I'm not an expert but in my opinion you have to do that in order to facilitate the colection. It is hard to pick spermatozoa when they are moving

Hi David , 

Ah thats really not the answer other wise you can pick the dead sperm only if molility is the criteria

Regards

AJ

Hi Aamir, 

first of all, you have to choose a motile spermatozoa, after that your have to touch the spermatozoa selected.This process will stop the spermatozoa and then you could aspirate it