Friday, November 04, 2005

The time was about 2:45 and my boss and I were rushing through a collection phase in a project we were working on. We were rushing because it was a time sensitive deal: we had 15 minutes to finish it and start again with the next one. And we had already lost several minutes running down to the courtyard for a group photo. Maybe it was the added time pressure that caused this particular procedure to turn out as it did.

My boss and I are working to illuminate some fundamental anatomy of the brain. To do this it is necessary to poke at, inject into, and slice too pieces real, honest to goodness brains. The collections I mentioned above were of brains taken from mice that moments earlier had their brains inside their skulls and probably believed that they would stay there for some time. They were sadly mistaken. We worked in tandem because that was the best way for one to put the mouse down, collect our samples, and store the dissected pieces of brain in liquid nitrogen all in 15 minutes or less. We'd been doing this for a while so usually everything was taken care of with a minute or 3 to spare.

Not this time. This time we were already behind schedule (the chemical we'd injected often had an effect within 30 minutes, but now it was closer to 40) and we were trying to catch up. I injected the mouse with pentobarbital and watched as it wandered drunkenly in its enclosure and fall over. It was about 12 weeks old and fairly large. Attached to it was an intracerebral canula, which is kind of like a hat that it can never take off because it is attached to a hole in its skull. After a time I checked in the box and it wasn't moving about anymore, though it still seemed to be breathing. Generally about 2 minutes passed from pento to expiration and I wasn't sure how long it had been.

"He's down" I said, "but I think he's still breathing."

My boss checked the mouse and noted the heaving chest, "It is snap breathing, he is gone." Snap breathing is kinda of a spasm of the abdomen, not really drawing in breath. Basically she was telling me that despite appearances the mouse was, in fact, dead and so wouldn't feel what was about to happen to it. I bowed to superior wisdom. Normally at this point my boss performed a cervical dislocation: two fingers on the neck and another hand on the mouse's body. Force is applied in opposite directions and you hear a cracking sound. That way in case the pento didn't quite take the mouse is very definitely dead.

I can't recall if this maneuver was performed in this instance. As I said we were rushed.

My boss held the mouse by the head in one hand and a pair of scissors labeled, 'head' in the other. I held the mouse's body in my left and a large syringe in my right. With a snip the head came off and she went to work with it. I was focused on the arterial blood that spurted up and over the desk we worked on trying to suck as much of it into the syringe as I could and then put it on ice before it coagulated. I was also trying not to think about how much the headless mouse was moving about in my hand. I got about .7mls and dropped the critter-still wriggling into the bag.

That's when I noticed the head.

My boss had been distracted by our principal investigator-he's the guy that got all the expensive toys, our lab space, kinda tells us what to do, and hadn't removed the brain from the mouse yet. The head was rocking up and down, and with sufficient momentum I was worried it might fall to the flour. I looked closer, opened mouthed, and saw that the mouse's jaw was spasming open and closed trying to feed air into lungs that were now far far away. I watched it for a bit, and it lasted much longer then I felt it should. Actually I'm not sure if it was still before my boss finally returned to extract what was needed from it.

I wondered if it would hurt, if a decapitated mouse should happen to bite me.

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