title: Morphological Pulmonary Diffusion Capacity for Oxygen of Burmese Pythons (Python molurus): a Comparison of Animals in Healthy Condition and with Different Pulmonary Infections.
abstract: A qualitative and quantitative morphological study of the pulmonary exchange capacity of healthy and diseased Burmese pythons (Python molurus) was carried out in order to test the hypothesis that the high morphological excess capacity for oxygen exchange in the lungs of these snakes is one of the reasons why pathological processes extend throughout the lung parenchyma and impair major parts of the lungs before clinical signs of respiratory disease become apparent. Twenty-four Burmese pythons (12 healthy and 12 diseased) were included in the study. A stereology-based approach was used to quantify the lung parenchyma using computed tomography. Light microscopy was used to quantify tissue compartments and the respiratory exchange surface, and transmission electron microscopy was used to measure the thickness of the diffusion barrier. The morphological diffusion capacity for oxygen of the lungs and the anatomical diffusion factor were calculated. The calculated anatomical diffusion capacity was compared with published values for oxygen consumption of healthy snakes, and the degree to which the exchange capacity can be obstructed before normal physiological function is impaired was estimated. Heterogeneous pulmonary infections result in graded morphological transformations of pulmonary parenchyma involving lymphocyte migration into the connective tissue and thickening of the septal connective tissue, increasing thickness of the diffusion barrier and increasing transformation of the pulmonary epithelium into a columnar pseudostratified or stratified epithelium. The transformed epithelium developed by hyperplasia of ciliated cells arising from the tip of the faveolar septa and by hyperplasia of type II pneumocytes. These results support the idea that the lungs have a remarkable overcapacity for oxygen consumption and that the development of pulmonary disease continuously reduces the capacity for oxygen consumption. However, due to the overcapacity of the lungs, this reduction does not result in clinical signs and disease can progress unrecognized for an extended period.
authors.affiliation: Department of Biology II, Biocentre, University of Munich (LMU), Großhadernerstr. 2, Planegg-Martinsried, Leipzig, Germany.
authors.forename: J M
authors.initials: JM
authors.lastname: Starck
authors.affiliation: Department of Biology II, Biocentre, University of Munich (LMU), Großhadernerstr. 2, Planegg-Martinsried, Leipzig, Germany.
authors.forename: I
authors.initials: I
authors.lastname: Weimer
authors.affiliation: Laboklin GmbH & Co. KG, Steubenstr. 4, Bad Kissingen, Leipzig, Germany.
authors.forename: H
authors.initials: H
authors.lastname: Aupperle
authors.affiliation: Department of Biology II, Biocentre, University of Munich (LMU), Großhadernerstr. 2, Planegg-Martinsried, Leipzig, Germany.
authors.forename: K
authors.initials: K
authors.lastname: Müller
authors.affiliation: Clinic for Birds and Reptiles, University of Leipzig, An den Tierkliniken 17, Leipzig, Germany.
authors.forename: R E
authors.initials: RE
authors.lastname: Marschang
authors.affiliation: Department of Small Animal Medicine, University of Leipzig, An den Tierkliniken 23, Leipzig, Germany.
authors.forename: I
authors.initials: I
authors.lastname: Kiefer
authors.affiliation: Laboklin GmbH & Co. KG, Steubenstr. 4, Bad Kissingen, Leipzig, Germany. Electronic address: pees@vogelklinik.uni-leipzig.de.
authors.forename: M
authors.initials: M
authors.lastname: Pees
mesh_terms: D000818:Animals; D017821:Boidae / Q000502:physiology*; D011659:Pulmonary Gas Exchange / Q000502:physiology*; D012141:Respiratory Tract Infections / Q000503:physiopathology / Q000662:veterinary*
keywords: lung parenchyma; morphometry; oxygen exchange capacity; snake