Microscope Applications
Microanatomy/Histotechnology
Quality control slides performed with each staining procedure must be microscopically assessed daily. The objectives most commonly used include scanning lens 4x, low power 10x, high-power dry lens 40x (oil immersion lens 100x may be used by pathologist). Slides are usually cover slipped. Both magnification (increased size) and resolution (increased ability to see fine detail) are required for staining assessment.
Hematology
A good light microscope is essential for a microscopic evaluation of a peripheral blood smear. Low power 10x, allows for a general review of the color and distribution of blood cells, 40x to locate a good counting area, Oil-50x to perform WBC differentials, Oil-100x perform RBC morphology/platelet evaluation.
Microbiology
The Gram stain is performed on a thin smear of bacteria that has been air-dried and heat fixed. The staining procedure consists of applying stains to bacteria and reactions based on chemical differences in the structure of the cell wall. Staining reveals the shape, structure of bacteria present. Gram-positive bacteria will stain purple (round) and gram-negative bacteria stain red (rod shaped). The stained area is assessed on low power 10x, then a drop of oil added and observed with the Oil-100x.
Urine Microscopics
Performed, when required, as part of a urinalysis. Urine sediment is observed initially on low power 10x, then under high power 40x (high dry). Common elements found in urine sediments are WBC, RBC, epithelial cells, mucous, bacteria, yeast, casts and crystals. These preparations are unstained and may be difficult to ‘see’, however, adjusting the light adjustment knob (rheostat) and/or dropping the condenser to obtain contrast between the object and the background is usually required. Note: When this adjustment is made Kohler illumination has been lost!
Fluid Analysis
Body fluids received in the lab such as cerebrospinal fluid (CSF), peritoneal, pleural, and joint are examined for the presence of WBC, RBC, bacteria and crystals. They are examined under low power 10x, then under high power 40x (high-dry).