[Histonet] Cooling paraffin blocks with ice VS. Freezing Spray

[Jenny Vega]

Thanks everybody for your answers. I cant respond them all but I concluded
that the best way to get good sections is too chill the blocks on ice
because I agree that it facilitates the process.

I really don't understand why my supervisor depends so much on freezing
sprays to cut and the pathologist has never complained about artifacts
caused by them but I do believe that they are present because I have seen
them getting formed. It makes sectioning difficult because you try to get
sections free of holes and that contributes to the problem.

At my lab is the same thing. My supervisor is in charge of the embedding
and she just use the ice only for hardening the paraffin block. We don't
have a standard embedding center with cold plate. Since is a small lab we
just have a heating plate where we handle the specimens and place them in
the molds and we cool them on ice trays. After they are removed from the
molds they are placed on the counter in numerical order and they reach room
temperature and get warm. I do think that if they get cold and moistened
since the beginning it can facilitate the sectioning process except for
certain tissues that are not well processed. In my lab I change the
reagents in the tissue processor weekly but they get dirty too quickly
because we processes a lot of breast and colon tissue so is hard to get
perfectly processed tissue daily. We are under a tight budget and we can't
waste materials too quickly.

This situation with my supervisor has caused me a lot of frustration. I
have noticed that every tech has their own method to do things but
unfortunately there are people who are not receptive to new ideas and they
immediately criticize and say you are wrong specially if you are young and
you have recently started your career. I have though on several occasions
that all I learned in histotech school have been worthless because
everybody in the lab does things differently and this has made me question
my ability of being a good tech because I have experienced difficulty using
their microtomy technique but I have realized that I am not wrong.

Another issue was the use of microtome blades. Since I started my
supervisor has told me to use the minimum amount of blades as possible
because we are under a tight budget but I have noticed that some of those
blades are of poor quality and since we cut a lot of tissues that are hard,
calcified or have sutures they wear the blades too quickly. It's hard to
cut many blocks using  only one blade that you use to trim and section. I
have realized that I am successful obtaining good sections when I chill the
blocks on ice for a couple of minutes and change the blade immediately
after encountering difficulties with a block. It's not worth to sacrifice
the quality of the samples just to be cheap and save some money.


My supervisor is a great person and tech with a lot of experience but she
is not very open to new ideas. Her demands to save money can be unrealistic
when the correct technique is not being used . With her technique of course
you are going to waste excess of freezing spray and blades but she doesn't
understand this. Perhaps I need a change of environment which is
unfortunate but is difficult to work like this.


Thanks everyone for their input

On Sat, Sep 29, 2012 at 8:56 AM, joelle weaver <joelleweaver <@t> hotmail.com>wrote:

