(a) An example diagram showing the concept of the point-counting method of Lm (mean linear intercept). Fixed-length linear lines were drawn randomly on alveoli. The length was divided by the number of points crossing alveolar septa giving the average of alveolar septum distances. (b) Typical pathological findings of lung from each group (100×) for counting of Lm and number of arteriole (mm−2). The top specimen showed the destruction of alveoli in pulmonary emphysema. The grid was covered by 1000 µm × 1000 µm. Lm was determined using this grid and crossing alveolar septum (details are given in §2). The arteriole is circled. The number of arteriole was also counted within a square of 1000 µm × 1000 µm. The number of arteriole was lower in PE.