Questions and Answers
Alcian blue is an effective dye for demonstrating neutral mucins.
False
The dye-tissue complex formed by Alcian blue is soluble after staining.
False
Phenylhydrazine is used to differentiate between neutral mucins and acid mucins.
True
Sialomucins that contain O-acetyl groups are resistant to enzymatic breakdown.
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Connecting tissue mucins can exhibit positive results if oxidation is maintained for up to 48 hours.
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Alcian blue has low specificity for acid mucins and calcium salts.
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Heparin is found in the dermis of the skin.
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The staining intensity of a tissue component with Alcian blue increases when used at a lower pH.
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Keratan sulphate contains uronic acid.
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Alcian green 3BX stains tissues with a blue-green color.
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Heparan sulphate is found in connective tissue of the aorta.
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N-acetyl-D-glucosamine is a component of both heparin and heparan sulphate.
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The sulphate ester groups on heparin are primarily found at C2 of the glucosamine.
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Keratan sulphate is located in the cornea and intervertebral discs.
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Iduronic acid is present in both heparin and heparan sulphate.
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The presence of a sulpho-amino group differentiates heparin from heparan sulphate.
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MUC genes are located on five different chromosomes, with a majority clustered on chromosome 11.
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Chondroitin sulphate A is found in the dermis of the skin and contains D-galactosamine.
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Strongly sulphated mucins are usually PAS-positive under standard periodic oxidation.
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Mucins can be categorized into three groups: acidic, neutral, and basic.
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Fibroblasts, endothelial cells, and chondrocytes are all types of cells that produce strongly sulphated connective tissue mucins.
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Chondroitin sulphate C is sulphate-esterified at the C4 position on the galactosamine molecule.
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Weakly sulphated mucins play a significant role in the composition of connective tissue.
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Atypical sulphated mucins are recognized for their high reactivity at low pH values.
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Enzyme labile sialomucins are unaffected by sialidase enzyme.
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Enzyme resistant sialomucins are PAS-positive.
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Hyaluronic acid consists of N-acetyl-D-glucosamine and D-glucoronic acid.
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Sulphated sialomucins are commonly accepted as a distinct group.
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Enzyme labile sialomucins are found in bronchial submucus glands.
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Hyaluronic acid has no effect on the viscosity of synovial fluid.
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The masking O-acetyl group is found on the sialic acid molecule of enzyme resistant sialomucins.
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Sialidase digestion enhances the demonstration of weakly sulphated mucins.
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Hexamine silver technique was first introduced by Gomori in 1946.
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Alpha amylase is extracted from the liver of hogs.
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The hexamine-silver solution should be heated to 72°C before incubation.
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Beta amylase can digest both branched and straight-chained glycogen.
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Diastase contains both alpha and beta amylase.
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Hexamine silver technique results in a red compound when glycogen is oxidized.
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Mucins will not be stained when using any oxidant in the hexamine silver technique.
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Pectinase is listed as an enzyme used in glycogen demonstration.
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Study Notes
MUC Genes and Chromosomes
- MUC genes are located on more than five different chromosomes, with a significant cluster on chromosome 11.
Types of Mucins
- Mucins are classified into two main categories: acidic mucins and neutral mucins.
Acidic Mucins
- Acidic mucins can be further divided into sulphated types and carboxylated types.
Strongly Sulphated Mucins
- Strongly sulphated mucins include types found in connective tissue and epithelial cells.
- They react at low pH and are usually PAS-negative under standard conditions.
- Key cell types producing strongly sulphated mucins include fibroblasts, endothelial cells, osteocytes, chondrocytes, and mast cells.
Sub-types of Strongly Sulphated Mucins
- Chondroitin Sulphate A: Present in cartilage; contains D-galactosamine and D-glucuronic acid.
- Chondroitin Sulphate B: Found in aorta, heart valves, and skin; contains 1-iduronic acid.
- Chondroitin Sulphate C: Similar to A but sulphated at the C6 position; found in cartilage, umbilical cord, and skin.
- Heparin/Heparan Sulphate: Contains N-acetyl-D-glucosamine and D-glucuronic acid; found in mast cells (heparin) and in aorta/cardiac tissue (heparan).
- Keratan Sulphate: Composed of sulphated N-acetyl-D-glucosamine and galactose; found in cornea and intervertebral discs.
Sialomucins
- Two types exist: enzyme labile and enzyme resistant.
- Enzyme Labile Sialomucins: Digestible by sialidase and found in various glands and goblet cells.
- Enzyme Resistant Sialomucins: Resistant to denaturation; consist of N-acetyl-O-acetyl neuraminic acids.
Sulphated Sialomucins
- Debate exists regarding their classification; similar reactions to weakly sulphated mucins.
Hyaluronic Acid
- Commonly occurs in fibroblasts; contains N-acetyl-D-glucosamine and D-glucuronic acid.
- Essential in synovial fluid, influencing its viscosity.
Hexamine Silver Technique
- Developed by Gomori and modified by Grocott; involves oxidizing glycogen to form aldehydes that react with silver nitrate.
- Important for visualizing mucins but requires careful attention to timing and conditions during the process.
Glycogen Demonstration Enzymes
- Various enzymes such as alpha amylase, beta amylase, and diastase are utilized for glycogen digestion.
- Alpha Amylase: Extracted from hog pancreas, capable of digesting both branched and straight chains.
- Beta Amylase: From barley or sweet potato, only digests straight chains.
- Diastase: Common and stable enzyme that contains both alpha and beta amylase.
Mucin Staining Techniques
- Phenylhydrazine-PAS: Differentiates between neutral and acid mucins through selective reactivity.
- Alcian Blue: Popular for demonstrating acid mucins; operates at pH 2.5 for high specificity and strong coloration.
Varying pH for Alcian Blue
- The intensity of staining increases at optimal pH levels where the reacting groups are fully ionized.
- Various forms of Alcian dyes (e.g., Alcian Green, Alcian Yellow) offer alternative staining options for different acid mucins.
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Description
Explore the fascinating world of MUC genes, which are spread across multiple chromosomes, primarily clustered on chromosome 11. This quiz also delves into the classification of mucins into acidic and neutral types, outlining their specific characteristics and functions.
