36 Questions
What is a characteristic of a good decalcifying agent?
Stable
What is a factor that affects the rate of decalcification?
Concentration of the agent
Which of the following is NOT a type of decalcifying agent?
Electrolysis
What is an advantage of a good decalcifying agent?
It is easily available
What is a unique characteristic of a decalcifying agent?
It is inexpensive
What is a consideration when choosing a decalcifying agent?
Its cost
What is the purpose of decalcification in tissue samples?
To facilitate normal cutting of tissue in sectioning and prevent obscuring microanatomical detail
Which of the following organs require decalcification?
Bones and tuberculous lungs
What is the most common decalcifying agent used in tissue samples?
Nitric acid
What effect does nitric acid have on the tissue sample?
It imparts a yellow coloration to the tissue
What is the percentage of nitric acid used in decalcification?
5-10%
Why is decalcification necessary for arteriosclerotic vessels?
To remove calcium and lipids
What is a key characteristic of a good decalcifying agent?
Rapid, cheap, and inexpensive
Which of the following is NOT a variation of decalcifying agents?
Chloroform
What is the purpose of ROH in decalcifying agents?
To act as a tissue softener
What is the common brand of decalcifying agents that contains Na2EDTA?
Cal-Ex
What is the primary function of chelating agents in decalcification?
To form complexes with calcium salts for ease of removal
What is the characteristic of Phloroglucinol-Nitric Acid?
It is the fastest decalcifying agent
Which of the following decalcifying agents is best suited for small bone fragments?
Chromic Acid (Flemming's Fluid)
What is the main advantage of using a simple decalcifying agent?
It has only one ingredient
What is the pH range at which Citric Acid Citrate Buffered Solution works best?
4.0-4.5
What is the duration of the decalcification process using Electrophoresis for small tissue samples?
1-3 weeks
Which of the following is a characteristic of a good decalcifying agent?
It is safe to use
What is the purpose of adding urea or Sodium Thiosulfate/sulfate to decalcifying agents?
To improve the effectiveness of the agent
What is the advantage of using Citric Acid Citrate Buffered Solution in decalcification?
It shortens the time needed to remove calcium ions or calcium salts
What is the method used to measure the decalcification extent?
All of the above
What is the primary application of Electrophoresis in decalcification?
Immunohistochemistry and enzyme staining
What is the pH range at which Electrophoresis works best?
7.0-7.4
What is the main purpose of using von Ebner's fluid in tissue decalcification?
To decalcify teeth and small bones
Why is formic acid not recommended for use with hydrochloric acid and nitric acid?
It is not effective in removing calcium ions from decalcifying solutions
What is the advantage of using formic acid in decalcification?
It is good for routine decalcification of post-mortem research tissues
What is the principle of using von Ebner's fluid in decalcification?
To increase solubility
What is the effect of using nitric acid in decalcification?
It is slower and causes more distortion compared to hydrochloric acid
How can the extent of decalcification be measured?
By using physical methods such as bending or poking the tissue sample
What is the composition of von Ebner's fluid?
Hydrochloric acid, 36% NaCl, and distilled water
What is the effect of using formic acid that contains a large amount of nitric acid in decalcification?
It produces better nuclear staining and less tissue distortion
Study Notes
Decalcification
- Decalcification facilitates normal cutting of tissue in sectioning and prevents obscuring microanatomical detail of tissue.
- Organs that require decalcification: bones, tuberculous lungs, arteriosclerotic vessels, and teeth.
Characteristics of a Good Decalcifying Agent
- Stable
- Easily available
- Inexpensive
- Easy to prepare
Factors Affecting Rate of Decalcification
- Concentration
- Nitric acid: 5-10%, fastest decalcifying agent, imparts yellow coloration to the tissue sample.
Types of Decalcifying Agents
- Acid: nitric acid, hydrochloric acid, formic acid, trichloroacetic acid, chromic acid, sulfurous acid, and citric acid citrate buffered solution.
- Chelating Agents: remove calcium ions from the tissue, used in immunohistochemistry and enzyme staining.
- Ion Exchange Resin: increases solubility, removes calcium ions, and is not recommended for hydrochloric acid and nitric acid fluids.
- Electrophoresis: attracts calcium ions to the cathode part of the agarose gel, shortens time, and utilizes 88% formic acid.
Nitric Acid
- 5-10% concentration
- Fastest decalcifying agent
- Imparts yellow coloration to the tissue sample
- Remedy: add urea or sodium thiosulfate/sulfate to remove nitrous acid
- Variations: 10% aqueous nitric acid solution, formol-nitric acid, perenyi's fluid, and phloroglucinol-nitric acid.
Hydrochloric Acid
- 1% concentration
- Provides good nuclear staining
- Slower and causes more distortion compared to nitric acid
- Variations: von ebner's fluid and hydrochloric acid with 36% NaCl + distilled water.
Formic Acid
- Good for routine decalcification of post-mortem research tissues, small pieces of bone and teeth, and ISH staining.
- If the formic acid contains a large amount of nitric acid, it produces better nuclear staining and less tissue distortion.
- Variations: formic acid and formic acid-sodium citrate solution.
Other Decalcifying Agents
- Trichloroacetic acid: best for small bone spicules, good nuclear staining, and slow.
- Chromic acid (flemming's fluid): best for minute bone spicules.
- Sulfurous acid: best for minute pieces of bone and weak.
- Citric acid citrate buffered solution: pH 4.5, used for minute bone spicules.
Learn about the importance of decalcification in histology, characteristics of a good decalcifying agent, and factors affecting the rate of decalcification.
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