Do watch the rest of my semen analysis videos by clicking on links below: Semen analysis Complete Video: Semen Analysis 1-6 Liquefaction time, Volume, Colour, pH, Odour, Viscosity: Semen analysis Sperm Motility Test: Semen analysis Sperm Viability Test: Semen Analysis Sperm Morphology: Semen analysis Sperm Count: Semen analysis Fructose content: Eosin and Nigrosin Stain Preparation (for Viability Test): #MedicalLab #ReproductiveBioLab #ThomasTKTungnung #CytologyLab #AnimalPhysioLab In the sperm motility test, if non motile sperms are found, one has to assess what fraction of these non motile sperms are still alive and what fraction are dead. Sperm viability test is therefore used to determine if non-motile sperms are alive or dead. This particular test is applicable in cases where the motility of the sperms are drastically low that is less than 20%. Viability testing is based on the principle of differential staining property of live and dead sperms also known as dye exclusion assays. Dye exclusion assays rely on the ability of live sperms to resist absorption of certain dyes, whereas these dyes penetrate and stain non-viable or dead sperms. A combination of Eosin and Nigrosin stains is commonly used in sperm viability testing. Make sure to watch my video on how to prepare eosin and nigrosin stain for sperm viability testing by clicking on the link given on the top right corner of the screen right now, or the link given in the video description below. Just as in the sperm motility test, sperm viability is also assessed within 60mins of collection of the sample. A drop of liquefied semen sample is taken on a glass slide. 5 drops of Eosin-Nigrosin stain (or 2drops 1% eosin + 3 drops 10% Nigrosin stain) is added to the sample. The stain and sample are gently mixed on the slide and allowed to stand for 10-20 seconds. Take a second slide, touch one edge of this slide on the sample and prepare a smear of the sample onto a third slide. Allow the smear to air dry. Observe the slide under high power of the microscope. Add a drop of immersion oil oil to the slide if 100x objective is to be used. Dead sperms, that is the sperm cells that were already dead in the fresh semen sample are stained pink in their head region while live sperms that is the sperm cells that were motile or immotile but alive in the fresh semen sample will remain unstained. Observe 100-200 random sperm cells and calculate the fraction of live and dead sperms in percentage. Normal semen sample contains more than 60% immotile but viable sperms. Viable sperms below 60% can be caused by excessive heat exposure of the testes, exposure to certain subtances that are toxic to sperms, certain infections etc. Necrospermia is a condition where there are no viable or living sperm cells in semen.