Sperm Preparation
Two techniques for the purification and separation of semen are widely used: the swim-up method and the density gradient centrifugation method. Each method selects the most motile sperm from the sample for fertilisation. Both methods have shown that the motile sperm selected have significantly better morphology compared with sperm in the original semen sample.
- The density gradient method is rapid, requiring 20 - 40 minutes centrifugation, and is effective for all semen sample qualities.
- The swim-up method requires 30 - 60 minutes incubation.
Using the swim-up method the sperm are left intact and overlaid with medium (Sperm Preparation Medium) so that motile spermatozoa can "swim up" from the debris.
With the density gradient method (SupraSperm®), the sperm passes different gradients via centrifugation and the motile sperm are found in the final pellet. Current density gradient methods are based on coated colloidal silica particles.