Ultrastructure of mesothelial regeneration after intraperitoneal injection of asbestos fibres on rat omentum

Our plain-English summary of Ultrastructure of mesothelial regeneration after intraperitoneal injection of asbestos fibres on rat omentum, by S. Gonzalez, J. Friemann, K.M. Müller, et al (Pathology, Research and Practice, 1991).

The study

• Authors: S. Gonzalez, J. Friemann, K.M. Müller, F. Pott
• Journal: Pathology, Research and Practice
• Published: 1991;187(8):931-5
• Cited by: 1 article, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

In order to describe the ultrastructural features of the early phases of regenerating mesothelium in rat peritoneum, 69 cases were examined after intraperitoneal injection of 0.05-15 mg crocidolite, chrysotile B and other mineral and synthetic fibers. The findings show the presence of intermediate or transition cells between proliferating submesothelial connective tissue cells bearing the ultrastructural phenotype of myofibroblasts and mature fully regenerated mesothelium. Our results and data accumulated in the literature provide strong support for the hypothesis of submesothelial cells origin for regenerating mesothelium.

In plain English

In this animal experiment, the authors used electron microscopy to study how the lining of the rat abdomen (the mesothelium on the omentum) regrew after asbestos was injected. They examined 69 cases. Of these, 64 were female Sprague-Dawley rats given one abdominal injection of 1 to 15 mg of crocidolite (32 rats) or chrysotile B (32 rats) and killed 8 hours to 15 months later. Tissue from 5 female Wistar rats in 25-month studies of natural and man-made mineral fibres was also included. Findings were similar in both experimental groups. In the first week, no lining cells were visible on the surface. From 2 weeks to 6 months, thin undifferentiated cells partly covered it. In places, layered cells looked like immature lining cells, with myofibroblast-like cells beneath them. After 6 months, before mesothelioma had fully developed, layered lining-type cells covered the surface. Asbestos fibres were not found near the proliferating cells. The authors concluded that their findings and earlier literature strongly supported the idea that regrowing lining cells come from cells beneath the surface.

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; omentum tissue examined by transmission electron microscopy
• Who was studied: 69 rats: 64 female Sprague-Dawley rats killed 8 hours to 15 months after injection, plus omentum specimens from 5 female Wistar rats in long-term (25-month) carcinogenicity studies
• Exposure: One intraperitoneal injection of 1 to 15 mg crocidolite (32 rats; South African) or chrysotile B (32 rats; Canadian), both UICC reference samples, in 1 ml saline. The 5 Wistar rats received natural and man-made mineral fibres; figure legends mention 0.05 mg actinolite.
• Main results:
  • The ultrastructural findings were similar in both experimental groups.
  • Early phase (8 hours to 1 week after injection): mesothelial cells were not visible on the omental surface.
  • Intermediate phase (2 weeks to 6 months): the surface was partly covered by thin, elongated, undifferentiated cells. In other areas, a layered set of spindle cells showed features of immature mesothelium, with myofibroblasts and fibroblasts beneath.
  • Proliferative mesothelial phase (after 6 months, before full development of mesothelioma): the surface was covered by a layered sheet of cells showing mesothelial differentiation, resting on a partially fragmented basal lamina.
  • Asbestos fibres were not found near the proliferating submesothelial or mesothelial cells in any case.
• The authors' conclusion: The authors concluded that their findings, together with earlier literature, gave strong support to the hypothesis that regenerating mesothelium originates from submesothelial cells.

Topics

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

Medical terms in this study, explained in our Lexicon: Omentum, Mesothelium, Peritoneum, Crocidolite, Chrysotile.

Related studies

• Mesothelial proliferation due to asbestos and man-made fibres. Experimental studies on rat omentum — J. Friemann, K.M. Müller, et al. (1990)
• Acute and chronic effects of intraperitoneal injection of two types of asbestos in rats with a study of the histopathogenesis and ultrastructure of resulting mesotheliomas — M.L. Shin, H.I. Firminger (1973)
• P53 mutations in tumours induced by intraperitoneal injection of crocidolite asbestos and benzo[a]pyrene in rats — K. Unfried, N. Kociok, et al. (1997)
• Mesothelioma dose response following intraperitoneal injection of mineral fibres — J.M. Davis, R.E. Bolton, et al. (1991)
• An assessment of the fibrogenic potential of two refractory fibres by intraperitoneal injection in rats — G.H. Pigott, J. Ishmael (1981)
• Asbestos in extrapulmonary sites: omentum and mesentery — R.F. Dodson, M.F. O'Sullivan, et al. (2000)

Browse more research in Pathology, Research and Practice, or return to medical research.