Microwave polymerisation of epoxy resin: rapid processing technique in ultrastructural pathology

Our plain-English summary of Microwave polymerisation of epoxy resin: rapid processing technique in ultrastructural pathology, by A.L. McLay, J.D. Anderson, W. McMeekin (Journal of Clinical Pathology, 1987).

The study

• Authors: A.L. McLay, J.D. Anderson, W. McMeekin
• Journal: Journal of Clinical Pathology
• Published: 1987;40(3):350-2
• Cited by: 10 articles, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text

Summary of the article

The authors tested whether microwave irradiation could polymerise epoxy resin when preparing tissue for electron microscopy. With conventional ovens this step needs at least half an hour. The work was done at the University Department of Pathology, Glasgow Royal Infirmary. Tissue fixed in 4% phosphate buffered glutaraldehyde went through a standard four and a half hour pre-polymerisation schedule and was embedded in EMIX resin in EMcap capsules. Control blocks were polymerised overnight (16 hours) in a 70°C oven. Test blocks were polymerised in a 400W Sharp microwave oven (Model R4060). Two primary tissue samples, fixed for more than 24 hours, were used. One fresh sample also received 60 seconds of microwave-assisted fixation. The microwave field was uneven, with a strong central zone. One minute or more in the centre caused almost explosive polymerisation and distorted the capsules. Consistent results came from capsules placed in a row at the front of the oven, given seven 15 second and two 30 second pulses separated by 30 second cooling intervals. Microwave and conventionally polymerised blocks from the same specimen, a secondary deposit of malignant mesothelioma, showed no noticeable difference in quality or cutting. Blocks more than 2mm across polymerised slightly unevenly. A lymphoma sample given both microwave fixation and polymerisation was of very acceptable quality. The authors concluded that microwave polymerisation is practicable, although its general usefulness remained to be established.

PubMed has no abstract for this study, and the article doesn't print one. We wrote this summary from the full article with the help of AI. It is not the authors' wording.

In plain English

This short technical paper from the University Department of Pathology, Glasgow Royal Infirmary, tested whether a microwave oven could be used to harden (polymerise) the epoxy resin in which tissue is embedded for electron microscopy. The control method was overnight (16 hours) heating in a 70°C oven. The paper did not study asbestos exposure or patients. The test tissue included a secondary deposit of malignant mesothelioma and a lymphoma. The oven's microwave field was uneven, and consistent results came from capsules placed in a row at the front. One minute or more of uninterrupted exposure caused almost explosive polymerisation in the centre of the oven and overcured, brittle blocks at the front. Short pulses instead (seven 15 second pulses and two 30 second pulses, separated by 30 second cooling intervals) gave acceptable and consistent polymerisation. For the mesothelioma tissue, microwave-polymerised and conventionally polymerised blocks from the same tumour showed no noticeable differences in quality. Blocks more than 2mm across polymerised slightly unevenly. The authors concluded that microwave polymerisation is practicable, but its general usefulness remained to be established.

We wrote this plain-English summary from the full article with the help of AI, and a second AI model checked each sentence against the article. It is not the authors' wording; the abstract and the article are their own account.

What the study did and found

• Design: laboratory technical methods study comparing microwave with conventional oven polymerisation of epoxy resin for electron microscopy
• Who was studied: Tissue samples, not people: two primary tissue samples fixed in glutaraldehyde for more than 24 hours, plus one fresh tissue sample given microwave-assisted fixation. Illustrated material came from a secondary deposit of malignant mesothelioma and from a diffuse centrocytic/centroblastic lymphoma. University Department of Pathology, Glasgow Royal Infirmary, Scotland; accepted for publication November 1986.
• Exposure: No asbestos exposure was studied. The test condition was microwave irradiation of resin-embedded tissue in a Sharp microwave oven (Model R4060, 400W, 2450 MHz). The control was heating overnight (16 hours) in a 70°C oven.
• Main results:
  • The microwave field in the oven was uneven, with a strong central zone. Consistent results were obtained with capsules placed in a row at the front of the oven.
  • Uninterrupted exposure for one minute or more caused almost explosive polymerisation with capsule distortion in the centre of the oven, and overcuring with brittle blocks at the front.
  • Seven 15 second pulses and two 30 second pulses, separated by 30 second cooling intervals, gave acceptable and consistent polymerisation.
  • In tissue from a secondary deposit of malignant mesothelioma, the microwave-polymerised block showed the same structures as clearly as the conventionally polymerised block from the same tumour.
  • Blocks more than 2mm across showed slightly uneven polymerisation. Marginally undercured blocks were hard in the centre but tacky on the surface.
  • A lymphoma sample given both microwave-assisted fixation and microwave polymerisation showed very acceptable quality.
• The authors' conclusion: The authors concluded that microwave polymerisation is practicable and might shorten rapid processing schedules without loss of quality, though its general usefulness remained to be established.
• Limitations the authors state:
  • The authors had not yet analysed field strength and distribution in detail.
  • The general usefulness of the technique remained to be established.
  • Resin infiltration, not polymerisation, is likely to limit how far total processing time can be reduced.

Topics

Medical terms in this study, explained in our Lexicon: Pathology, Malignant Mesothelioma.

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