1. Dr. Ahmad Al-Taib Written by: Albara Marwa,, Abo Malik Group A leader
Cartilage
Dr. Ahmad Al-Taib
Written by:
Albara Marwa,, Abo Malik
Group A leader

2. What is cartilage?
It is a special type of connective tissue with a firm extracellular matrix.

3. Location Cartilage is found in: Respiratory tract External ear
Intervertebral disc
Articular surface of bones (in joints)
Skeleton of fetus

4. Components Cartilage consists of three components: Cells
Matrix (between the cells)
Perichondrium (outer layer)

5. Cartilage cells Cartilage contains three types of cells:
Chondrogenic cells
Chondroblast
chondrocyte

6. 1. Chondrogenic cells Originate from mesenchymal cells
Spindle shaped cells with oval nuclei
Found in the perichondrium
Differentiate into chondroblasts
(Differentiation of cells does not include cell division but only a change in structure)

7. 2.Chondroblasts Basophilic flat cells with flat nuclei
Protein-secreting cells
Secrete cartilage matrix
Found in the perichondrium
Originate from chondrogenic cells

8. 3. Chondrocyte
Each chondroblast secretes the matrix & becomes a chondrocyte with a large rounded nucleus.
The chondrocyte is the mature cartilage cell which also secretes matrix.
Each chondrocyte is situated in a small space called a lacuna surrounded by the matrix.
The chondrocyte can divide in the lacuna
There is no connection between the lacunae.

9. Cartilage Matrix
The matrix is an avascular extracellular material secreted by chondroblast & chondrocyte.
Cartilage matrix consists of:
Fibers: collagen type I or type II or elastic fibers.
Ground substance: glycoproteins & chondroitin sulphate.

10. Perichondrium
A dense vascular connective tissue on the surface of cartilage.
It consists of:
Outer fibrous layer of dens CT (Type I collagen).
Inner cellular layer of chondrogenic cells & chondroblast.
Its function is growth of cartilage

11. Types of cartilage
There are three types according to the fibers in the matrix:
Hyaline cartilage
Elastic cartilage
Fibrocartilage

12. Similarities between types of cartilage
All types have chondrocyte in lacunae.
All types have avascular matrix.
All types have perichondrium EXCEPT:
Fibrocartilage
Articular cartilage

13. Hyaline cartilage Found in:
Respiratory tract
Articular cartilage
Chondrocytes divide and form small groups called isogenous group.
Collagen type II in a basophilic matrix, but the collagen is not visible with the L.M.
The matrix is more basophilic near the chondrocyte.
Articular cartilage lacks perichondrium and it receives nutrient from the synovial fluid

14. Elastic cartilage
More chondrocytes and less matrix than hyaline cartilage.
Many elastic fibers in the matrix and in the perichondrium.
Collagen type II is also present
Examples: External ear & epiglottis.
Elastin stain stains elastin black

15. Fibrocartilage
Parallel bundles of acidophilic type I collagen fibers in the matrix.
(Note: Collagen type I is stronger than type II).
Chondrocytes form parallel rows.
Chondrocytes arise from fibroblasts.
More fibers and less chondrocytes than that in hyaline and elastic cartilage.
No perichondrium
Example: Intervertebral disc

16. Cartilage growth
Cartilage arises from mesenchyme during chondrogenesis
Cartilage grows by two methods:
Appositional growth : on surface from perichondrium.
Interstitial growth: deep in matrix.

17. Repair of cartilage Cartilage has a limited ability for repair.
Injured cartilage is replaced by Connective tissue.