[Histonet] Soaking paraffin blocks

[Nicola Cragg]

I have read with interest the discussion on soaking paraffin blocks and
with fear of being struck down by hell, fire and damnation - Kemlo I
have to admit I'm in the UK and I do it!!  At least with some tissues -
in particular intestinal bundles.  After chilling blocks on the
coldplate I sit them face down on ice with a little water (have a
plastic tray in the freezer with ice in it).  I routinely cut blocks
containing 6 bundles of intestine, each bundle contains approx. 16
pieces of intestine all orientated end on to get numerous cross-sections
through the intestine - they cut a lot easier after being sat on the wet
ice and I have no complaints on the quality of my sectioning.

What am I concerned with is the claim of poor processing - how does one
know that it is poor processing, particularly if you haven't seen the
blocks or attempted to cut them?  What is poor about it - insufficient
wax penetration, lack of dehydration?  Processing is essentially quite a
straight forward process and apart from varying timings in alcohols,
xylene and wax, I can't understand how it could go so wrong?!!  I have a
Leica TP1020 without vacuum and run overnight schedule based on what
I've read up - reagents are changed regularly always erring on the side
of caution.  

I am a self-taught histologist (and there may lay your accusations -
LOL) and have been "practicing" for over 5 years now, but I have only
learnt by reading up on what the experts say and do (including Histonet
- which I have found to be a fantastic tutor) and by practice.  I am
always keen to learn from my more experienced peers so please expand on
pharses such as "poor processing" and "poor fixation".





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