Journal of Applied Physiology, Vol 65, Issue 4 1592-1597, Copyright © 1988 by American Physiological Society
Morphometric measurement of local curvature of the alveolar ducts in lung mechanics
D. A. Silage and J. Gil
Department of Electrical Engineering, Temple University, Philadelphia, Pennsylvania 19122.
We have performed partial serial reconstructions of an acinus of the rabbit
lung and determined the apparent existence of numerous heterogeneities in
length, diameter, and local curvature in individual generation branches of
the lung. We believe that structural changes during respiratory movements
may include changes in the length and diameter of the whole duct. Alveoli
are seen to be side differentiations secondary to the ducts in the
gas-exchanging parenchyma of the rabbit lung. We have developed a technique
for measuring local curvature in simple reconstructed ducts from the
average of the integral curvation of the section contour. The contour
curvature is measured from the chain code representation of the sampled
contour from digital image analysis. The stereological requirements of an
unbiased and random selection of contours is approached here by the random
orientation of the individual alveoli of a single duct. Over 700 sections
through the last four airway generations (alveolar ducts) at 3-micron
intervals were analyzed. The average integral curvature ranges from 7.7 to
9.5 (mean 8.9) mm-1 for sixth- and seventh-generation branches from the
start with volumes for the segments from 0.022 to 1.198 (mean 0.497) mm3.
