Acute and Subacute Effects of Injury on the Canine Alveolar Septum: Results (4)

Acute and Subacute Effects of Injury on the Canine Alveolar Septum: Results (4)On the other hand, the prevalence of gaps in the septal interstitium of the two-week specimen was strikingly increased over that of controls (Fig 4; Table 4). Most of these gaps were occupied by type to severe emphysema which were produced by papain.
Gil and Weibel and Brain et al have shown the necessity of the vascular perfusion method of lung fixation, in order to preserve the alveolar surface lining and to maintain the alveolar macrophages in situ in the alveolar surface lining, findings we also have confirmed. This of course necessitates the removal of erythrocytes and leukocytes from the pulmonary vasculature, including the alveolar capillaries.
Montages of serial sections of whole alveoli were found to be essential for identifying relationships between septal gaps, epithelial cells and macrophages because a gap related to an alveolar cell or macrophage might appear on only one or two sections, whereas the cell often could be identified over an extent of 15 or more sections. This method severely limited the number of samples and hence the amount of lung tissue which could be studied because it is so laborintensive. The use of India ink as a marker allowed us to sample those areas of the lung parenchyma which the papain (or saline) had demonstrably reached.

Figure_4

Figure 4. Relative prevalence of type 2 cells and of type 2 cells in interstitial septal gaps per 1,000 ftm of alveolar surface area. C = control animals; S = saline control animal; P= papain-treated animals (with duration of time after treatment until sacrifice indicated below P). The solid line connects points representing the prevalence of type 2 cells in each specimen and the dashed line indicates the prevalence of type 2 cells in interstitial septal gaps. Note the similarity in patterns between total number of type 2 cells and number of type 2 cells in interstitial septal gaps.

Table 4—Prevalence of Pores and Gaps

Untreated Control A Untreated Control B SalineControl Papain 4 h Papain 2 Weeks Papain 4 Weeks
No. % No. % No. % No. % No. % No. %
Pores
Total No. 145 100 215 100 86 100 243 1(K) .54 100 29 100
No. associated with cells 19 13 49 23 71 83 24 10 46 85 22 75
No. located at alveolar 62 43 110 51 57 66 105 43 44 81 22 75
wall junctions
Other Septal Gaps
Total No. 22 100 54 100 29 100 45 100 115 100 49 100
No. associated with cells 19 86 27 49 15 52 29 64 100 86 45 92
No. located at alveolar 12 55 29 .53 15 52 27 60 90 78 45 92
wall junctions
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