[Histonet] Ventana Tissue Processor

[KAELPERS <@t> aol.com]

I have had this problem before on two different type of processors.  I have 
researched and researched what could have happened....chemicals were placed 
appropriately, heat is applied only on the paraffin stations, processing times 
are standard...the only thing that I have came up with is that if you are 
processing very small delicate tissue directly after a complete change on the 
processor, the tissue is actually getting sucked dry by dehydration.  Look at your 
maintenance records again and see if the processor had just been completely 
changed out.
I just recently attended a seminar "The chemistry of processing and staining" 
and the lecturer referred to it as removal of the bonded water ...the bonded 
water is located at the cellular level (within the cell) and you do not want 
to remove this.  If the tissue is becoming over dehydrated it is removing this 
bonded water as well as the free water and is causing the tissue to shrivel up 
and in essence probably getting cooked.  
I have resorted to using sponges with tiny fragile tissue and doing partial 
changes if I know that I will be processing delicate tissue and so far this has 
worked out.
Another helpful hint in the event you would be cutting these tissue blocks is 
to soak the tissue blocks after faced in a cold glycerin solution...it will 
help tremendously with sectioning...although microscopically the outer edges 
will look "cooked".   Hope this helps.

lge