microwave processing problem

From:Steven Slap

Hi HistoNetters

Roxanne wrote:

Hello all---

I have been having a problem with my microwave technique for the past few
days.  I have been using the same protocol for months and out of the blue
days ago, the tissue looks fried.  The protocol is  as follows:

4 minutes in preserve at 55 degrees
4 minutes in p3 (alcohol blend) at 67 degrees
4 minutes in isopropol alcohol at 74 degrees
4 minutes in paraffin at 74 degrees

I have been thinking of trying a different fixative, but not so sure.

Some of the problems that we have had the past couple of days are completely
opposite of each other, but we will get very dried out tissue, fried looking
tissue, or tissue that doesn't look processed or fixed.  The protocol above
is for our small biopsies < 3mm.

Any suggestions???????????

It could be a lot of things....

1.  Do the biopsies sit in fixative for a suffiecient time in fixative on
the bench (at least 15 minutes) for the fixative to penetrate the tissue
before the microwave fixation step?

2.  Are the specimens all "true biopsies"  (needle biopsies, prostates,
GIs), or are some of them small pieces of tissue?  This program is very
short for tissue.

3.  What is the temperature of the paraffin when it goes into the microwave?
If too cold, the biopsies may be exposed to too much microwave energy unless
it is diverted by some sort of "dummy load."  If too hot, the biopsies may
be effected by exposure to the hot paraffin itself.

best regards,
Steven Slap

Marketing Manager/Microwave Product Specialist
Hacker Instruments & Industries, Inc.

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