Blood Cell Counts
A common physiological assessment of blood is the determination of the number of blood cells present.
In this lab, you will perform two types of cell counts: 1) Hematocrit (a measurement of the number of red blood cells currently in the blood); and 2) Differential white blood cell count (a determination of the percentage of each type of white blood cell in the blood). Your data for this portion of the lab along with the blood typing data will be recorded on the Blood Lab Worksheet. Please print out a copy of the worksheet to be turned in with your results.
General Protocol
You will be assigned a number between 1 and 24. This number will determine the set of slides you use for your cell counts.Record this number on your Blood Lab Worksheet. Use the same number for both the red and white blood cell counts. At the end of these instructions there is a link to the Cell count home. Once you have accessed the Cell count home use the pull-down menu under your assigned number to select either the red (Hematocrit) or white (Differential white blood cell) blood cell count option.
Hematocrit Protocol
Red blood cell counts employ a special microscope slide called a hemocytometer. A hemocytometer is a special glass slide with a small chamber, or counting area, for counting cells in a given volume. The counting area has a grid on it to allow for easier counting of the cells. This technique allows for an estimation of the total number of red blood cells present in a sample. The large numbers of red blood cells present in blood (discussed above) make it impossible to count every cell. Instead, you will use a simulated hemocytometer to estimate the number of RBCs present.
After you select your “Red blood cell count”, you will be presented with 4 images, or “slides”, of blood cells. Each image has a grid superimposed on it, much like the grid found on a hemocytometer slide. The grid divides the area to be counted into 16 smaller sections, allowing you to count the red blood cells in smaller, manageable groups. Count all of the red blood cells in each of the grid squares. DO NOT count a cell if ANY part of the cell touches ANY part of the OUTER grid lines. If a cell touches or overlaps any of the INNER grid lines, count the cell but be sure to count it only once. There may be white blood cells present in these samples. The white blood cells are not to be counted. Count only the red blood cells. Repeat this procedure for each of the four images.
Count and record the number of red blood cells in each square and, ultimately, the entire area of the grid. Record each of your cell counts in the table on the Blood Lab Worksheet. Add up your counts from all 4 slides and record the total on the “Total” line of the worksheet. Once you have added all of your counts, multiply your total by 2500 (Note: DO NOT use 10,000 as indicated in the lab manual). Record this value, your RBC estimate, in the appropriate blank and answer the two questions on the worksheet.
Differential White Blood Cell Count Protocol
Select the appropriate White blood cell count section. You will be presented with a series of blood smear slides. For each slide, you will identify and record the number of each of the 5 different types of leukocytes present. Record your white cell count data on Blood Lab Worksheet.
For each slide, identify the WBCs present and place a tick mark next to the name of the white blood cell you see. When you have counted 100 TOTAL white blood cells (all WBCs together, NOT 100 of each type of WBC) STOP! Count the number of ticks for each cell type and determine the percentage of each type of leukocyte present in your sample. Record the percentages in the table on your worksheet and answer the question.