Cartilage functions to form the supporting framework of organs, articulate bone surfaces, and template long bone growth. It develops from mesenchymal cells and lacks blood vessels and nerves. Cartilage has a perichondrium layer and an extracellular matrix containing collagen, elastic fibers, proteoglycans, and water. The three main types are hyaline, elastic, and fibrocartilage, which differ in matrix composition and collagen content, providing different structural roles.

1. ;
CARTILAGE
FUNCTIONS
● Form the supporting framework of organs
● Form articulating surfaces of bones
● Form the template for the growth and development of long bones and most of the rest of the
fetal skeleton
CHARACTERISTICS
● Develops from mesenchymal cells
● Avascular (secretes anti-angiogenesis factor - substance that prevents blood vessel growth)
● Aneural (lacks nerves)
CARTILAGE COMPONENTS
PERICHONDRIUM CELLS EXTRACELLULAR MATRIX
● Found on peripheries of hyaline and elastic cartilage
except articular hyaline cartilage of long bones and
fibrocartilage
PERIPHERAL (OUTER) LAYER/ FIBROUS LAYER
● Separates cartilage from other tissues
● Vascularized, DICT with type I collagen
● Contains fibroblasts - produces collagen fibers
● Contains blood vessels and nerves
INNER LAYER/ CHONDROGENIC LAYER/ CELLULAR LAYER
● Gives rise to future chondrocytes
● Gives rise to chondroblasts
● Cartilage cells: chondroblasts (produces fibers + ground
substance (ECM) of cartilage)
o Found in the outer layer of cartilage under the
perichondrium
o Main function: create new cartilaginous tissue
● Chondrocytes - matured chondroblasts that are entrapped
to the matrix they produce
o As cartilage grows. Chondrocytes divide and
cluster together to form lacunae (space that
chondrocytes occupy within the cartilage)
o function: maintain cartilaginous tissue
● Collagen and elastic fibers (depending on collagen type)
o Provides strength
● Type 2 Collagen predominates
o Highly refractile
● Proteoglycans, notably aggrecan
o Aggrecan contains numerous chondroitin
sulfate (enables cartilage to deform their shape;
allows resilience; withstand mechanical stress
compression forces)
● High content of bound water allows cartilage to serve as a
shock absorber

2. CARTILAGE TYPES
PARAMETER HYALINE ELASTIC FIBROCARTILAGE
Important
information
● Derived from the greek word hayalus = glass
● Most common
● Provides a firm structural and flexible support
● In embryo - forms the temporary skeleton that is
gradually replaced by bone
● Territorial matrix - darker matrix immediately
around chondrocytes
● Interterritorial matrix - less intensely stained area
between the isogenous groups of chondrocytes
● Lacunae - contains mature chondrocytes
● Better flexibility than hyaline ● type 1 collagen fibers - strongest and toughest
type
Main features of the
extracellular matrix
● Homogeneous (because the type 2 collagen fibrils
present have the same refractive index as that of
ground substance), with type II collagen and
aggrecan
● Rich in ground substance
● Bluish, basophilic
● Few elastic fibers
● Type II collagen, aggrecan, and darker elastic
fibers
● Numerous elastic fibers - visualized using silver
stain
● Type II collagen and large areas of dense regular
connective tissue with type I collagen
● Thick type 1 collagen fibers predominate, hence
hyaline cartilage matrix not that visible
Major cells ● Chondrocytes, chondroblasts ● Chondrocytes, chondroblasts ● Chondrocytes, fibroblasts
Typical arrangement
of chondrocytes
● random/Isolated or in abundant isogenous groups
● Small chondrocytes
● Usually in less isogenous groups
● Big chondrocytes
● Isolated or in isogenous groups arranged axially
● Small chondrocytes usually distributed in rows
Presences of
perichondrium
● Yes (except at epiphysis and articular cartilage) ● Yes ● No Perichondrium
Main locations of
examples
● Trachea, ribs, nose larynx
● Many components of upper respiratory tract;
articular ends and epiphyseal plates of long bones;
fetal skeleton
● EEEE: External ear, external acoustic meatus,
eustachian tubes, auditory tube, epiglottis and
certain other laryngeal cartilages
● PIA: Pubic symphysis, Intervertebral discs,
attachments of certain ligaments, meniscus, and
certain other joints; insertions of tendons
Main functions ● Provides smooth, low-friction surfaces in
joints; structural support for respiratory tract,
resilient cushion, resists compressive stress
● Provides flexible shape and support of soft
tissues
● Provides cushioning, tensile strength, and
resistance to tearing and compression
Laboratory Slides