2. Refer to the hemocytometer drawing in Figure 1. The cell numbers refer to the

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2. Refer to the hemocytometer drawing in Figure 1. The cell numbers refer to the total cell count in each of the numbered large squares. If the sample is undiluted and unstained, what is the cell density of the sample? (Show how you figured out your answer, and include units) Square #1:125 #2:135 #3:130 #4:135 1 mm 3 mm 4 1 m Figure 1 3. Using the same cell counts for squares 1-4 as in Question #2, calculate the cell density for 1ul of blood which was diluted in 99 saline solution, then mixed with 100 methylene blue stain before counting. (Show how you figured out your answer, and include units)

Explanation / Answer

Annswer 2.

Each square of hemocytomemter has a defined volume. The 1mm square have a volume of 100nl (0.1ul), means each square will have 0.1ul of cell suspention subjected for counting. According to the principle, cells in each 1mm square is counted and then divided by four to get the average number of cells per 1mm square means average number of cells per 0.1ul (unit volume). In this question, the counted number of cells in each 1mm square is given, so the average would be 125+135+130+135=525 cells divided by 4, (525/4 =131.25). Each 1mm square have 131.25 (or 131 after round off) cells per 0.1 ul. Now to get the number of cells per microliter multiply this by 10 meaning 131.25x10= 1312.5 cells per ul of sample subjected for counting without dilution and without staining.

Answer 3

Now we know that each ul of this blood (subjected to hemocytometer) have 1312.5 cells/ul. since this was diluted 100 times (1 in 99) with saline solution, so to get the cell density in this sample we need to muliply it with 100 meaning 1312.5x100= 131250 or 1.3125x105 cells/ul. Next it was further diluted with 100 ul methylene blue meaning 2 times dilution (100ul of blood and saline+100ul methylene blue) so to get the cell density we need to again multiply this with 2 then it will be 1.3125x105 x2=2.625x105 cells/ul. To express the cell number in per ml unit volume, multiply it with a factor of 1000, meaning 2.625x105 x103 = 2.625x108 cells/ml.

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2. Refer to the hemocytometer drawing in Figure 1. The cell numbers refer to the

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