Frequently Asked Questions: Sil-Select StockTM

FAQ1: Can we make our own gradients using Sil-Select Stock TM?
Yes you can. Sil-Select StockTM is an isotonic stock solution of our silica based density gradient. To make your own gradients simply add adequate amounts of FertiCultTM Flushing medium to make up the correct dilutions.
Note that the use of HEPES buffered dilution media is strongly encouraged to ensure a stable pH.

FAQ2: Should the whole bottle be prewarmed each time? How long can I use Sil-Select StockTM after opening the bottle?
We have performed in-use testing on Sil-Select StockTM which supports the use of the media up to 7 days, taking into consideration that the bottle was opened under sterile conditions and the product was stored at 2-8°C after opening. In addition and as indicated in the IFU it is advised to:

  • keep the product in its original container until the day of use and
  • depending on the number of procedures that will be performed on one day, remove the required volume of medium under aseptic conditions in an appropriate sterile recipient. Only prewarm this recipient. This is in order to avoid multiple openings/warming cycles of the medium. Discard excess (unused) media.

FAQ3: How long after liquefaction can density gradient centrifugation be performed?
Density gradient centrifugation should be performed as soon as possible.

FAQ4: Which medium should be used for washing after performing density gradient centrifugation?
FertiCultTM Flushing medium or Sil-Select PlusTM Sperm Washing/Insemination medium.

FAQ5: How to handle a bad semen sample with a volume larger than 2.5mL?
Use more than one tube, with a maximum of 100 million cells per tube. Do not change the ideal volume ratio of 2.5ml semen – 2.5ml 45% gradient – 2.5 ml 90% gradient! The gradient/semen can be centrifuged for an additional 5-10 minutes (total of 23-28 min @ 400g). 80% gradient might be used instead of 90% gradient (more sperm cells will pass through the layers).

FAQ6: How to resuspend the pellet after centrifugation?
Use a syringe, pasteur pipet or micropipet. Avoid vortexing because this can harm the spermatozoa.