It is important to distinguish between vitality and motility, since total asthenozoospermia does not imply total necroozoospermia, so we must carry out this test especially when the mobility of progressive spermatozoa is below 40%.
Sperm vitality is the test that indicates the number of live sperm present in an ejaculate sample. It is important to distinguish between vitality and motility, since total asthenozoospermia does not imply total necroozoospermia, so we must carry out this test especially when the mobility of progressive spermatozoa is below 40%.
Mainly, there are two methodologies to study the vitality of sperm:
- Eosin staining
- is the most used test in most assisted reproduction units. This methodology consists of distinguishing live sperm from non-living sperm by the coloration they present after the sperm have passed through a series of fixation and coloration processes. The basis of this sperm vitality test is based on the absorption of different dyes, eosin in this case, by dead cells, in such a way that when counting we will observe non-stained sperm (alive) and stained sperm (dead) , expressing said result as a percentage after having counted at least 200 cells.
- Hypo-osmotic test
- technique based on the semi-permeability characteristic of the membranes and its variations in media of different osmolarity. By subjecting the spermatozoa to hypoosmotic solutions, those that are alive will swell because their membranes are acting to balance the concentrations. In contrast, dead sperm do not have this control, so they will not swell.
Once the sperm count has been carried out, we would consider the sample to have normal vitality as long as there is a percentage equal to or greater than 58% of live sperm.
