Bronchial circulation in the marsupial opossum, Didelphis marsupialis.
This study characterizes the existence of a bronchial circulation in a marsupial, an animal which does not undergo placental development and does not have a ductus arteriosus. Direct perfusion of the lung by the pulmonary vasculature during the fetal development of opossums may occur, potentially eliminating the need for a bronchial circulation. We used radio- and fluorescent-labeled microspheres in conjunction with postmortem intravascular casting to determine if opossums have a systemic (bronchial) blood supply to the lung (n = 9). Gross postmortem examination of the intravascular casts showed a well-developed common bronchial artery. The histological distribution pattern of fluorescent microspheres was primarily to the airways. A few fluorescent microspheres were observed in the alveolar capillaries, indicating that a precapillary bronchial-to-pulmonary anastomosis exists in the opossum. Using the reference flow technique, total bronchial blood flow to the left lung averaged 0.95 +/- 0.58 SE ml/min. The presence of a bronchial circulation in the opossum suggests that it is more than a vestigial structure from embryonic development, potentially supporting its functional importance for carrying nutrients to the airway.
Department of Pulmonary and Critical Care Medicine, University of Washington School of Medicine, Seattle, USA. susan@colossus.pulmcc.washington.edu
S L
SL
Bernard
D L
DL
Luchtel
R W
RW
Glenny
S
S
Lakshminarayan
D000818:Animals; D001775:Blood Circulation / Q000502:physiology; D001794:Blood Pressure; D001981:Bronchial Arteries / Q000033:anatomy & histology; D005456:Fluorescent Dyes; D008168:Lung / Q000033:anatomy & histology / Q000098:blood supply* / Q000254:growth & development; D008394:Marsupialia / Q000502:physiology; D008853:Microscopy; D008863:Microspheres; D009893:Opossums / Q000502:physiology*; D011652:Pulmonary Circulation / Q000502:physiology*
D005456:Fluorescent Dyes