Sectioning and imaging hard mineral fibres in biological tissues

Our plain-English summary of Sectioning and imaging hard mineral fibres in biological tissues, by N.F. Johnson, K. Ibe (Journal of Microscopy, 1981).

The study

• Authors: N.F. Johnson, K. Ibe
• Journal: Journal of Microscopy
• Published: 1981;122(Pt 1):87-92
• Cited by: 5 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

A technique is described which overcomes the problems associated with sectioning biological tissue containing hard mineral fibres. 0.2--0.5 micrometer thick sections were cut with a diamond knife, placed in a folding grid, conventionally stained with uranyl acetate and lead citrate and viewed at an accelerating voltage of 200 kV in the scanning transmission mode.

In plain English

This laboratory methods paper, from the MRC Pneumoconiosis Unit in Wales, described a way to cut and view slices of biological tissue containing hard mineral fibres so that the fibres did not tear or fall out. The authors used lung tissue from rats that had inhaled UICC crocidolite or UICC amosite for 23 to 26 weeks, and macrophages (scavenger cells) grown with UICC crocidolite fibres. Conventional slices 60 to 90 nanometres thick showed scores, holes and displaced fibres. Thicker slices, 0.2 to 1.0 micrometre, cut with a diamond knife kept the fibres in place. Cutting flaws still occasionally appeared in thinner slices, and resin sometimes pulled away from coarser fibres. Thick slices gave poor images in standard transmission mode at 100 kV. Viewing at 200 kV in scanning transmission mode gave what the authors judged the best image. Slices of 0.3 to 0.5 micrometre were most useful. The authors reported fibres inside cells, both in vacuoles and free in the cytoplasm. They concluded thick sections gave more information than replication techniques.

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 methods paper (electron microscopy technique development) using tissue from an animal inhalation experiment and cultured cells
• Who was studied: Lung tissue from rats exposed by inhalation to UICC crocidolite or UICC amosite for 23-26 weeks, and lavaged unstimulated macrophages grown in culture; work at the MRC Pneumoconiosis Unit, Llandough Hospital, Penarth, Wales. The number of animals is not given.
• Exposure: Rats inhaled UICC crocidolite or UICC amosite. Cultured macrophages were incubated for 18 h in medium containing UICC crocidolite fibres. The concentration is printed in the scan as '60 pg ml 1', most likely 60 micrograms per millilitre.
• Main results:
  • Conventional sections 60-90 nm thick containing fibres had scores, holes and displaced fibres
  • Sections 0.2-1.0 micrometre thick cut with a diamond knife retained the fibres in place
  • Cutting artefacts still occasionally occurred in the thinner sections, and resin sometimes separated from coarser fibres
  • Viewing both surfaces in scanning mode showed whether fibres lay within the section (dull, indistinct outline) or on its surface (bright, sharp outline)
  • In conventional TEM mode at 100 kV, images of thick sections were generally of low brightness, resolution and contrast
  • Comparing imaging conditions on the same section, STEM mode at 200 kV gave the best subjective image with the most ultrastructural information
  • At 200 kV the tissue's inherent contrast was lower and staining was more critical
  • Sections of 0.3-0.5 micrometre were most useful because they consistently retained the fibres in place
  • Analytical procedures were possible on the thick sections
  • Fibres were seen inside cells, both in vacuoles and free in the cytoplasm
• The authors' conclusion: The authors concluded that thick sections give information superior to techniques relying on replication of surface structures of dewaxed tissue sections
• Limitations the authors state:
  • Improvements in image quality were judged subjectively
  • Cutting artefacts and resin separation from coarser fibres still sometimes occurred

Topics

The National Library of Medicine indexes this study under subjects our site covers: Amosite, Crocidolite.

Related studies

• The detection and localization of mineral fibers in tissue — C. Berkley, J. Churg, et al. (1965)
• Determination of mineral fibre in human lung tissue by light microscopy and transmission electron microscopy — A.J. Rogers (1984)
• Macrophage functions after exposure to mineral fibers — F. Tilkes, E.G. Beck (1983)
• Comparing biological effects of mineral fibres — J. Dunnigan (1989)
• Comparing biological effects of mineral fibres — J.M. Meijers (1990)
• Cytotoxic effects of some mineral dusts on Syrian hamster peritoneal macrophages — E. Bey, J.S. Harington (1971)

Browse more research in Journal of Microscopy, or return to medical research.