L.9 Microbes & Accumulations Flashcards
What is cellular pathology?
The study of the accumulation of substances within tissues due to abnormalities in metabolism, transport, or clearance of normal body constituents.
What can the accumulation of substances in tissues lead to?
Visible changes in tissues and contribute to disease processes.
List the types of accumulated substances in cellular pathology.
- Fats
- Proteins
- Carbohydrates
What may cause the accumulation of substances?
- Defective cellular packaging or transport
- Abnormal metabolism
- Reduced degradation or removal
Can accumulations of substances in tissues be reversible?
Yes, but persistent accumulation may lead to cell injury.
How are lipids processed in histopathology?
Differently due to their physical properties; adipose tissue dissolves easily during routine histological preparation.
Why is thermal fixation essential for lipids?
To preserve lipids during histological preparation.
What is cryotomy?
A technique that involves cutting frozen sections of tissue to preserve lipid content.
What are the steps involved in cryotomy?
- Receiving tissue fresh (without fixation)
- Snap freezing in liquid nitrogen
- Sectioning at -20°C using a cryostat
- Fixing sections briefly in formalin vapour
- Transferring to isopropanol to maintain lipid solubility for staining
What is Oil Red O?
A red hydrophobic dye used to stain neutral triglycerides and lipids.
It works on the principle of solubility, where the dye dissolves in the lipid component rather than binding chemically.
How is Oil Red O typically prepared?
In isopropanol.
It selectively stains lipid droplets a vivid red.
What type of stain does Sudan Black B produce?
A blue-black stain.
It interacts with the acidic groups in lipid molecules.
What is a primary use of Sudan Black B?
To detect phospholipids and neutral fats.
It is less commonly used than Oil Red O.
What does amyloid refer to?
An abnormal, insoluble protein aggregate.
It is typically produced in the bone marrow and deposited extracellularly under pathological conditions.
How does amyloid appear under the microscope?
Waxy and translucent.
It is found in diseases such as amyloidosis, and not present in healthy tissue.
What is the effect of amyloid deposits on tissue?
They disrupt tissue structure and function.
This leads to clinical symptoms depending on the organs involved, such as kidneys, heart, or liver.
What is the gold standard stain for detecting amyloid deposits?
Congo Red Stain.
Amyloid binds Congo Red dye and exhibits distinctive apple-green birefringence under crossed polarized light.
What does the apple-green birefringence indicate?
The presence of amyloid histologically.
This property is crucial for confirming amyloid deposits.
What do histological findings provide clues to?
Underlying infections
Especially when microbiological culture is not feasible.
Why investigate infectious agents in histology?
Common targets and incidental findings
Microorganisms are frequently investigated with special histochemical stains and can be revealed incidentally.
What types of samples can microorganisms be seen in?
Histology and cytology samples
What is a challenge in identifying infectious agents?
Infectious agents may not be easily visible with routine H&E staining
What are the common types of infectious agents investigated?
- Bacteria
- Fungi
- Viruses
- Parasites and Protozoa
More precise identification often uses immunohistochemistry (IHC) and molecular techniques.
