Electron microscope observations of nuclear evaginations in bronchial epithelium

Our plain-English summary of Electron microscope observations of nuclear evaginations in bronchial epithelium, by J. M. Frasca, O. Auerbach, V. Parks, et al (1965).

The study

• Authors: J. M. Frasca, O. Auerbach, V. Parks, W. Stoeckenius
• Published: Experimental and Molecular Pathology 4, 340-353 (1965)
• Type of article: Journal article
• Our copy: from Johns-Manville's own medical library. The article is still under copyright, so we describe it here rather than post it.

In plain English

This was a preliminary electron microscope report on human airway lining. It was not a study of asbestos: the article does not mention asbestos or any fiber exposure. The authors examined a piece of main bronchus taken just after lobectomy from four men at a Veterans Administration hospital in East Orange, New Jersey. Two had tuberculosis, one had a mucus-producing adenocarcinoma of the lung, and one had a squamous cell cancer of the bronchus. Under the light microscope, some ciliated lining cells held rounded vacuoles 1.5 to 4.5 microns across, above the nucleus. In a section about 1.0 mm long containing about 40 columnar cells, usually two to three such cells were seen. Under the electron microscope, these "vacuoles" were bounded by a double membrane like the nuclear envelope. Some were joined to the nucleus by a narrow neck and contained nuclear material, and some showed apparent breakdown of their envelope. The authors concluded that whether this is a normal cell process could not be answered convincingly with the available information. They noted that severe disease was present in all the lungs studied.

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: Descriptive light and electron microscope study of surgical tissue, presented by the authors as a preliminary report
• Who was studied: Bronchial tissue from four men who had lobectomies at the Veterans Administration Hospital, East Orange, New Jersey. One case (age unreadable in the scan) had a tuberculous focus. One was a 49-year-old man treated for chronic pulmonary tuberculosis. One was a 66-year-old man with a mucus-producing adenocarcinoma of the lung. One was a 68-year-old man with a well differentiated squamous cell cancer of the bronchus. Tissue was taken from the main bronchus at a site with no visible gross changes.
• Exposure: No asbestos or other fiber exposure was studied; the article does not mention asbestos
• Main results:
  • Under the light microscope, some ciliated cells contained one or more vacuoles above the nucleus, roughly spherical or ellipsoidal, with diameters between 1.5 and 4.5 microns
  • Vacuole-containing cells often occurred in groups of three to four cells. In a section about 1.0 mm long comprising about 40 columnar cells, usually two to three cells with vacuoles were found.
  • Under the electron microscope, the vacuoles were bounded by a double membrane identical in appearance to the nuclear envelope, and in some instances continuous with it, so they appeared to be outpocketings (evaginations) of the nuclear envelope
  • Nuclear material made of small dense granules and fine filaments usually filled the neck-like connection and, more diffusely, the whole vacuole
  • In some instances irregular openings were seen in the envelope of the evaginations, giving the impression of a local breakdown of the envelope
  • Cells with these structures usually did not differ otherwise from other ciliated cells. In some instances, tight aggregation of chromatin along the nuclear membrane, unusually dense cytoplasm and swollen mitochondria were observed.
• The authors' conclusion: The authors suggested that the blebs may dissolve and transfer nuclear material to the cytoplasm. They concluded that whether this is a regular part of the life cycle of bronchial epithelial cells could not be answered convincingly with the available information, and that more observations are needed.
• Limitations the authors state:
  • Severe pathological changes were present in all the lungs studied. Only tissue from apparently unaffected areas was used, but this cannot exclude pathological changes visible only at the electron microscope level.
  • Because continuous serial sections through whole vacuole-containing regions were technically difficult, the authors could not establish how often the connections to the nucleus occur, or whether completely separated vacuoles exist

Topics

Medical terms in this study, explained in our Lexicon: Epithelium, Bronchus, Adenocarcinoma, Squamous Cell Carcinoma, Columnar Cell.

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