Connective Tissue
ANSC 590
Animal Growth and Development
Karey L. McPhee
Sept. 2, 2008
Textbook Definition

A primary tissue type involved in providing
structural support for tissues and organs.

Framework in all organisms in which other
systems are placed
Connective Tissue:

Varies greatly in its physical and functional
characteristics

Has a rich, extensive extracellular matrix that
contains relatively few active cells
Connective Tissue Proper


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Extracellular substance
Ranges from semi-solid, glue-like substance
to a rigid, amorphous material
Includes:
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Ground Substance: viscous solution imbedded
with proteinaceous fibers
Fixed cells and Wandering cells
Example: Blood vs. Bone and Cartilage
Cell Types

Macrophages

Small cells capable of movement (ameboid)

Consume damaged cells and foreign substances

Abundant at sites of injury
Cell Types

Mast Cells

Move freely w/in connective tissues
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Wandering cells
Primarily responsible for release of histamines

Convey inflammation response
Cell Types

Fibroblasts
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Fixed cells

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“anchored” into connective tissue
Produce fibrous structures that reinforce
amorphous structure
Ground Substance

Fluid-like structure of connective tissue
proper

Consists of soluble proteoglycans

Most prominent proteoglycans:

Chondroitin Sulfates and Hyaluronic Acid


C.S. is abundant in tendons and cartilage
H.A. is very viscous and found in joints
 Crucial part of synovial fluid (lubrication)
Primary Reinforcement
Proteins

Collagenous Fibers

Reticular Fibers

Elastic Fibers
Collagen Fibers

Collagen: most abundant protein found in animals

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20-30% of protein in the body
Primary sequence (polypeptide) is called Alpha Chain
Relatively inelastic
Coils into left-handed helix, but entire molecule is not
helical
 Helical portions provide stability for the molecule
 Non-helical portions help align molecule with other Alpha
Chains
Secreted from precursor molecule (from fibroblast):
Procollagen
Collagen Fibers cont.

Ultimate structure: Pentafibrils

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Arranged in staggard formation
Yields highly organized fibers occurring outside
the cell
Pentafibril strength is relatively low
Tensile strength comes from cross-linkages
between collagen molecules
Many types of collagen fibers (11 listed in
text)
Reticular Fibers

Formation is similar to collagen fibers, except
they do not form large bundles of fibers

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Very small and delicate
Combined with abundant ground substance
and randomly arranged

creates loose type of connective tissue

Parenchyma: surrounds many organs
Elastin

Differs greatly from collagen in functional properties

Contains two unique amino acids

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Desmosine
Isodesmosine

Capable of being stretched to nearly 2x their length

Secreted from precursor molecule: tropoelastin

Abundant in compliant tissues
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Blood vessels
Ligaments
Lungs
Skin