Computer-Assisted Stereology: Point Fraction of Lung Parenchyma and Alveolar Surface Density in Fetal and Newborn Sheep

M.G. Davey, Ph.D., H.L. Hedrick, M.D., S. Bouchard, M.D., N.S. Adzick, M.D., A.W. Flake, M.D., E.J. Doolin

The Children’s Institute for Surgical Science and the Center for Fetal Diagnosis and Treatment, The Children’s Hospital of Philadelphia, Philadelphia, Pennsylvania, USA

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Summary: The aim of this study was to determine the accuracy of a new computer-assisted stereological technique in obtaining structural information of the lung. We compared the point fraction of lung parenchyma (P_p) and alveolar surface density (S_v) obtained by established manual point/intercept counting methods and compared them with those obtained using a computer-assisted method. Lung tissues obtained from normally grown fetal sheep (n=6) and from newborn lambs with severe lung hypoplasia (n=5) were inflation fixed via the trachea and processed for light microscopy. In verification-of-technique experiments, P_p and S_v correlated well with known values. There was a significant linear correlation between manual and computer-assisted stereological measurements for values of P_p (r² = 0.92) and S_v (r² = 0.98). Our data lead us to believe that the computer-assisted stereological technique described in this study provides accurate estimates of P_p and S_v and hence may be a valuable tool for evaluating the effects of factors upon structural development of the lung.

Key words: lung, surface density, surface area, fetus, stereology, sheep

PACS: 87.80.Pa