Male sperm viability can be identified by dye rejection. Sperm viability is the proportion of live sperm in a drop of semen. Due to the lack of a power arm in the tail of some spermatozoa, they are immobile under microscopic observation, and the immobile spermatozoa observed in this case are not dead spermatozoa. Sperm viability can be evaluated by examining the integrity of the sperm membrane, and it is also possible to recognize whether the immobile spermatozoa observed under the microscope are live or dead. Dye can pass through the damaged cell membrane of the spermatozoa and stain the head of the spermatozoa a specific color. Therefore, the “dye rejection method” can be used to identify the integrity of the cell membrane to determine whether the spermatozoa are viable or not. Commonly used staining methods include eosin Y, eosin aniline black, and tepan blue.