title: Deposition and phagocytosis of inhaled particles in the gas exchange region of the duck, Anas platyrhynchos.
abstract: Little is known about the fate of inhaled aerosol particles in birds; even the anatomical location of phagocytic cells within the lungs has yet to be clearly demonstrated. We exposed 2 anesthetized, spontaneously breathing ducks to a non-toxic iron oxide aerosol (aerodynamic mass mean diameter = 0.18 micron; 460 mg/m3) for 1.75 h and 2 awake, resting ducks to less concentrated aerosol (38 mg/m3) for 6 h on two consecutive days. All 4 ducks were sacrificed 24 h after the end of the last exposure. Their lungs, as well as the lungs from a control duck not exposed to the aerosol, were fixed in situ by insufflation of osmium tetroxide vapor or by intravascular perfusion. Then samples of the gas exchange region were examined with a transmission electron microscope. We found iron oxide particles: trapped within the trilaminar substance that is unique to avian lungs and coats the atria and infundibula; within epithelial cells of the atria and initial portions of the infundibula; and within interstitial macrophages. Only occasionally, small amounts of particles were found in the air capillaries. We conclude that both epithelial cells and interstitial macrophages can phagocytize particles in avian lungs, and that there is some convective transport of aerosol to the atria and the initial portions of the infundibula.
mesh_terms: D000818:Animals; D004372:Ducks / Q000502:physiology*; D005260:Female; D005290:Ferric Compounds / Q000378:metabolism*; D005404:Fixatives; D006652:Histological Techniques; D008168:Lung / Q000378:metabolism*; D010587:Phagocytosis; D011659:Pulmonary Gas Exchange; D012119:Respiration
chemical_list: D005290:Ferric Compounds; D005404:Fixatives; C000499:ferric oxide