The normal human lung: ultrastructure and morphometric estimation of diffusion capacity

https://doi.org/10.1016/0034-5687(78)90104-4Get rights and content

Abstract

Eight normal human lungs, obtained from patients dying of causes not involving the lung. were totally fixed in situ by instillation of a glutaraldehyde solution into the airways shortly post mortem. The age range was 19–40 years, average body weight was 74 kg and the average lung volume 4300 ml. Stratified random samples from twelve regions were morphometrically studied by electron microscopy using stereological methods. The fine structure of the human lung parenchyma as seen by scanning and transmission electron microscopy is described.

The alveolar surface area was found to be 143 m2 on the average (± 12); this value is 75% higher than previous light microscopic estimates mainly because of higher resolution of the electron microscope thus leading to a different definition of ‘alveolar surface’. Capillary surface area and volume were 126 m2 (±12) and 213 ml (± 31), respectively. The arithmetic mean thickness of the human air-blood tissue barrier was estimated at 2.2 μm (±0.19) and is thus considerably thicker than that found in other mammals: the same holds for the harmonic mean thickness of the barrier (0.62 μ±0.04). This appears to be related to a particularly large amount of connective tissue fibers found in the human alveolar septum.

From this morphometric information total pulmonary diffusion capacity for 02 was calculated; using the set of largest and smallest physical coefficients we obtained respectively a maximal value, DLmax = 263 ml O2/min ·mm Hg (±34), and a minimal value, DLmin = 125 (± 18). These data relate to the totally inflated and unfolded lung; if they are corrected to account for ‘available’ gas exchange surface, reduced because of the presence of an alveolar extracellular lining, we obtain for ‘available’ diffusion capacity : DLmax*= 130–190 and DLmin* = 62–91 ml O2/min·mm Hg respectively. These corrected values seem to agree with physiological estimates of human dl in exercise.

References (41)

  • M. Bachofen et al.

    Postmortem fixation of human lungs for electron microscopy

    Am. Rev. Respir. Dis.

    (1975)
  • J. Bitterli et al.

    Repeated measurements of pulmonary O2 diffusion capacity in man during graded exercise

  • H. Burri et al.

    Morphometric estimation of pulmonary diffusion capacity. II. Effect of environmental po2 on the growing lung

    Respir. Physiol.

    (1971)
  • P. Gehr et al.

    Morphometric estimation of regional differences in the dog lung

    J. Appl. Physiol.

    (1974)
  • P. Gehr et al.

    Elektronenmikroskopie und Morphometrie der menschlichen Lunge

    Acta Anal.

    (1975)
  • P. Gehr

    Die menschliche Lunge im Rasterelektronenmikroskop

    Acta Anat.

    (1976)
  • P. Gehr et al.

    Effects of optical resolution on the estimation of stereological parameters

  • P. Gehr et al.

    Elektronenmikroskopie und Morphometrie der Pferdelunge

    Ada Anal.

    (1977)
  • P. Gehr et al.

    Comparative morphometric analysis of large mammaliann lungs

    Experientia (Basel)

    (1977)
  • P. Gehr et al.

    Adaptation of the growing lung to increased V̇O2. The effect of exposure to cold environment in rats

    Respir. Physiol.

    (1978)
  • Cited by (468)

    View all citing articles on Scopus

    This study was supported by grant 3.394.74 from the Swiss National Science Foundation.

    View full text