Morphometric analysis of postnatal lung development in the tammar wallaby: Light microscopy

Runciman, Sue; Baudinette, R. V.; Gannon, B. J.; Lipsett, Jill

doi:10.1016/s0034-5687(98)00034-6

Cited by 18 publications

(42 citation statements)

References 21 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The newborn marsupials measured in this study (with synchrotron imaging) show a lower than expected lung volume, until a body mass greater than 1 g, when the lungs become the main (only) source of gas exchange. Data taken from [2], [10], [31], [38], [42], [43], [45], [46], [47], [48], [49].…”

Section: Resultsmentioning

confidence: 99%

Phase Contrast Imaging Reveals Low Lung Volumes and Surface Areas in the Developing Marsupial

et al. 2013

View full text Add to dashboard Cite

Marsupials are born with immature lungs when compared to eutherian mammals and rely, to various extents, on cutaneous gas exchange in order to meet metabolic requirements. Indeed, the fat-tailed dunnart is born with lungs in the canalicular stage of development and relies almost entirely on the skin for gas exchange at birth; consequently undergoing the majority of lung development in air. Plane radiographs and computed tomography data sets were acquired using phase contrast imaging with a synchrotron radiation source for two marsupial species, the fat-tailed dunnart and the larger tammar wallaby, during the first weeks of postnatal life. Phase contrast imaging revealed that only two lung sacs contain air after the first hour of life in the fat-tailed dunnart. While the lung of the tammar wallaby was comparatively more developed, both species demonstrated massive increases in air sac number and architectural complexity during the postnatal period. In addition, both the tammar wallaby and fat-tailed dunnart had lower lung volumes and parenchymal surface areas than were expected from morphometrically determined allometric equations relating these variables to body mass during the neonatal period. However, lung volume is predicted to scale with mass as expected after the neonatal marsupial reaches a body mass of ∼1 g and no longer relies on the skin for gas exchange. Decreased lung volume in the marsupial neonate further supports the maxim that cutaneous gas exchange occurs in the marsupial neonate because the respiratory apparatus is not yet capable of meeting the gas exchange requirements of the newborn.

show abstract

Section: Resultsmentioning

confidence: 99%

Phase Contrast Imaging Reveals Low Lung Volumes and Surface Areas in the Developing Marsupial

et al. 2013

View full text Add to dashboard Cite

show abstract

“…The associated increase in metabolic rate accompanying endothermy requires an increase in the internal partitioning of the lung (Tenney and Remmers 1963) and, therefore, an increase in the number of alveoli at this time. Alveolarization in the tammar wallaby also occurs over an extended period of time with well-developed alveoli present at the time of pouch vacation (Runciman et al 1998), which corresponds to the attainment of endothermy and the associated increase in demand for oxygen and a matching increase in ventilation (Frappell 2008). The development of pulmonary circulation lags behind the development of the airways (deMello and Reid 2000;Burri 2006), and as such, the singlecapillary layer was first detected after 70 d postnatal but not centrally located until 100 d postnatal; the central location of the capillary is likely due to a thinning of the interstitium.…”

Section: Structural Development Of the Respiratory Systemmentioning

confidence: 99%

Structural and Functional Development of the Respiratory System in a Newborn Marsupial with Cutaneous Gas Exchange

Simpson¹,

Flecknoe²,

Clugston³

et al. 2011

Physiological and Biochemical Zoology

View full text Add to dashboard Cite

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.

show abstract

“…The tammar is born after a short gestation (~ 28 days) and the lungs were immature and still at the canalicular stage of development, similar to the eutherian fetal lung (Runciman et al, 1998). The majority of development occurs during early postnatal life (Frappell and MacFarlane, 2006, Saunders et al, 1989, Wang et al, 2009).…”

Section: Discussionmentioning

confidence: 99%

“…This data also correlates with morphological changes in lung observed in pouch young over this period, where the lung displays a slow rate of septal formation (Modepalli et al, 2015, Szdzuy et al, 2008). Based on the lung morphological analysis during the early postnatal life of tammar pouch young, an increase of alveolization in lung was observed from 30 days of age and which continued until 100 days (Modepalli et al, 2015, Runciman et al, 1998, Runciman et al, 1999, Szdzuy et al, 2008). In addition, from our previous studies we observed that an embryonic lung cultured in day 40 milk showed extensive branching morphogenesis and tissue growth.…”

Section: Discussionmentioning

confidence: 99%

Marsupial tammar wallaby delivers milk bioactives to altricial pouch young to support lung development

Modepalli

Hinds

Sharp

et al. 2016

Mechanisms of Development

View full text Add to dashboard Cite

Our research is exploiting the marsupial as a model to understand the signals required for lung development. Marsupials have a unique reproductive strategy, the mother gives birth to altricial neonate with an immature lung and the changes in milk composition during lactation in marsupials appears to provide bioactives that can regulate diverse aspects of lung development, including branching morphogenesis, cell proliferation and cell differentiation. These effects are seen with milk collected between 25 and 100 days postpartum. To better understand the temporal effects of milk composition on postnatal lung development we used a cross-fostering technique to restrict the tammar pouch young to milk composition not extending beyond day 25 for 45 days of its early postnatal life. These particular time points were selected as our previous study showed that milk protein collected prior to ~ day 25 had no developmental effect on mouse embryonic lungs in culture. The comparative analysis of the foster group and control young at day 45 postpartum demonstrated that foster pouch young had significantly reduced lung size. The lungs in fostered young were comprised of large intermediate tissue, had a reduced size of airway lumen and a higher percentage of parenchymal tissue. In addition, expression of marker genes for lung development (BMP4, WNT11, AQP-4, HOPX and SPB) were significantly reduced in lungs from fostered young. Further, to identify the potential bioactive expressed by mammary gland that may have developmental effect on pouch young lungs, we performed proteomics analysis on tammar milk through mass-spectrometry and listed the potential bioactives (PDGF, IGFBP5, IGFBPL1 and EGFL6) secreted in milk that may be involved in regulating pouch young lung development. The data suggest that postnatal lung development in the tammar young is most likely regulated by maternal signalling factors supplied through milk.

show abstract

Morphometric analysis of postnatal lung development in the tammar wallaby: Light microscopy

Cited by 18 publications

References 21 publications

Phase Contrast Imaging Reveals Low Lung Volumes and Surface Areas in the Developing Marsupial

Phase Contrast Imaging Reveals Low Lung Volumes and Surface Areas in the Developing Marsupial

Structural and Functional Development of the Respiratory System in a Newborn Marsupial with Cutaneous Gas Exchange

Marsupial tammar wallaby delivers milk bioactives to altricial pouch young to support lung development

Contact Info

Product

Resources

About