Examining a Blood Smear

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Name/Date Examining a Blood Smear MATERIALS - sterilized lancets or needles - 20 clean microscope slides and coverslips - Canada balsam or other medium for permanent preparations - 95% ethyl or methyl alcohol - distilled water - Giemsa stain - low containers or Petri dishes - microscope which magnifies 200 times at least METHODS 1. Taking the blood: Cleanse a finger. With a sterile lancet, make a puncture on a fingertip. In the meantime, keep all the materials needed ready and protected from dust, particularly the clean microscope slides. 2. Making the smear: Place a small drop of blood near an end of a slide. Bring the edge of another slide in contact with the drop and allow the drop to bank evenly behind the spreader. The angle between the two slides has to be 30-40 degrees. Now, push to the left in a smooth, quick motion. The smear should cover about half the slide. With a single drop of blood, you can make several smears. In fact, to make a smear, it is enough to leave a spot of blood of 3 mm about in diameter on the slide. It is useful to perform many smears. In fact, not always they are successful, and with some attempts, it is easier to get one well prepared. To avoid producing clots, you must make each smear with fresh blood and straight after having deposited it. With the microscope, you should observe the smears to check that some of them are properly made. The red cells must not overlap each other, nor be so scarce as to be too spread out. 3.
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