It is about fibers of Extracellular Matrix of Connective Tissues.

1. Collagen Fibers Fawad Mueen Arbi
Roll # 159

2. Introduction
 Most commonly occurring connective tissue
fibers.
 Most abundant protein in mammals (25-35% of
all proteins)
 Made up of collagen protein (Type I fibrils)
 These fibers are flexible but inelastic.
 Their diameter is 2-10 μm.
 Found in Cartilage, Bone, Tendon and
Ligament

3. Structure
 In LM, it appears interwoven running
randomly in all directions.
 When not under stress, they show wavy
pattern
 In EM, it shows collagen fiber is further
made of parallel fibrils which have diameter
of 50-90 nm.
 The gap between two collagen molecules
is called Lacunar Zone.

5. Collagen Fibers in
Tendon

6. Reticular fibers

7. introduction
 Much thinner than collagen fibers with diameter of 0.5-2 m.μ
 Made up of collagen protein (Type III fibrils)
 It is visualized by Silver staining and PAS staining.
 Also called Argyrophilic Fibers.
 Present in Lymph Nodes, Spleen, Liver, Endocrine Glands, Bone Marrow,
Endomysium and Endoneurium

8. production
 Bone Marrow and Lymph Nodes –
Reticular Cells
 Liver, Spleen, Endocrine Glands –
Fibroblasts
 Endoneurium – Schwann Cells
 GIT and Arteries – Smooth Muscle
Cells

9. Reticular Fibres in
Spleen