n n Progenitor of chondrocytes Lines border between perichondrium and matrix Secretes type II collagen and other ECM components Chondroblasts build

CHONDROCYTE Mature cartilage cell n Reside in a space called the lacuna n Clear areas = Golgi and lipid droplets n

n n n Chondrocytes completely fill their lacunae RER and euchromatic nuclei Synthetically active, secrete matrix N RER Cartilage matrix

MATRIX n n Provides the rigidity, elasticity, & resilience FIBERS ¨ n Collagenous and elastic GROUND SUBSTANCE Glycosaminoglycans (chondroitin sulfates, keratin sulfate, hyaluronic acid) ¨ Proteoglycans: GAGs + core protein ¨ Water ¨ n n Basophilic Territorial matrix - high [ ] of sulfated proteoglycans

CARTILAGE GROWTH n Appositional ¨ Increasing in WIDTH; chondroblasts deposit matrix on surface of preexisting cartilage n Interstitial ¨ Increasing in LENGTH; chondrocytes divide and secrete matrix from w/in lacunae

Cartilage n Embryo ¨ More prevalent than in adult ¨ Skeleton initially mostly cartilage ¨ Bone replaces cartilage in fetal and childhood periods

Location of cartilage in adults External ear n Nose n “Articular” – covering the ends of most bones and movable joints n “Costal” – connecting ribs to sternum n Larynx - voice box n

Epiglottis – flap keeping food out of lungs n Cartilaginous rings holding open the air tubes of the respiratory system (trachea and bronchi) n Intervertebral discs n Pubic symphysis n Articular discs such as meniscus in knee joint n

Remember the four basic types of tissue… ¨Epithelium ¨Connective tissue n Connective tissue proper n Cartilage n Bone n Blood ¨Muscle tissue ¨Nervous tissue

cartilage

Cartilage is connective tissue n n Cells called chondrocytes Abundant extracellular matrix ¨ Fibers: (hyaline cartilage) collagen & elastin ¨ Jellylike ground substance of complex sugar molecules ¨ 60 -80% water (responsible for the resilience) ¨ No nerves or vessels

TYPES OF CARTILAGE n HYALINE n ELASTIC n FIBROUS

Types of cartilage: 3 1. Hyaline cartilage: flexible and resilient ¨ ¨ ¨ 2. Elastic cartilage: highly bendable ¨ ¨ 3. Chondrocytes appear spherical Lacuna – cavity in matrix holding chondrocyte Collagen the only fiber Matrix with elastic as well as collagen fibers Epiglottis, larynx and outer ear Fibrocartilage: resists compression and tension ¨ ¨ Rows of thick collagen fibers alternating with rows of chondrocytes (in matrix) Knee menisci and annunulus fibrosis of intervertebral discs

HYALINE CARTILAGE n FUNCTION Support tissue and organs ¨ Model for bone development ¨ n MATRIX Type II collagen (thin fibrils) ¨ Chondroitin sulfate, keratin sulfate, hyaluronic acid ¨ Water ¨ n LOCATION ¨ Tracheal rings, nasal septum, larynx, articular

Hyaline Cartilage

ELASTIC CARTILAGE n FUNCTION ¨ n MATRIX ¨ n Normal components of hyaline matrix plus ELASTIC fibers LOCATION ¨ n Support with flexibility External ear, external auditory canal, epiglottis STAINS ¨ Elastic fibers stain BLACK with Weigert stain perichondrium

Elastic Cartilage

FIBROCARTILAGE n FUNCTION ¨ Support with great tensile strength n MATRIX ¨ Type I collagen Oriented parallel to stress plane n LOCATION ¨ Intervertebral disks, pubic symphysis

FIBROCARTILAGE n n Chondrocytes align between collagen fibers Collagen fibers lie parallel to lines of stress

Fibrocartilage

Locations of the different kinds of cartilage

Before we look at collagen pic… n Hyaline cartilage: flexible and resilient ¨ Chondrocytes appear spherical ¨ Lacuna – cavity in matrix holding chondrocyte ¨ Collagen the only fiber n Elastic cartilage: highly bendable ¨ Matrix with elastic as well as collagen fibers ¨ Epiglottis and larynx n Fibrocartilage: resists compression and tension ¨ Rows of thick collagen fibers alternating with rows of chondrocytes (in matrix) ¨ Knee menisci and annulus fibrosis of intervertebral discs

Triple helix of collagen molecules form fibril Fibrils aggregate into collagen fibers

Growth of cartilage n Appositional ¨ “Growth from outside” ¨ Chrondroblasts in perichondrium (external covering of cartilage) secrete matrix n Interstitial ¨ “Growth from within” ¨ Chondrocytes within divide and secrete new matrix n n Cartilage stops growing in late teens (chrondrocytes stop dividing) Regenerates poorly in adults

Uploaded By. . M. FARRUKH FAYYAZ