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HISTOLOGYOF
CONNECTIVE TISSUE
BY
DR. MUDASSAR ALI ROOMI (MBBS, M. Phil.)
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LOOSE CONNECTIVE TISSUE
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DENSE CONNECTIVE TISSUE:
FEATURES:
Close packing of fibers
Fewer cells than loose C.T Lesser ground substance
Less flexible
Resistant to stress
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TRUE OR PROPER CONNECTIVE TISSUE
DENSE CONNECTIVE TISSUE:
according to arrangement of fibers it is of two
varieties:
a. Dense regular connective tissue Tendons
ligaments
aponeurosis
b. Dense irregular connective tissue
Dermis of skin, submucosa of digestive tract
Capsule of liver, spleen and glands
Joint capsules
Heart valves
Perichondrium
Periosteum
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Dense Connective Tissue
contains more numerous
and thicker fibers and far
fewer cells than loose CT.
1. DENSE REGULAR
CONNECTIVE TISSUE
± consists of bundles of collagen fibers are denselypacked and running parallel
to each other
± fibroblasts are thepredominant cell
± Function = provide strongattachment between variousstructures
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DENSE REGULAR CONNECTIVE TISSUE
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Tendons: have bundles of collagen fibers.
Aponeurosis: have several superimposed
layers of collagens fibers. Ligaments: just like tendon in histology. White
and yellow (elastic) ligaments.
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APONEUROSIS
Flat and relatively thin
sheet of collagen fibers
e.g. bicipital
aponeurosis
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Yellow elastic ligaments
Examples of yellow elastic ligements:
1. Ligamentum nuchae
2. True vocal cords3. Ligamentum flavum of vertebral column
4. Suspensory ligament of penis.
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DENSE IRREGULAR CONNECTIVE TISSUE:
± consists of randomly-arranged collagen fibers and a few fibroblasts
± Fewer other cell types
± minimal ground substance just like dense regular C.T
± Collagen fibers exhibit random orientation and provide strong
tissue support
± Concentrated in areas where resistance to forces from different
directions is needed
± Function = provide strength
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DENSE IRREGULAR CONNECTIVE TISSUE
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FUNCTIONS OF CONNECTIVE TISSUE
To connect the various structures with each othere.g. tendon.
Mechanical support to tissue e.g dermis of skin.
Exchange of nutrients through the ground substance.
Defense function is provided by:
1. Barrier made by the intercellular substance
2. Macrophages
3. Plasma cells
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GROUND SUBSTANCE
The ground substance of the ECM is a highlyhydrated, transparent, complex mixture of macromolecules, principally in three classes:
GAGs, proteoglycans, and glycoproteins. The complex molecular mixture of the ground
substance is transparent and rich in bound water.
It fills the space between cells and fibers of
connective tissue and, because it is viscous,
acts as both a lubricant and a barrier to thepenetration of invaders.
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BASEMENT MEMBRANE (Basal Lamina)
The basement membrane is a thin sheet of
extracellular fibers that underlies the
epithelium.
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EM STRUCTURE OF BASEMENT
MEMBRANE
Single central layer,lamina densa (60-300nm thick). It has
densely arranged typeIV collagen fibers.
On either side, laminalucida (10-50nm thick).It contains looselypacked type IV collagenfibers+ GAGs+proteoglycans.
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FUNCTIONS OF BASEMENT
MEMBRANE
1. It binds the epithelium to its connective tissueunderneath.
2. To provide a flexible support to epithelial cells.
3. acts as a mechanical barrier, preventingmalignant cells from invading the deepertissues.
4. It is also essential for angiogenesis.
5. It serves as a molecular sieve or ultrafilter e.g.this property is especially served by theglomerular capillaries.