| Structural and functional development of the respiratory system in a newborn marsupial with cutaneous gas exchange. | |
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MedLine Citation:
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PMID: 22030856 Owner: NLM Status: In-Data-Review |
Abstract/OtherAbstract:
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Abstract Marsupials are born with structurally immature lungs and rely, to varying degrees, on cutaneous gas exchange. With a gestation of 13 d and a birth weight of 13 mg, the fat-tailed dunnart (Sminthopsis crassicaudata) is one of the smallest and most immature marsupial newborns. We determined that the skin is almost solely responsible for gas exchange in the early neonatal period. Indeed, fewer than 35% of newborn dunnarts were observed to make any respiratory effort on the day of birth, with pulmonary ventilation alone not meeting the demand for oxygen until approximately 35 d postpartum. Despite the lack of pulmonary ventilation, the phrenic nerve had made contact with the diaphragm, and the respiratory epithelium was sufficiently developed to support gas exchange on the day of birth. Both type I and type II (surfactant-producing) alveolar epithelial cells were present, with fewer than 7% of the cells resembling undifferentiated alveolar epithelial precursor cells. The type I epithelial cells did, however, display thickened cytoplasmic extensions, leading to a high diffusion distance for oxygen. In addition, the architecture of the lung was immature, resembling the early canalicular stage, with alveolarization not commencing until 45 d postpartum. The pulmonary vasculature was also immature, with a centrally positioned single-capillary layer not evident until 100 d postbirth. These structural limitations may impede efficient pulmonary gas exchange, forcing the neonatal fat-tailed dunnart to rely predominately on its skin, a phenomenon supported by a low metabolic rate and small size. |
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Authors:
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Shannon J Simpson; Sharon J Flecknoe; Robin D Clugston; John J Greer; Stuart B Hooper; Peter B Frappell |
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Publication Detail:
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Type: Journal Article Date: 2011-10-14 |
Journal Detail:
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Title: Physiological and biochemical zoology : PBZ Volume: 84 ISSN: 1537-5293 ISO Abbreviation: Physiol. Biochem. Zool. Publication Date: 2011 Nov |
Date Detail:
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Created Date: 2011-10-27 Completed Date: - Revised Date: - |
Medline Journal Info:
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Nlm Unique ID: 100883369 Medline TA: Physiol Biochem Zool Country: United States |
Other Details:
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Languages: eng Pagination: 634-49 Citation Subset: IM |
Affiliation:
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Adaptational and Evolutionary Respiratory Physiology Laboratory, School of Zoology, University of Tasmania, Hobart, Tasmania 7005, Australia; 2Department of Physiology, Monash University, Victoria 3800, Australia; 3Centre for Neuroscience, Department of Physiology, University of Alberta, Edmonton, Alberta T6G 2E1, Canada. |
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From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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