Cartilage consists of cells (chondrocytes) and an extensive extracellular matrixcomposed of fibers and ground substance.3 forms of cartilage have evolved, eachexhibiting variations in matrix composition:

1. Hyaline cartilage2. Elastic cartilage3. Fibrocartilage

1. Hyaline cartilage: in the articular surfaces of themovable joints; the walls of larger respiratorypassages (nose, larynx, trachea, bronchi); theventral ends of ribs; and in the epyphysealplates of bones

2. Elastic cartilage: in the auricle of the ear; thewalls of the external auditory canals, theauditory tubes, the epiglottis, and the cuneiformcartilage in the larynx

3. Fibrocartilage: in the intervertebral disks; and inarticular menisci

Perichondrium: outer layer (stratum fibrosum) type I collagen, inner layer (stratum

chondroblasticum) rich of cellsThe unit of cartilages: chondronChondrocyte: only one cell, or little groups ofcells, roundish shape, spherical nucleus

In hyaline cartilage: 2-4 chondrocytesIn elastic cartilage: 1-2 chondrocytesIn fibrous cartilage: 1 chondrocyte

LacunaPericellular matrixTerritorial/capsular matrixInterterritorial matrix

Schematic representation of hyaline cartilage

territorial/capsular matrix

chondron

chondrocyteinterterritorialmatrix

lacuna

perichondrium

pericellular matrix

Slide 7, Hyaline cartilage (HE), 10X

perichondriumstratum fibrosum

stratum chondroblasticum

interterritorial matrix

chondrons

chondrocytes

territorial matrix

chondron

lacuna

Slide 7, Hyaline cartilage (HE), 40X

pericellular matrix

interterritorial matrix

To identify the parts of hyaline cartilage:perichondriumchondronchondrocytepericellular matrixterritorial matrixinterterritorial matrixlacuna

Slide 8, ear (orcein+H), 10X

perichondrium

perichondrium

chondrons

elastic fibers

chondrocytes

chondron

Slide 8, ear (orcein+H), 40X

To identify the components of the elasticcartilage:elastic fiberchondronchondrocyte

Slide 9, Articular menisc (HE), 40X

collagen fibers

chondrocytes

To identify the parts of the fibrocartilage:chondrocytescollagen fibers

cancellous(spongy) bone

Inner circumferentiallamellae

compact bone

outer circumferential lamellaeHaversian system (osteon)

osteocyteHaversiancanal

Volkmann scanal

Schematic drawing of the bone

Slide 10, Bone (ground section) 10X

Haversian canalVolkmann s canal

inner circumferential lamellae

outer circumferential lamellae

osteocytes

interstitial lamellae

osteon

Haversian canal

osteocytes

Slide 10, Bone (ground section) 40X

osteon

To recognize the following structures:osteonouter and inner circumferential lamellaeinterstitial lamellaeosteocyteVolkmann s canalHaversian canal

Enchondralossification

Slide 11, Enchondral ossification (HE) 4X

enchondral ossification

skeletal muscle

bone spicules

bone marrow

bone marrow

bone spicule ossification zone

hypertrofic cartilage zone

proliferative zone

resting zone

Slide 11, Enchondral ossification (HE) 10X

To identify:enchondral ossification with its zonesbone marrowbone spiculesskeletal muscleadipose tissue