Microwave fixation versus formalin fixation of surgical and autopsy tissue.

Author(s): Login GR

Publication: Am J Med Technol, 1978, Vol. 44, Page 435-7

PubMed ID: 354379 PubMed Review Paper? No

Purpose of Paper

The purpose of this paper was to determine the effects of fixation technique and fixative type on a variety of surgical and postmortem tissue specimens.

Conclusion of Paper

Morphological preservation in specimens fixed by microwave oven fixation in saline or Zenker's fluid was equal or superior to that in specimens fixed by all other fixation techniques and solutions in this study. Preservation of morphological details was comparable in specimens fixed by microwave fixation in formalin and vacuum oven formalin fixation. Microwave oven fixation to a temperature of 55 degrees C and fixation at temperatures above 63 degrees C were inferior to fixation at 60 and 63 degrees C in regards to morphological preservation.

Studies

Study Purpose

The purpose of this study was to determine the effects of fixation in a plastic tissue cassette in a microwave oven with fixation in a metal tissue cassette in a vacuum oven as well as fixative type on the morphological quality of 15 different surgical and postmortem tissue specimens, including fibrous connective tissue. After microwave fixation, 2 hours of formalin baths were eliminated from tissue processing.

Summary of Findings:

Morphological details were superior in specimens fixed by microwave irradiation (60 degrees C, 80 seconds) in saline compared to those in specimens fixed by microwave irradiation in formalin or distilled water and at least equal to those specimens fixed by vacuum oven (63 degrees C, 3 hours) in formalin. Further, specimens fixed by microwave irradiation in saline did not show the shrinkage that was characteristic of the vacuum oven formalin fixation. Specimens fixed by microwave irradiation in Zenker's fluid had comparable morphology to those fixed by microwave irradiation in saline and at least equal to specimens fixed by vacuum oven in Zenker's fluid. Specimens fixed by microwave irradiation in distilled water resulted in slightly lower quality staining than those fixed by vacuum oven in formalin and showed swollen tissue and cells. Morphological details in specimens fixed by microwave irradiation in formalin were comparable to specimens fixed by vacuum oven formalin fixation with slight cellular shrinkage. Morphology in specimens fixed by microwave oven irradiation to a temperature of 60 degrees C was superior to those fixed at 55 degrees C, but fixation at temperatures above 63 degrees C resulted in fracturing artifacts during sectioning and pyknotic nuclei.

Biospecimens

Preservative Types

Formalin
Other Preservative

Diagnoses:

Autopsy
Not specified

Platform:

Analyte	Technology Platform
Morphology	H-and-E microscopy

Pre-analytical Factors:

Classification	Pre-analytical Factor	Value(s)
Biospecimen Preservation	Duration of tissue/ specimen processing	6 h 8 h
Biospecimen Preservation	Method of fixative delivery	Microwaved Vacuum oven
Biospecimen Preservation	Temperature of fixation/preservation	55 degrees C 60 degrees C 63 degrees C Above 63 degrees C
Biospecimen Preservation	Time in fixative	80 sec 3 h
Biospecimen Preservation	Type of fixation/preservation	Formalin (buffered) Microwave irradiation Saline Zenker's fluid
Storage	Type of storage container	Plastic tissue cassette Metal tissue cassette

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