Chapter 8: Connective Tissue Flashcards
Masson’s Trichrome Purpose
To differentiate between Collagen and smooth muscle
esp for tumors and identifying increases in collagenous tissue for diseases such as cirrhosis of the liver
Masson’s Trichrome Principle
Uses 3 dyes:
Biebrich Scarlet: acid dye that stains all acidophilic tissue red (cytoplasm, muscle, and collagen)
Phosphotungstic Acid PTA or Phosphomolybdic Acid PMA: This acid causes the scarlet to diffuse out of collagen, which is more permeable than cytoplasm, which remains red in addition to muscle fibers
Aniline Blue: stains collagen blue by binding to the PTA/tissue complex (PTA is like the primary and blue is like the secondary)
Masson’s Trichrome Preferred Fixative
Bouin’s is preferred, 10% NBF may be used
Masson’s Trichrome Basic Procedure
- Deparaffinize and hydrate
- Rinse in water
- Mordant in Bouin’s
- Wash in running water to remove yellow from Bouin’s
- Rinse in water
- Stain in Weigert Iron Hematoxylin
- Wash in running water
- Rinse in water
- Stain in Biebrich Scarlet Acid-Fuchsin
- Rinse in water
- PTA/PMA to differentiate collagen from cytoplasm and muscle
- Stain in aniline blue
- Rinse in water
- Differentiate collagen in 1% acetic acid
- Dehydrate, clear, coverslip
Masson’s Trichrome Results
Nuclei: black
Cytoplasm, keratin, muscle fibers: red
collagen and mucin: blue
Masson’s Trichrome Technical Notes
Light green is an alternative counterstain to aniline blue, especially when collagen is predominant
pale blue collagen staining is a sign of overdifferentiation with acetic acid
Picric acid is explosive when less than 10% aqueous, make sure it (the Bouin’s) doesn’t spill and evaporate in the oven during heating step
Gomori 1-Step Trichrome Purpose
Differentiation between collagen and smooth muscle fibers
Also for identifying an increase in collagenous connective tissue fibers
Gomori Trichrome Principle
Uses one stain made of three components to reduce the number of steps
Chromotope 2R stains plasma red
Fast green FCF, light green, or aniline blue stains collagen
These two stains are combined with PTA and acetic acid, which causes muscle and cytoplasm to stain red
The tungstate ion binds to collagen, and that metal/tissue complex binds the aniline blue collagen stain, which is then differentiated by acetic acid
Gomori Trichrome Preferred Fixative
Any except Bouin’s (which is used as a mordant to intensify the stain colors)
Gomori Trichrome Basic Procedure
- Deparaffinize, hydrate
- Rinse in water
- Mordant in Bouin’s
- Wash in running water
- Stain in Gomori Trichrome stain
- Differentiate in 0.5% Acetic Acid
- Dehydrate, clear, coverslip
Gomori Trichrome Results
Nuclei: black
Cytoplasm, keratin, muscle fibers: red
Collagen and mucin; blue or green depending on the counterstain
Gomori Trichrome Technical Notes
Color intensity can be varied by changing the pH
pH 1.3 gives the best binding, but acetic acid is pH2.5
1.3 can be obtained by using HCl
Zinc-formalin is a good fixative for trichrome stain that doesn’t require mordanting with Bouin’s
Van Gieson (Picric Acid-Acid Fuchsin) Purpose
Usually used as a counterstain rather than a primary stain, especially for elastic techniques such as Verhoeff-van Gieson VVG or elastic-van Gieson EVG
Van Gieson (Picric Acid-Acid Fuchsin) Principle
In a strong acidic solution, collagen is selectively stained by acid-fuchsin, which is an acid aniline dye
HCl differentiates between collagen and muscle fibers
Picric acid provides acidic pH and stains the muscle and cytoplasm
Van Gieson (Picric Acid-Acid Fuchsin) Preferred Fixative
Any
Van Gieson (Picric Acid-Acid Fuchsin) Basic Procedure
- Deparaffinize, hydrate
- Stain in Weigert Iron Hematoxylin
- Wash in running water
- Stain in Van Gieson (acid fuchsin+picric acid)
- 95% alcohol
- Dehydrate, clear, coverslip
Van Gieson (Picric Acid-Acid Fuchsin) Results
Nuclei: black
Collagen: Brilliant red
Muscle and Cytoplasm: yellow
Van Gieson (Picric Acid-Acid Fuchsin) Technical Notes
Weigert Iron hematoxylin resists acidic solutions
pH of picric acid is very important, if the solution is not saturated the collagen cytoplasm and muscle fibers may all stain pale pink to pale orange
HCl can help to sharpen color differentiation
What are the 3 types of connective tissue fibers?
Elastic, Collagen, Reticular
Elastic
Most abundant in tissue requiring flexibility, because they allow tissue to stretch
Present in most fibrous connective tissue
not seen on HandE
Collagen
Provide strength to connective tissue proper
Very eosinophilic
Seen under light microscopy
Birefringent under polarized light
Cross-striated in EM
Demonstrated with Masson’s or Gomori Trichrome stains
Reticular
Type of Collagen
Not seen in HandE
Absorb silver from solutions
Smaller than most collagen fibers
What are the three types of muscle tissue?
Skeletal, smooth, and cardiac
Skeletal muscle type 1 (slow twitch)
.
Skeletal muscle type 2 (fast twitch)
.
Smooth Muscle
No striations, no branching, looks a lot like connective tissue on H and E, central mono-nucleated, involuntary, different ratio of actin and myosin than skeletal
Skeletal Muscle
Striations, no branching, Z-lines, peripheral multinucleated, voluntary
Actin and myosin are the major contractile proteins
Cardiac Muscle
Striations, branching, intercalated disks, mono-nucleated, involuntary
What are the 7 types of connective tissue cells?
Fibroblasts Mesenchymal Cells Adipose Mast Cells Macrophages Plasma Cells Blood Cells
Fibroblasts
Main cell type and most common in loose CT
Almost the only cell type in regular CT
Flattened nuclei, spindle shaped cells
Mesenchymal Cells
Primitive, relatively undifferentiated
Look very similar to fibroblasts
Differentiate when needed
Adipose
Fat cells which synthesize and store lipids
Common in loose connective tissue
Flattened nucleus
Must be cut frozen at -30C because paraffin processing does not preserve lipids
Mast Cells
Trigger immune and inflammatory responses
Abundant secretory granules
Contain Histamine and Heparin
Exhibit metachromasia when stained with Toluidine Blue
Resemble basophilic leukocytes found in the blood
Macrophages
“Big eaters”
Scavenger cells that process antigenic material and present it to the lymphocytes
Blood leukocytes are their precursors
Plasma Cells
Derived from B lymphocytes
Produce immunoglobulins
Deeply basophilic cytoplasm
Blood Cells
Many types
Red blood cells are the most common
What is the basement membrane?
Also called the basal lamina
Between the epithelium and underlying connective tissue
Demonstrated by carbohydrate methods because they contain more sugar than ordinary collagen
What is the function of the basement membrane?
Beneath the epithelium and connects it to the underlying connective tissue
Provides physical support to the epithelium, cell attachment, and ultrafiltration
What is a unique feature of mast cells that helps in demonstration?
Exhibit metachromasia when stained with Toluidine Blue
Which procedures are used to demonstrate lipids?
Oil Red O, Sudan Black, Toluidine Blue
Describe Silver Oxidation
Oxidizes reticulin to aldehyde groups