Mouse Perfusions

WARNING: This post may contain content that may not be suitable for all audiences. Do not read if you tend to have a sensitive stomach, become faint at the thought of blood, or have a love for mice.

Today work was definitely interesting. The goal of the day was to perfuse mice for later experiments. Basically what it means to perfuse a mouse is to knock it out with ether (not kill it, the heart has to still be pumping) pin it down, cut it open, and insert a tube into it's heart. All of the blood will then be pumped out, and then replaced with various clearing solutions. Once all the blood is removed from the mouse, it will eventually die, and we are able to use its organs (namely the brain, liver, spleen, intestine, and heart) without all of its blood.

So, with this in mind as the goal for the day...we got there this morning and prepared by making some different solutions and labeling and organizing tubes for the procedure.

After lunch, we finally got to do the actual perfusion. John and I didn't get to actually DO any of it today, we just had to take lots of detailed notes on the procedure so that we could do it next week on all of the extra mice. We had to wear face masks while we were doing the lab work so that we wouldn't contaminate the organs we were trying to preserve, which turned out to be a good thing in my case otherwise everyone else in the lab would have been laughing the entire time at my facial expressions.

The procedures are absolutely cruel. We literally suffocate the mice! They are sitting there, as innocent as they are, trying to play in the beaker until they pretty much fall over because they can't comprehend life anymore. Then, they're gasping for air the whole time (you can see it in their little bellies while you pin their hands down to the board). Layer by layer, their skin is cut off, until the organs are exposed, and then the protrude because the poor little mouse is trying so hard to get oxygen and be set free. Then we grab his heart, stick a needle in it, snip off another end, and watch the blood slowly run out, and slowly see the liver change to a ligher color.

After about 5 minutes of pumping the blood out, the mouse is totally dead. I still can't decide if I think this method of death is ethical or not. Everyone in the lab says "it's science" or "it's a lab mouse" or "he was bred for this". But I don't care. It's still hard to take. But I just get over it anyway. There's not much else I can do. I don't say much to anyone, it's mostly just all in my head anyway.

After the mouse is dead, we snip out all of the organs that we need. To get the brain, we cut off the head, remove the fur/skin, cut between the eyes, cut the skull from the sides, peel back the skull and remove the brain with tweezers. If it's completely white, then that means that the perfusing was done completely well. If there's still any pinkish color in the brain, then that indicates that there is still blood in the system (which isn't a huge deal, it's just a way to measure our success).

Anyway, sorry if that was too graphic for anyone.

John and I then got to practice brain cutting on our own. By brain cutting, I mean brains from mice, and they're being cut into slices (think meat in a deli). We have to use lots of dry ice, and different freezing/adhearing substances to get the brain to stick to the cutting block, and then we slice the brain in extremely thin slices (we're talkin in terms of nm here, so a brain about the size of a large lima bean we can get approx. 70 slices). John and I aren't very good at it yet. We didn't have too many good cuts. But, that's why we practice. We have about 20 brains to practice on, and if we need more, then we'll have to perfuse some more mice next week.