RE: [Histonet] Microtome calibration

From:"Pamela Marcum"

We have a GLP person who is not familiar with Histology at all.  We have had
to educate her about these issues and may other things.  Calibration finally
came down to having a PM on the units every year.  After she understood all
the things we do with a section during the cutting phase and pick up that
would alter a true measurement. 

We also do MMA sections on the microtome and even those are next to
impossible to measure due to some stretching of the section during pick up
and drying.  Oh Yes, the drying of the slides really put her in a tail spin
as this was just not allowing the sections to stay the same as when they
were picked up.  

Sometimes a long talk and demonstration is the only way to make the point
that we are not standardized like clinical chemistry etc.  

Pamela A Marcum
University of Pennsylvania 
School of Veterinary Medicine
Comparative Orthopedic Laboratory (CORL)
382 W Street Rd
Kennett Square PA 19438

-----Original Message-----
[] On Behalf Of Rene J Buesa
Sent: Friday, October 31, 2008 10:08 AM
To: Dr. med. Frauke Neff
Subject: Re: [Histonet] Microtome calibration

That calibration is ussually done by measuring the advance mechanism of the
block holder and how many Ám the block moves towards the blade, but that is
RenÚ J.

--- On Fri, 10/31/08, Dr. med. Frauke Neff 

From: Dr. med. Frauke Neff 
Subject: Re: [Histonet] Microtome calibration
Date: Friday, October 31, 2008, 9:41 AM

Dear Dr. Girish,
I agree with rene, if the qualitiy of the cuts is fine it doesn't matter if
 are 1Ám or 2.3Ám thick.
But I'm highly interested in how your GLP auditors want to calibrate the
thickness of the section cuts. Are you supposed to measure the slides after
cutting?! Before or after stretching in the water bath?! If they have a
protocol how to do this I would be happy if they can share it with us.


Quoting Rene J Buesa :

> Dr. Girish:
> BOTH "requirements" are rubbish invented by bureaucrats with
lots of time in
> their hands and trying to appear concerned and knowledgeable.
> Thickness is not necessary as long as the section is diagnostically useful
> if some quantitative method as to the intensity is done in which case
> thickness = amount of matter, and would influence the outcome of the
> quantitative process.
> Timing the tissue processor is also totally irrelevant because it does not
> really matter a few minutes each way during a processing protocol. More
> important would be to keep a record of the fixation time that is the only
> step really critical in tissue processing.
> RenÚ J.
> --- On Fri, 10/31/08,  wrote:
> From: 
> Subject: [Histonet] Microtome calibration
> To:
> Date: Friday, October 31, 2008, 2:49 AM
> Dear all
> Is anyone practising microtome calibration for thickness of sections cut?
> Our GLP auditors are frequently asking for it.
> They also suggest that automatic tissue processor time in each reagent
> should be calibrated.
> any comments
> Regards
> Dr Girish
> India
> _______________________________________________
> Histonet mailing list

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