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Structural and Functional Development of the Respiratory System in a Newborn Marsupial with Cutaneous Gas Exchange
Citation
Simpson, SJ and Flecknoe, SJ and Clugston, RD and Greer, JJ and Hooper, SB and Frappell, PB, Structural and Functional Development of the Respiratory System in a Newborn Marsupial with Cutaneous Gas Exchange, Physiological and Biochemical Zoology, 84, (6) pp. 634-649. ISSN 1522-2152 (2011) [Refereed Article]
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Copyright Statement
© 2011 by The University of Chicago
DOI: doi:10.1086/662557
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 neo-
natal 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 de-
mand 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 cy-
toplasmic 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 vascula-
ture was also immature, with a centrally positioned single-
capillary layer not evident until 100 d postbirth. These struc-
tural limitations may impede efficient pulmonary gas exchange,
forcing the neonatal fat-tailed dunnart to rely predominatelyon its skin, a phenomenon supported by a low metabolic rate
and small size.
Item Details
Item Type: | Refereed Article |
---|---|
Research Division: | Biological Sciences |
Research Group: | Biochemistry and cell biology |
Research Field: | Structural biology (incl. macromolecular modelling) |
Objective Division: | Environmental Management |
Objective Group: | Management of Antarctic and Southern Ocean environments |
Objective Field: | Assessment and management of Antarctic and Southern Ocean ecosystems |
UTAS Author: | Simpson, SJ (Ms Shannon Simpson) |
UTAS Author: | Frappell, PB (Professor Peter Frappell) |
ID Code: | 76092 |
Year Published: | 2011 |
Web of Science® Times Cited: | 19 |
Deposited By: | Zoology |
Deposited On: | 2012-02-27 |
Last Modified: | 2017-11-01 |
Downloads: | 0 |
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