📌 Definition of Cell Inclusions
· Cell inclusions are accumulations of materials within the cell that are not metabolically active.
· Usually present temporarily in the cytosol.
🟠 1. Stored Food Elements
Reserves of energy and building blocks within the cell.
a. Carbohydrates
· Stored as Glycogen.
· Primary Locations: Liver cells & muscle cells.
· Ultrastructure (Electron Microscope):
- Alpha Glycogen Granules: Clustered rosette shape.
- Beta Glycogen Granules: Single, separate granules.
· Staining Techniques (Exam Point): - Best’s Carmine: Glycogen → red color.
- PAS (Periodic Acid-Schiff): Glycogen → magenta color.
b. Fat (Lipids)
· Stored in fat cells (adipocytes) of adipose connective tissue.
· Staining Techniques (Exam Point):
- Sudan III / Sudan 3: Fat → orange color.
- Sudan Black: Fat → black color.
· H&E stain: Does not specifically highlight fat inclusions.
🟣 2. Pigments
Colored substances found in certain cell types; classified by origin.
a. Exogenous Pigments
· Originate outside the body, enter the cells.
· Examples (Exam Point):
- Carotene Pigments: From foods like carrots, tomatoes.
- Dust Pigments: Inhaled, found in respiratory system cells.
- Minerals: e.g. silver, lead entering through skin.
- Tattoo Marks: Classic exogenous pigment example.
b. Endogenous Pigments
· Produced by the body’s own cells.
· Examples (Exam Point):
- Hemoglobin Pigments: In RBCs; carry O₂ and CO₂.
- Hemosiderin: Iron-storage complex, seen in macrophage phagocytic cells.
- Melanin: Main pigment for skin, hair, eye color; made by melanocytes.
- Lipofuscin (Lipochrome): “Wear-and-tear” pigment; accumulates in long-lived cells (nerve & heart muscle cells).
🖇 3. Crystals
· Another form of cell inclusion.
· Example: Calcium carbonate crystals found within some cells.