Attention toward staining blood smears for examination under a light microscope .
It is not always easy to achieve a homogeneous staining when preparing several smears. This can be due to some variables, such as:
– the age of the staining mixture;
– the staining time may be slightly different between the various staining series;
– the pH of the water of the solution of the stain may influence the final staining.
In clinical laboratories, the staining is currently done mechanically and is much more controlled.
Due to all these factors, the staining of cells in smears may be darker in some preparations and less dark in others. Some cells may stain more strongly with certain dyes in some smears than in others.
Red blood cells, for example, should stain pink or light orange, but sometimes they take on a grayish or bluish tone. When examining a blood smear under the microscope, observe carefully the color of the red blood cells before drawing conclusions about the staining of white blood cells.
The series of figures shown in the following pages of this chapter includes images at different magnifications. To get a correct idea about the size of a particular cell, it is very helpful to compare its diameter with the diameter of a red blood cell.