There are four main types of tissue: epithelial, connective, nervous, and muscular. Connective tissue forms a matrix beneath epithelial layers and supports organs. It is composed of cells and an extracellular matrix containing fibers and ground substance. There are several classes of connective tissue including true connective tissue which is divided into loose tissues like areolar and adipose tissue, and dense tissues like tendons.

1. Basic tissue types
Epithelial tissue.
Connective tissue.
Nervous tissues.
Muscular tissue.

2. • Is a term used to describe the tissue that forms a matrix beneath the epithelial
layer and is a connecting or supporting framework for most of the organs of the
body.
Epithelial tissues line the outer surfaces of
organs and blood vessels throughout the
body, as well as the inner surfaces of
cavities in many internal organ
Def.

3. Connective tissue
o Is formed of :
1. cells.
2. extracellular matrix.
 fibers.
 ground substance.
Cells
fibers Ground
substance
C.T
Extracellular
matrix

4.  Form capsule of organs & internal architecture.
 Form tendons and ligaments.
 The areolar tissue fills spaces between organs.
 The bone and cartilage support the body.
 Adipose tissue support & store fat.
 Defense mechanism (phagocyte - antibodies).
Connective tissue

6. Cells of C.T:
A. Structural:
1. Fibroblasts
2. Chondroblasts
3. osteoblasts.
4. Ground substance
B. Immunologic:
1. plasma cells
2. Macrophages
3. mast cells
4. leucocytes.
C. Energy storing cells:
1. fat cells.
‫نوع‬ ‫حسب‬ ‫على‬ ‫التقسيم‬
‫الخليه‬

7. 1. Fibroblasts
Connective tissue
A. Structural
• They are the most common cells in connective tissue.
• They synthesize fibers and ground substance.
• Can be active or quiescent.
• Rarely undergo division in adults.

8. Fibers
• C.T fibers are:
I. Collagen fibers.
II. reticular fibers.
III. Elastic fibers.
Connective tissue fibers are polymerized elongated proteins.
Collagen and reticular fibers are formed by protein collagen.
While elastic fibers are formed by protein elastin.

9. Fibers - Collagen fibers
• Is the most abundant protein in the body(30%).
• A family of > 27 members.
• Distinguished by their molecular morphology, function, distribution,,,,
• Designated by Latin numbers; I, II, III,…
Fibers are formed of fibrils which are composed of microfibrils that are visible only by
electron microscope.

10. Fibers - Reticular fibers
 Consist mainly of collagen type III.
 Thin fibers.
 Form extensive network in certain organs.
 Not visible by H&E stains.
 Stain black in silver stains.
 Found in smooth muscle, arteries, endocrine glands, spleen, liver,…

11. They are colored yellow in fresh preparations.
Need special stains.
Formed of individual microfibrils.
Composed of protein elastin.
Can be stretched (150%).
Fibers - Elastic fibers

12.  Fill the spaces between cells and fibers of the CT.
 It is viscous and acts as lubricant and barrier.
 Formed of 3 components:
A. Proteoglycans.
B. Glycoproteins.
C. Tissue fluids.
Fibers - Ground substance

13. TYPES OF CONNECTIVE
TISSUE
1. True Connective Tissue (proper)
I. Loose Connective Tissue
II. Dense Connective Tissue
2. Supportive Connective Tissue
 Cartilage
 Bone
3. Liquid Connective Tissue
• Blood
‫نوع‬ ‫حسب‬ ‫على‬ ‫التقسيم‬
‫النسيج‬

14. Classes of Connective Tissue

15. 1. True or Proper Connective Tissue
TYPES OF CONNECTIVE
TISSUE
I. Loose Connective Tissue
A. Areolar tissue B. Adipose tissue C. Reticular CT
Widely distributed
under epithelia
Hypodermis, within abdomen,
breasts
Lymphoid organs such as lymph
nodes

16. 1. True or Proper Connective Tissue
TYPES OF CONNECTIVE
TISSUE
I. Loose Connective Tissue
A. Areolar tissue
• consists of : all 3 types of fibers, several types of cells, and semi-fluid ground substance
• found in : subcutaneous layer and mucous membranes, and around blood vessels, nerves and organs
• function : strength, support and elasticity

17. 1. True or Proper Connective Tissue
TYPES OF CONNECTIVE
TISSUE
I. Loose Connective Tissue
B. Adipose tissue
• consists of : adipocytes; "signet ring" appearing fat cells. They store energy in the form of triglycerides (lipids).
• found in : subcutaneous layer, around organs and in the yellow marrow of long bones
• function : supports, protects and insulates, and serves as an energy reserve

18. 1. True or Proper Connective Tissue
TYPES OF CONNECTIVE
TISSUE
I. Loose Connective Tissue
C. Reticular tissue
• Consists of : fine interlacing reticular fibers and reticular cells
• Found in : liver, spleen and lymph nodes
• Function : forms the framework (stroma) of organs and binds together smooth muscle tissue cells

19. 1. True or Proper Connective Tissue
TYPES OF CONNECTIVE
TISSUE
II. Dense Connective Tissue
A. Dense regular connective tissue B. Dense irregular connective tissue
Tendons and
ligaments
Dermis of skin , submucosa of
digestive tract

20. 1. True or Proper Connective Tissue
TYPES OF CONNECTIVE
TISSUE
II. Dense Connective Tissue
A. Dense regular connective tissue
• consists of : bundles of collagen fibers and fibroblasts
• forms : tendons, ligaments and aponeuroses
• Function : provide strong attachment between various structures

21. 1. True or Proper Connective Tissue
TYPES OF CONNECTIVE
TISSUE
II. Dense Connective Tissue
B. Dense Irregular connective tissue
• consists of : randomly-arranged collagen fibers and a few fibroblasts
• Found in : fasciae, dermis of skin, joint capsules, and heart valves
• Function : provide strength