I was wondering too..

Wouldn't that be awesome! I've never heard of anything that does so. If they are not too big, I usually ignore them. Improving technique should minimize the number of bubbles, but this takes practice. Is it adult tissue or embryonic tissue? What kind of blade are you using? Some say low profile blades are better for thin sectioning onto slides.

Thanks everyone...It is during the collecting of cryosectioned adult tissue from the cryostat. i am using a high profile blade because I figured 20 mincrons wasn't too small - but maybe switching to a low profile will help - Thanks! I haven't coverslipped yet so it may not be a big deal - but didn't want the tissue to fold over with the cover slip for the big bubbles. One technique I've heard of is dipping the mounts in H2O for ten seconds then using the blade side of your palm and run it along filter paper on top of the mounts and slide to "iron out" the mounts. That doesn't really seem to be working - so was wondering if there were any other techniques out there. Thanks again!

I used really low temperature. -27, that way the tissue is really stiff. the slide itself should be cold too, so keep in inside the cryostat. then, Take the tissue with a brush and place it onto your slide, it is so cold that it will not stick right away, move it around if necessary to place it to its ideal location. then put your hot finger on the back of the slide and the tissue will slowly meld into the slide with absolutely NO BUBBLES GUARANTEE!!

Thanks i came up with it. please cite me.

Thanks Sandra - but I don't think I can go as low as -27...I find that my brain tissue shatters coming off the cryostat if it is any colder than -16 or -17 (maybe -20 depending on the day, but that'd be pushing it). I am cutting fish brain, so they seem to be a little more finicky than other tissues.

you can avoid bubbles by putting slices into PBS and then mounting them on slide....

I used room temp slides and utilized the melting of the freshly-cut cryo-sections onto the room temp slide to my advantage. Once cut, tap the bottom edge of the slide to the section. The section will start to melt/pull itself onto the slide. Pull the slide with this motion, sort of "stretching" the section out as it adheres. It ends up being a "down-ward and towards yourself" motion. Then immediately return to -20. I was using a 

- The slide should be kept in inside the cryostat.

- The section should be put directly on the zone of the slide where the finger is placed on the back. This difference in temperature will allow a good spread of the section.

- You have to repeat the operation for many times to assure a good result.