Ochs M, Nyengaard JR, Jung A, Knudsen L, Voigt M, Wahlers T, Richter J, Gundersen HJ.
Anatomy, Division of Electron Microscopy, University of Gottingen, Gottingen, Germany.
The number of alveoli is a key structural determinant of lung architecture. A design-based stereological approach was used for the direct and unbiased estimation of alveolar number in the human lung.
The principle is based on two-dimensional topology in three-dimensional space and is free of assumptions on the shape, size or spatial orientation of alveoli. Alveolar number is estimated by counting their openings at the level of the free septal edges, where they form a two-dimensional network.
Mathematically, the Euler number of this network is estimated using physical dissectors at a light microscopic level. In six adult human lungs, the mean alveolar number was 480 million (range: 274 to 790 million; CV: 37%). Alveolar number was closely related to total lung volume with larger lungs having considerably more alveoli. The mean size of a single alveolus was rather constant with 4.2x10(6) micro m(3) (range: 3.3 to 4.8x10(6) micro m(3); CV: 10%), irrespective of the lung size.
One mm(3) lung parenchyma would then contain around 170 alveoli. The method proved to be very efficient and easy to apply in practice. Future applications will show this approach to be an important addition to design-based stereological methods for the quantitative analysis of lung structure.
PMID: 14512270 [PubMed - as supplied by publisher]