Staining

Definition

Staining is a technique used to enhance contrast in microscopic specimens by applying dyes that bind to specific cellular components. This process helps in identifying and differentiating various microorganisms under a microscope.

5 Must Know Facts For Your Next Test

1. Gram staining differentiates bacteria into Gram-positive and Gram-negative based on cell wall composition.
2. Simple stains use a single dye, while differential stains use multiple dyes to differentiate structures.
3. The acid-fast stain is crucial for identifying Mycobacterium species, including the tuberculosis-causing bacterium.
4. Negative staining highlights the capsules of microorganisms by staining the background instead of the cells.
5. Heat-fixing is often required before staining to kill and adhere microorganisms to the slide.

Review Questions

• What is the primary purpose of using stains in microscopy?
• How does Gram staining differentiate between types of bacteria?
• Why is heat-fixing an essential step before applying certain stains?

Related terms

Gram Staining: A differential stain that classifies bacteria into Gram-positive or Gram-negative based on cell wall structure.

Acid-Fast Stain: A staining technique used to identify acid-fast organisms like Mycobacterium.

Negative Staining: A method where the background is stained, leaving the specimen unstained for better visualization.