Wednesday 19 March 2014

End of mouse issues

We're almost at the end of the Manual for Yr1 Biology practicals, two sections of which I've been teaching every week since September.  The last three sessions are mammalian anatomy and the mammal of choice is Rattus norvegicus the brown rat. None of "our" rats were brown of course: they were the product of many generations of genetic selection for calmness, genetic uniformity and coat-colour so were a mix of white and white with black heads.  None of "our" rats were white of course, they were pale yellow from the preservatives in which they had been vacuum-packed at the suppliers.  As I spoke my intro it occurred to me that rats are probably close to average size for mammals especially if you plot the data on a logarithmic scale.  There are 4000-5000 species of mammal and only a few of them are elephants, giraffes and whales; most mammals scurry about the floor of the forest often at night so we have a rather distorted view of the size-range, even with Attenborough talking breathlessly about their antics.

A few of the kids asked how their rat had met its untimely end, and I had to confess that I didn't know but I did say that asphyxiation with carbon-dioxide is horrible to watch.  As someone interested in end of life issues, I also told them that I had done for a lot of mice in my time by stunning and cervical dislocation - that's quick but only works if copious internal bleeding at the front end is irrelevant to your investigations.  At the time I was in the business of extracting, weighing and analysing biochemically their little adrenals.  Mice are small enough, their kidneys are smaller still - maybe the size of a mung-bean - and their ad-renals are about 2mm across and embedded in fat.  Nevertheless after many weeks of practice I could get through a lot of mice in a  couple of hours.  After a year I had a small-small result - not the one I was anticipating, but statistically significant - and wrote it up for the Mouse Newsletter. 

That set me off on a train of memory to a laboratory class I supervised while I was a graduate student in Boston.  It was, in essence, the same as we were doing in The Institute this week: mammalian (mouse Mus musculus there, then) anatomy for student nurses.  But the Course Director thought it might be handy to quadruple up the lesson to include injections, anaesthesia, and stages of death.  As a deeply institutionalised person I was just going to obey orders and follow my instructions.  I was, however, co-teaching this course with a pal of mine who had a moral compass and a far better crap-detector than me, and she put a stop to the Directors gallop.  It was clearly unethical to have student nurses offing small animals with phenobarbitone over-dose, quite apart from the likelihood of them stabbing themselves with the syringe.  In the end we agreed to do the experiment so long as the instructors (me and my pal P) did the injections.

The day arrived, I faced a class of twenty eager young nurses with a bottle of medicine, a syringe and a cage full of mice.  I had to work sharpish because everyone was raring to go and the class was only two hours long.  As I picked up the third or fourth rodent, it climbed up its own tail and sank its teeth into my finger. With a small cry of surprise , I shook my hand with a vigorous flicking motion that sent the mouse flying ptCHOINNNG  over two lab-benches into the midst of the students.  With as much dignity and speed as I could muster (without running in the laboratory) I followed after and fetched it off the floor from among the legs of the students. No shrieking here, they're nurses: well hardened to the shocking.  No reprieve, no second chance for that mouse I'm afraid.

We did the alimentary canal last week.  This week, it will be the urino-genital system.  Thats will be the time to talk about the adrenal glands.

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