PULMONARY MODELS 
220 
Electron micrograph of a bronchiolar epithelial cell. 
Orig. mag. 6400 X. 
piratory distress. She did not respond in this 
manner. 
Among the several parameters measured only 
the pulmonary arterial blood pressure varied 
significantly in three cows. In one of these three, 
alveolar septal degeneration and epithelial pro- 
liferation may have been related to the admin- 
istration of 1-tryptophan, or the condition may 
have preexisted. This cow was clinically refrac- 
tive. 
The precise etiology and pathogenesis of this 
ill-defined syndrome have yet to be elucidated. 
SUMMARY 
Eight cows were given intraruminal doses of 
d,l- and/or 1-tryptophan. None of the cows de- 
veloped clinical signs of acute bovine pulmonary 
emphysema. Among the cardiovascular, pul- 
monary and hematologic parameters measured 
on these animals the pulmonary arterial blood 
pressure increased significantly in three cows. 
In one of the three cows with increased 
pulmonary arterial pressure, alveolar septal 
degeneration and epithelial proliferation were 
observed in microscopic sections from a dia- 
phragmatic lobe. Ultrastructural studies sug- 
gested that the proliferated cells were derived 
from bronchiolar epithelium. 
ACKNOWLEDGEMENTS 
The technical assistance of R. C. Borgman, 
F. D. Giddings and A. E. Kilminster is grate- 
fully acknowledged. 
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DISCUSSION 
Aran Johnson, University of Michigan, 
Detroit : I'd like to know what steps you took to 
assure that the intravenous catheter was indeed 
placed in the pulmonary artery rather than, 
say going down in another vessel, or for that 
matter just looping around in the right ventricle 
and coming back into the atrium. 
