I feel terribly privileged when I'm
handling human brains these this tissue
is something requested to us for
research purposes and it's an honor to
be able to handle the tissue and meet
that request
my name's steve gentleman i'm the
professor of new pathology and Imperial
College in London and one of my job's is
to carry out the diagnostic assessment
of the brains that come into our tissue
bank
the first thing you do when you get the
brain is to examine the external
features of the brain to see if there's
any clue there as to what might have
gone on so you look at the surface of
the brain the membranes that cover the
brain is there any evidence of any
infection we then look at the patent on
the surface of the brain at the folding
to see if that's normal and whether
there's any shrinkage or atrophy in any
particular areas also feel the brain to
see if there's any softening because if
there is a soft area that may indicate
there was a stroke in that area then
look at the blood vessels at the base of
the brain and they will give us some
clues as to lifestyle factors that may
have been involved they may be
atherosclerosis or hardening of the
arteries
due to a high-fat diet or smoking or
lack of exercise all may contribute to
this type of change
when we have a whole brain fixed in
formalin what we will do is we will make
a cut through the brain stem which is
that part of the brain which is quite
small but very important in carrying out
all of those everyday functions that we
will rely on without thinking about too
much
we separate the brain stem and the
cerebellum from the rest of the brain
in order to carry up the neuro
pathological examination in a
reproducible fashion we have to cut up
the brain in a fairly stereotypical way
so we use a single point for our first
cut we have a landmark called the
mammillary body that's a part of the
brain involved in housekeeping functions
and we use that as our guide for the
first cut using a rather large bread
knife if you like that's what it looks
like
we then slice the brain up into what we
call coronal sections and then space
those out so that we can have a look
through the whole extent of the brain to
look for any pathology and then to take
some representative blocks so that we
can follow up and look down the
microscope at what's going on and in
this way we can build up a diagnostic
report of what the problem was with that
particular patient and this is very
important because the tissue then goes
out to researchers and they no need to
know exactly what was going on
we cut these sections using a guide
because there are some parts of the
brain that we need to look at which are
quite small so we have to accurately
make a half centimeter slice
when all these slices are laid out in a
logical fashion you can inspect each
slice individually working from the
front to the back of the brain just
checking that all the structures are as
you would expect them to be looking for
any signs of change whether it be in
multiple sclerosis for example there may
be changes in the color of parts of the
brain we then have to sample 20 specific
anatomical areas to allow us to take
them away to be stained and look at them
down the microscope to try and work out
which pathologies are there because it's
not always just one pathology we have to
make sure if there are multiple
authorities that we write that down and
again it's very important for the
researcher they need to know everything
that's gone on in the brain the samples
we take are put into small plastic
cassettes and these are then embedded in
paraffin wax and the reason we do this
is to get very very thin slices to look
at under the microscope we need to mount
the tissue in something that can be cut
so those are cut at about 6 microns
which is very very thin it allows us to
look at the tissue
I've been looking at brains for 25 years
now and I have probably examined over a
thousand every brain is individual when
I first pick up the brain what I'm
looking at is the external features and
if you like the convolutions of the
brain are a little bit like a
fingerprint they're unique to the
individual obviously they have a very
similar general structure but there are
subtleties we're all slightly different
in our development so no two brains are
the same
and indeed that applies to the pathology
as well Parkinson's disease is very well
described disease when in fact the
pathology you see in the brains of
people who've had Parkinson's disease
it's very individual
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