>  Jenny
>
> My experience and training is to use some method involving ice or at the
> very least a cold-retaining tray made to chill blocks. I also was taught
> this method in histology school , in clinical training at four quite
> large institutions,  and also have used some variation of an ice cooling
> method in every instance in my career working in clinical and research
> settings. There are always variations in technique from lab to lab, but
> freezing spray has been generally discouraged  for constant use at the
> microtome, since it can introduce artifact in sections if over used. ( It
> is pretty easy to see the effect on the face of the paraffin block, and
> that is not even under the microscope.) I actually almost never use
> freezing spray personally for regular paraffin microtomy. I  do use it when
> doing frozen sections on occasion, but then it is typically only for
> difficult specimens such as fatty breast or soft/fattty lymph nodes that
> need very cold temperatures. I sometimes use it to cool only the backside
> of paraffin blocks during embedding when I am being impatient, and I avoid
> spraying directly on the face, and that is about the extent it of freeze
> spray's uses for me.
>
> Personally, I prefer my blocks quite cold, in fact, one thing I don't like
> where I currently work , is that blocks are allowed to get to room
> temperature after removal from the embedding cold plate. I feel that I can
> more efficiently get good sections when the cold temperature is maintained
> and uniform though the block,  rather than re-cooling a warmed room temp.
> block.  Overall, I would expect constant and direct application of the
> freezing spray would be more of a problem than anything involving ice,
> which would "flash freeze" mostly the surface, and not cool throughout,
> which is why you have to keep spraying it.  Of course, I am not talking
> about leaving the faced block surface on the ice for so long a time that it
> becomes "water-logged"- but if you are sitting at your microtome and
> cutting diligently, and not leaving faced pecimens just sit there, I'm not
> sure how this would be an issue.
>
> In general I think the combination of ice and water benefits most
> specimens  ( especially GI and Liver cores, bloody stuff, and other
> types-that can sometimes be brittle and delicate due to processing)-I feel
> that the small amount of moisture that transfers from contact with the
> ice aids the smoothness/ reduces brittleness of the section,
> reducing "shatter" artifact. I feel that I would be unable to get sections
> without chatter in hard/dense tissues such as uterus body, cervix, bloody
> specimens and others without using ice. The only exception for me, might be
> brain which can cut better warm.
>
>  I am sure you must be frustrated, but if this is the clear direction of
> your supervisor, and they are not receptive to making any changes or
> allowing you to use your preferred technique, and not interested in
> new different methods,  then  I am not sure that there would be much that
> you can do other than comply with their policies. I know it is hard when
> people are not open to new ideas and techniques . I  had have
> that experience and  those feelings  quite often over the years, but just
> try to stay postive, do the best you can.
>
>
>
> Joelle Weaver MAOM, HTL (ASCP) QIHC
>
> > Date: Fri, 28 Sep 2012 22:39:31 -0400
> > From: histotech411 <@t> gmail.com
> > To: histonet <@t> lists.utsouthwestern.edu
> > Subject: [Histonet] Cooling paraffin blocks with ice VS. Freezing Spray
>
> >
> > I want to know what is your preferred method for cutting paraffin blocks
> in
> > the microtome everyday. At work I am having issues with my supervisor
> > because we have different ways of doing things like for example she
> doesn't
> > like to use the technique where you first trim the tissue, cool it on an
> > ice tray and then make a section. That is how I learned to cut in
> histotech
> > school. Instead she just trims and cuts the blocks at 4 microns one by
> one
> > using the same blade until it wears out and she cools the blocks only
> > freezing spray.
> >
> > She doesn't like to cool the blocks on an ice tray because according to
> her
> > is a waste of time and that is why I have to use her technique but
> > unfortunately some blocks are extremely difficult to cut and I have to go
> > back to my preferred technique. I feel I get better sections without
> > wrinkles when I chill and soak the blocks on ice for a couple of
> minutes. I
> > sometimes use freeze spray when the blocks get warm but when I cool them
> > with ice I don't need to use freeze spray that much. Her technique works
> > but is more successful when the blocks are well processed. I have
> > difficulty getting completed sections this way and spend more time trying
> > to get the perfect section. Sometimes I have my good days but other times
> > is tedious using this technique. Another thing I notice is that the
> blades
> > get worn down quicker when you use them to trim and section. I prefer two
> > separate blades, one to trim and the other one to section. I feel they
> stay
> > sharp for more time.
> >
> > She discourages the use of ice but then complains that we are running out
> > of freezing spray for the frozen sections too quickly which doesn't make
> > sense. It is obvious that if she encourages to use ice to cool blocks
> then
> > we will be using less freezing spray.
> >
> > Another reason she discourages the use of ice is that some blocks are not
> > meant to be chilled which is pretty understandable. I cannot cool small
> > biopsies such as gastric and skin and bone because they can get too hard
> > and tear off from the block so I avoid that but I prefer to cool breast
> and
> > colon biopsies on ice because these are fatty tissue that can be tedious
> to
> > cut even when relying only on freezing spray.
> >
> >
> >
> > I want to know if it's completely acceptable for me to prefer the trim,
> > cool on ice and section technique and if you feel is a waste of time
> > comparing it with other ways of cutting such as the one I mentioned.
> >
> >
> >
> > Thanks.
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