Some questions:

how thick are the tissues when you start processing,ie overall dimensions
of tissue? Whole or half heart, ???

You can extend processing, one of the first things to do, particularly in
paraffin and use vacuum/pressure IF you think paraffin infiltration is not
adequate. You did not say what kind of processor you use????  If your
tissues are normal sized 3 mm thick with automated processing, no heat
added (lends to more drying of animal tissue that is very lean,
particularly rodent), your schedule should work just fine.  

Common cause of holes in sections

1.Trimming the block with thick cuts, trim paraffin away more gradually

2.Oversoaking the tissue, then cutting a section - tissue can will pick up
water during   soaking, you can feel swelled tissue at block face after
long period in ice water

3.Improper processing, can try soaking carefully, or revisit your schedule,
change it.

With the new knife, more efficient for cutting a good, even, correct
thickness section, if you trim too thick, you gouge holes in tissue.  It
would show up in the next good section you cut.

also make sure your paraffin is not too hot for embedding - Tissue Tek
embedding center???





t 12:25 AM 1/26/70 -0500, you wrote:
>I am a technician in a research institution core facility.  My 
>question pertains to paraffin sectioning.
>When I cut rat heart tissue it looks like the paraffin has not 
>infiltrated.  There are many holes in the tissue.  This happens even 
>when I use a knew knife.
>   I use a Tissue Tek to embed the tissues.  The tissue go into the 
>alcohol for several changes of thirty minutes each.  The histoclear 
>steps are thirty minutes each too.  The paraffin changes are 30 mins, 
>1 hour, and 30 mins.
>Does anyone have any suggestions for embedding rat heart  and spleen 
>tissue?  I'm interested in a protocol that really allows for 
>infiltration into the tissues.   Thanks for your help
>
>
>
Gayle Callis
MT,HT,HTL(ASCP)
Histopathology Supervisor
Veterinary Molecular Biology
Montana State University - Bozeman
Bozeman MT 59717-3610

406 994-6367
406 994-4303 (FAX)