Dear Stefan,

in my opinion the best way is to use the fact that the rat (and mouse) semen creates shortly after the copulation a solid vaginal plug. The plug can be found on the early morning in the mated females, extracted by the fine tweezers, and allowed them liquefy in cca 0.5 mL of saline.  It is necessary to place the male in the late evening together with some females. The willingness of the females to copulate depends on the oestral phase.

Best regards

Pavel

Thank you Pavel. Will you still be able to isolate sperm from that and if so will they be viable?

You are welcome. We used this method; the sperm was after the spontaneous liquefaction (approx. 0.5 to some hours) detectable and alive. Important is find the vaginal plug before the spontaneous liquefaction in vivo and transfer it immediately into the buffered saline. Best regards. Pavel

HI Stefan,

I agree with Pavel. Pulling out the vaginal plug is the best and the most easiest method.

Regards

Ralf

Electroejaculation will be a good option

I am sorry Stefan, I am only "working" with human beings, have no experience with rats!

In my own opinion  postcoital retrieval is the best option and effective. 

Hi Stefan,

I once succeeded to use a modified electro-ejaculation procedure to extract.sperm - what appeared was an extremely viscous mass like rubber and some sperm. Did not look useful. We subsequently managed to extract vaginal plugs very successfully after mating at night - but we only used this to check for successful mating and not for sperm extraction. So this may be the way to go to lyse the vaginal plug in medium

Thank you for all the valuable advice