Fig. 3

Example of pulmonary alveoli and microvessels as visualized through IDF videomicroscopy. (A) The light emitted by the Cytocam-IDF probe is reflected by the alveolar walls, which appear as a white line along the outer alveolar perimeter. The light is absorbed by hemoglobin in red blood cells, so that septal capillaries appear in dark grey color. Smaller acinar microvessels were not accurately explorable, therefore our analysis was focused on septal vessels. (B) Example analysis of alveolar dimensions in a segment of the whole image shown in A: yellow lines indicate the alveolar perimeters; the average diameters were then calculated by dividing the perimeters by π. (C) Blue arrows indicate septal microvessel diameters.