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Connective Tissue Histology
By
Dr. Mudassar Ali Roomi (MBBS, M. Phil)
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Connective Tissue or
supporting tissue
It is one ofthe basic tissues in our body.
Consist
s oftw
o basic element
s: Cells (relatively fewer)
Extra-cellular matrix or intercellular
substance (more abundant)
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Epithelium Vs connec
tive
tissue
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True Connective Tissue Cells
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True Connective Tissue Cells
Fibroblasts: Secrete both fibers and ground substance ofthe
matrix (wandering cells)
Macrophages: Phagocytes that develop from Monocytes
(wandering or fixed)
Plasma Cells: Antibody secreting cells that develop from BLymphocytes (wandering)
Mast Cells: Produce histamine that help dilate small blood
vessels in reaction to injury (wandering)
Adipocytes: Fat cells that store triglycerides, support, protect andinsulate (fixed)
Only loose areolar connective tissue contains all ofthe
aforementioned cells.
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Fibroblasts:
Are active cells that synthesize all collagen,
reticular, and elastic connective tissue fibers Synthesize glycosaminoglycans (GAGs),
proteoglycans, and glycoproteins of ground
substance.
Fibrocytes:
Smallerthan fibroblasts
Inactive or resting connective tissue cells
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Macrophages
Most numerous in loose connective tissue
Ingest bacteria, dead cells, cell debris, and foreign matter Are antigen-presenting cells (APCs) to lymphocytes for
immunologic response
Derived from circulating blood monocytes
Called Kupfer cells in liver, osteoclasts in bone, histiocytesin the skin, and microglia in central nervous system
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Lymphocytes
Most numerous in loose connective tissue of respiratory and
gastrointestinal tracts
Produce antibodies and kill virus-infected cells
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Plasma Cells
Characterized by chromatin distributed in radial
pattern in the nucleus (cart-wheel appearance)
Derived from lymphocytes exposed to antigens
Produce antibodies to destroy specific antigens
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Mast Cells
Closely associated with blood vessel
Found in skin, respiratory, and digestive systemconnective tissue
Spherical cells with fine, regular basophilic
granules
Release histamine when exposed to allergens,causing allergic reactions
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Extracellular ma
trix
Also called as intercellular substance
Extracellular matrix = fibers + ground
substance
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Matrix Fibers
Collagen Fibers: Large fibers made ofthe protein
collagen and are typically the most abundant
fibers. Promote tissue flexibility.
Elastic Fibers: Intermediate fibers made ofthe
protein elastin. Branching fibers that allow for
stretch and recoil
Reticular Fibers: Small delicate, branched fibers thathave same chemical composition of collagen. Forms
structural framework for organs such as spleen and
lymph nodes.
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Collagen Fibers
Type I: found in skin, tendons, ligaments,
fibrocartilage, and bone
Type II: found in hyaline and elastic cartilage
Type III: forms meshwork in liver, lymph node,
spleen, and hemopoietic organs
Type IV: found in basal lamina of basementmembrane
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Matrix Ground Substance
Hyaluronic Acid: heteropolysaccharides
(GAGs) found in true or proper connective
tissue.
Chondroitin sulfate: Jellylike ground
substance of cartilage, bone, skin an blood
vessels.
Other ground Substances:
Dermatin sulfate, keratin sulfate, and adhesion
proteins