Effect of atmospheric ammonia on the surface ultrastructure of the lung and trachea of broiler chicks.

The surface ultrastructure of the lung and trachea of 7-week-old broiler chicks were examined with scanning electron microscopy (SEM) to obtain a more accurate understanding of structural changes due to atmospheric ammonia (NH3). In the first experiment, four broilers were randomly assigned to each of four chambers, and exposed to 0, 25, 50, 75, or 100 ppm NH3 for 7 days. Chickens exposed to 100 ppm NH3 exhibited a large number of mucus-secreting cells that were not seen in the other treatments. Ciliary loss from the tracheal epithelium was not a consistent finding in either the exposed or the control groups. There was no evidence of goblet cell disappearance due to ammonia treatment. In the second experiment, four broilers were randomly allocated to each of four chambers and exposed to 0, 50, 75, or 100 ppm NH3 for 4 days. There was an increase in the thickness of the atrial walls and a shrinking of air capillaries with increasing NH3 concentration; in birds exposed to 75 and 100 ppm NH3, wall thickness was one to two times greater than in the control birds. There were no observable differences in gross appearance of lungs and tracheas between control and exposed groups except for hemorrhagic spots on one of the lungs exposed to 100 ppm NH3.