Tuesday, 2 July 2013

Phony advice: "Just draw what you see"

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I got little enjoyment from, and had little natural ability at, peering down a microscope, and found it hard to make sense of what I saw down the instrument.

Therefore, it was very surprising to find myself a professional histologist (microscopic anatomist) for more than three years, as my interest in the human adrenal function led me into this realm.

I even had to teach this subject in practical classes - in the knowledge that the majority of students were simply copying the diagrams from their text books while pretending to draw what they could see.

Because, actually, almost the opposite is true: you can only see what you know is there.

And if you know something is there, then you will see it - especially when it comes to microscopes.

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Before each class I would project up microscope slides and point out the major features that students should look for in their own examples - and when it came to the adrenal I found a great deal of trouble in matching what I saw projected on screen, with what was in the textbook.

In fact I couldn't make sense of the slides at all, and can remember waving the pointer vaguely and rapidly across the projected slide while talking fast, and passing swiftly onto the next topic. 

Nonetheless, since the slides had been made in the anatomy department and had been used by generations of students, I naturally assumed that the fault was mine (as it normally would have been).

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It was not until I met a pathologist with an interest in anatomy that I discovered what was wrong.

In the first place the anatomy textbooks were wrong - they had the human adrenal shaped more or less like an egg, with a cortex surrounding the medulla like the white encloses the yolk.

Whereas the human adrenals were asymmetrical, being either flattened or somewhat pyramidal; and there was not much medulla at all; and what little medulla there was, was squashed and scattered (plus there was a whacking great, flaccid, central vein - and nobody had a clue what it did).

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So what was on the slides in the anatomy department?

As it turned-out - mostly pus.

The pathologist told me that the adrenal was one of the earliest parts of the human body to putrefy after death (second only to the pancreas) and indeed when death was painful and prolonged ('stressful') then the adrenal could become purulent even before death.

Therefore the only way to get post-mortem adrenals in decent condition was from rare sudden death victims (such as road traffic accidents) and within just a few hours of death.

By contrast, the post-mortem material in anatomy was from people dying of many causes and taken many days after death - so naturally, the adrenals were purulent.

So, in a nutshell, the students were being asked to draw carefully fixated and stained histological sections of rotten meat!

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The fact that, despite this, generations of anatomists had come up with labelled diagrams of text-book adrenals, proved conclusively that everybody involved - staff and students - was seeing and drawing what they 'knew' was there, and never what they actually saw.

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