What is the most likely reason for cells on a hemocytometer ...

[Davideckstein7]

What is the most likely reason for cells on a hemocytometer appearing fuzzy when switching from low power to the 40 objective?
 
  a. Condenser not lowered enough
  b. Hemocytometer not cleaned properly
  c. Oil on the 40 lens
  d. Cells not allowed to settle

Question 2

Which of the following microscopic procedures requires high contrast and lower light?
 
  a. Examining unstained objects (e.g., urine sediments)
  b. Evaluating red cell morphology
  c. Manual differentials
  d. Platelet estimates

[joshraies]

Answer to Question 1

ANS: C
Oil should never be allowed to touch any lens that is not an oil immersion lens. If it mistakenly does get on the 40 lens, then the object will appear fuzzy and unclear. The condenser should be in the highest position for best visualization. If a hemocytometer is dirty, then it will make it difficult to distinguish cells from debris. If cells are not allowed to settle, then they will not all be in the same plane of focus and some may be missed for counting purposes.

Answer to Question 2

ANS: A
Urine sediments are generally unstained. To improve the contrast, and thus the ability to identify the elements, requires high contrast and lower light. All the other items use a Wright-stained blood film for evaluation. The stain allows for contrast between the various cell components; these are all performed using an oil immersion lens, thus requiring a large amount of light.

[Davideckstein7]

Excellent

[scottmt]

TYSM