1. What is a differential stai
1. What is a differential stain?
2. Give three reasons for using heat as a fixative in Gramstaining.
3. What is the use of the stage and ocular micrometer inmicrometry.
Answer:
Ans 1: Differential Staining is a staining process which usesmore than one chemical stain. Using multiple stains can betterdifferentiate between different microorganisms orstructures/cellular components of a single organism. Differentialstaining is used to detect abnormalities in the proportion ofdifferent white blood cells in the blood. The process or resultsare called a WBC differential. This test is useful because manydiseases alter the proportion of certain white blood cells.
2: Reasons for using heat as a fixative in Gram Stainingare:
a) Heat fixing denatures bacterial enzymes, preventing them fromdigesting cell parts, which causes the cell to break, a processcalled autolysis.
b) Heat fixing kills the bacteria in the smear, firmly adheresthe smear to the slide.
c) Heat fixing allows the sample to more readily take upstains.
3: An ocular micrometer is a glass disk that fits in amicroscope eyepiece that has a ruled scale, which is used tomeasure the size of magnified objects. The physical length of themarks on the scale depends on the degree of magnification.
A Stage micrometers are used on the stage of the microscope andprovide a simple and reliable means of accurately calibratingeyepiece graticules.