The ultrastructure of asbestos bodies from guinea-pig lungs

Our plain-English summary of The ultrastructure of asbestos bodies from guinea-pig lungs, by J.M. Davis (British Journal of Experimental Pathology, 1964).

The study

• Author: J.M. Davis
• Journal: British Journal of Experimental Pathology
• Published: 1964;45(6):634-41
• Cited by: 32 articles, as counted by NIH iCite
• Read it: PubMed · Free full text

Abstract

The ultrastructure of the asbestos body has been examined in guinea-pigs treated with asbestos dust by the method of Holt and Young (1960). The first sign of asbestos body formation was the accumulation of dense granules approximately 60 A in diameter around the asbestos fibre. It is suggested that these granules are ferritin material. Usually the asbestos body coating consists of a single dense layer of ferritin, but sometimes low density layers are present that contain few ferritin granules. Often a whole series of layers is built up, but there is seldom any regularity in the thickness or density of these layers. The outermost zone of these bodies often consists of an irregular layer of radially arranged fibrous material but occasionally almost the whole body coat consists of these fibres which have a diameter of 50-60 A. A few asbestos bodies were found with a segmented appearance, but it seemed likely that this was due to the deposition of the ferritin as separate globules along the length of the asbestos fibre rather than as a smooth coating. There was no evidence of the breakup of asbestos bodies in guinea-pig lungs. In addition to the traditional asbestos body consisting of a neat core of asbestos fibre surrounded by coating material, a new structure was found that consisted of an irregularly shaped aggregate of ferritin around small scattered particles of asbestos dust. These structures often contained foreign material such as carbon particles in addition to the asbestos dust and ferritin. The significance of these new structures in relation to the classical asbestos bodies is as yet uncertain.

PubMed has no abstract for this study. This is the authors' abstract, copied from the article.

In plain English

This was an animal experiment that used the electron microscope to look at asbestos bodies, which are asbestos fibres that have become coated inside the lung. Guinea-pigs were exposed to chrysotile dust for 6 weeks, 18 hours a day, then killed at intervals up to 16 months later. The article does not state how many animals were studied. Asbestos bodies were found only in alveolar macrophages, in fibroblasts, or embedded among collagen fibres. The first sign of coating was small dense granules, about 60 angstroms across, gathering around the fibres. The author suggested these were ferritin, an iron-containing protein. Most bodies had a single ferritin coat. Fewer than a quarter were layered, and segmented bodies were rare. The segmented look seemed to come from coating laid down in separate blobs, and there was no evidence of bodies breaking up. Many fibres in the oldest animals had no coating at all. The author also described a new kind of irregular cluster made of ferritin and small chrysotile particles, whose significance was uncertain. Too few bodies were found for statistical analysis.

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: Animal experiment: electron microscope study of lung tissue from guinea-pigs exposed to chrysotile dust
• Who was studied: Guinea-pigs supplied by Dr. P. F. Holt of Reading University, killed at intervals after exposure, the last 16 months after removal from the dust tunnel. The number of animals is not stated.
• Exposure: Chrysotile dust in a dust tunnel for 6 weeks, with the dusting apparatus running 18 hours a day
• Main results:
  • Partly or completely formed asbestos bodies were found in only three places: alveolar macrophages, fibroblasts, or embedded among collagen fibres in areas of fibrosis
  • Apart from containing asbestos bodies, the macrophages and fibroblasts appeared normal
  • The earliest sign of body formation was dense granules about 60 angstroms across gathering around the fibre. Compared with known ferritin, the author judged it very likely that the basic coating material is ferritin.
  • Most bodies had a single layer of granular ferritin coating
  • Fewer than a quarter of the bodies examined were layered, and segmented bodies were comparatively rare
  • Only 21 bodies had a fibrous outer coating, and all of them were found in fibroblasts
  • Many uncoated fibres were found in the oldest animals, which must have had them in their lungs for at least 15 months. Some bodies were found after as little as 8 weeks.
  • The segmented appearance seemed to come from ferritin laid down as separate globules along the fibre, and there was no evidence of asbestos bodies breaking up in the guinea-pig lungs
  • A new structure was found: irregular aggregates of ferritin around small scattered chrysotile particles, often also containing material such as carbon particles
• The authors' conclusion: The author suggested that the granules forming the coating are ferritin, and stated that the significance of the new irregular structures, compared with classical asbestos bodies, is as yet uncertain
• Limitations the authors state:
  • Only a relatively small amount of material can be examined with the electron microscope, and too few bodies were found for statistical analysis
  • The finding that all fibrous-coated bodies were in fibroblasts may have been coincidence
  • The chemical nature of the low-density coating layers is uncertain

Topics

The National Library of Medicine indexes this study under subjects our site covers: Asbestosis.

Medical terms in this study, explained in our Lexicon: Asbestos Bodies, Asbestos Body Formation, Ferritin, Deposition.

Related studies

• The ultrastructure of asbestos bodies from human lung — J.M. Davis (1964)
• An electron microscopy study of the effect of asbestos dust on the lung — J.M. Davis (1963)
• The early effects of chrysotile asbestos dust on the rat lung — P.F. Holt, J. Mills, et al. (1964)
• The development of glass-fibre bodies in the lungs of guinea-pigs — S.K. Botham, P.F. Holt (1971)
• Numbers of asbestos bodies on iron-stained tissue sections in relation to asbestos body counts in lung tissue digests — V.L. Roggli, P.C. Pratt (1983)
• Exposure to asbestos and mesothelioma of the pleura — P.B. Fowler, J.C. Sloper, et al. (1964)

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