Acute and Subacute Effects of Injury on the Canine Alveolar Septum: Results (1)

Light Microscopy
There was an influx of polymorphonuclear leukocytes into the lungs of the 4-h saline and 4-h papain dogs, into all three compartments of the alveolus: the airways, the capillaries and the interstitium. This was more pronounced in the normal saline dog, but prominent also in the 4-h papain dog where it was accompanied by hemorrhage, whereas in all other specimens (control, two-week, and four-week papain) polymorphonuclear leukocytes and hemorrhage were rare.
Severe emphysema was identified by light microscopy (and also by scanning electron microscopy) in the right lungs of the two animals into which papain had been instilled two and four weeks earlier (Fig 1).
An attempt was made to quantify the distribution of alveolar macrophages and type 2 cells either at sites of junctions of alveolar walls or in the areas between junctional sites by examining multiple sections from random areas of all six lung specimens. In the papain-treated animals, this was made difficult because of the abnormal histologic appearance of many areas. In the specimen obtained 4 h after papain instillation, alveolar wall outlines and alveolar cells could not be identified with certainty in many areas because of severe intraalveolar hemorrhage. In the specimens obtained two and four weeks after papain instillation, similar problems of identification were encountered because of the presence of abnormally enlarged airspaces in many areas, with increased interstitial cel-lularity. Nevertheless, an assessment of recognizable alveoli also was made in these specimens. buy ortho tri-cyclen


Figure 1. Scanning electron microscopic appearances of lung specimens: A, saline control specimen; B, 4 h after papain instillation; C, two weeks after papain instillation; D, four weeks after papain instillation. Note appearance of gross emphysema in C and D.