We recently received an excellent question: How do you assess sperm vitality with Sperm VitalStain in viscous sperm samples?
First, we recommend diluting the sample using PureSperm Buffer when preparing a smear from raw ejaculate. This makes the procedure easier and helps achieve a more evenly colored smear. If vitality is assessed in a prepared sperm sample, viscosity should not be a problem. However, even when preparing smears from prepared samples, variations in staining intensity across the slide may still occur.
It is therefore important to select areas with an adequate level of background staining, but not excessive, as overly intense coloration can make it difficult to distinguish dead sperm cells.
Here are some pictures with different shades of background color that show the importance of choosing where to count the sperm to be able to identify colored sperm as easily as possible.