Innervation and function of the distal airways in the developing bronchial tree of fetal pig lung.

Sparrow, Malcolm; Warwick, S.P.; Everett, Alan

doi:10.1165/ajrcmb.13.5.7576686

Cited by 32 publications

(37 citation statements)

References 17 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The musculature extends from the base of the terminal endbud, comprising a layer of newly differentiated cells, to the proximal trachea (10,25,26). It maintains this cylindrical arrangement around the airways from the early pseudoglandular stage to postnatal life, except in the trachea, where the formation of the cartilage rings later in the pseudoglandular stage reduces the muscle layer to that of a narrow segment on the dorsal side (26).…”

Section: Discussionmentioning

confidence: 99%

“…Thus, it was rarely possible to capture a complete sequence of spontaneous activity from onset to cessation. The trachea and proximal stem bronchi were generally not suitable for imaging because of the opacity of the cartilage in the wall (9,10).…”

Section: Fetal Pigsmentioning

confidence: 99%

“…They were numbered L1 to L5 on each bronchus, with L1 arising from the trachea on the right-hand side. The structures of the bronchial trees of 8-and 20-g fetal pig lungs have been depicted earlier (9,10), where the diameters of the stem bronchi, laterals and their secondary and tertiary branches are given. The stages of lung development in both the pig and the rabbit were determined from hematoxylin and eosin-stained paraffin sections, 5 m thick, according to the criteria of Burri and Moschopulos (18).…”

Section: Nomenclature Of the Airways And Assessment Of Lung-developmementioning

confidence: 99%

“…McCray (7) noted spontaneous activity of epithelial tubules in small fragments of fresh lungs from first-trimester human fetuses and characterized their contractile responses to pharmacologic agents (discussed later). Sparrow and colleagues (9,10) video-recorded sequences of strong spontaneous narrowing of individual airways in the isolated intact bronchial tree in the late first and early second trimesters of fetal pig lung. The spontaneous narrowing moved the lung liquid backward and forward along the airway lumen.…”

mentioning

confidence: 99%

“…The airways also contracted strongly to many agonists, e.g., acetylcholine (ACh), histamine, and Substance P, displaying a force per cross-sectional area of smooth muscle and a sensitivity comparable with that of the airways of postnatal animals (9-11). They relax with ␤ -agonists in explants (7) and throughout the airways of the freshly isolated fetal bronchial tree (9,10). The spontaneous activity is unaffected by tetrodoxin, indicating that neural activity is not essential, and by atropine, showing that endogenous ACh is not involved.…”

mentioning

confidence: 99%

See 4 more Smart Citations

Spontaneous Peristaltic Airway Contractions Propel Lung Liquid through the Bronchial Tree of Intact and Fetal Lung Explants

Schittny

Miserocchi

Sparrow

2000

Am J Respir Cell Mol Biol

145

110

View full text Add to dashboard Cite

Spontaneous contractions of the fetal airways are a well recognized but poorly characterized phenomenon. In the present study spontaneous narrowing of the airways was analyzed in freshly isolated lungs from early to late gestation in fetal pigs and rabbits and in cultured fetal mouse lungs. Propagating waves of contraction traveling proximal to distal were observed in fresh lungs throughout gestation which displaced the lung liquid along the lumen. In the pseudoglandular and canalicular stages (fetal pigs) the frequency ranged from 2.3 to 3.3 contractions/min with a 39 to 46% maximum reduction of lumen diameter. In the saccular stage (rabbit) the frequency was 10 to 12/min with a narrowing of ‫ف‬ 30%. In the organ cultures the waves of narrowing started at the trachea in whole lungs, or at the main bronchus in lobes (5.2 Ϯ 1.5 contractions/min, 22 Ϯ 8% reduction of lumen diameter), and as they proceeded distally along the epithelial tubes the luminal liquid was shifted toward the terminal tubules, which expanded the endbuds. Spontaneous narrowing and relaxation of the airways in the developing fetal lung has been described since the early part of the twentieth century. These spontaneous contractions are characteristic of phasic smooth muscle where regular bursts of action potentials give rise to rhythmic mechanical activity, typified by the smooth muscle of the viscera (1). Yet the contraction of mammalian airway smooth muscle in postnatal life is characterized by slow, graded contractions leading to airway narrowing and occurs without the generation of action potentials during membrane depolarization (2, 3). This is classified as tonic smooth muscle, in common with many blood vessels (1). Perhaps the rhythmic contractile activity of fetal airway smooth muscle is not so surprising since the intestine and the lung have a common embryological origin, with the lung developing as an outgrowth of the foregut in the late embryonic stage (4). Nevertheless, it indicates that airway smooth muscle would need to lose its capacity to generate spontaneous electrical activity sometime during fetal life or at birth and acquire the characteristics of tonic smooth muscle. If and when this occurs is unknown.The phenomenon of spontaneous narrowing of airways in the fetal lung was first observed in explants of lung in culture from embryos of chicken (5) and guinea pigs (6). More recently it was reported in explants of first-trimester human lung (7) and in gestation Day 11 mouse lung (8), where by 48 h in culture, spontaneous contractions began. However, much less information is available for intact fetal airways. McCray (7) noted spontaneous activity of epithelial tubules in small fragments of fresh lungs from first-trimester human fetuses and characterized their contractile responses to pharmacologic agents (discussed later). Sparrow and colleagues (9, 10) video-recorded sequences of strong spontaneous narrowing of individual airways in the isolated intact bronchial tree in the late first and early second trimesters of fetal pig l...

show abstract

Section: Discussionmentioning

confidence: 99%

Section: Fetal Pigsmentioning

confidence: 99%

Section: Nomenclature Of the Airways And Assessment Of Lung-developmementioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

See 3 more Smart Citations

Spontaneous Peristaltic Airway Contractions Propel Lung Liquid through the Bronchial Tree of Intact and Fetal Lung Explants

Schittny

Miserocchi

Sparrow

2000

Am J Respir Cell Mol Biol

145

110

View full text Add to dashboard Cite

show abstract

Spatial and temporal distribution of nerves, ganglia, and smooth muscle during the early pseudoglandular stage of fetal mouse lung development

Tollet

Everett

Sparrow

2001

Developmental Dynamics

View full text Add to dashboard Cite

Neural tissue and smooth muscle appear early in the developing fetal lung, but little is known of their origin and subsequent distribution. To investigate the spatial and temporal distribution of nerves, ganglia, and airway smooth muscle during the early pseudoglandular stage, fetal mouse lungs at embryonic days (E) 11 to 14 were immunostained as whole-mounts and imaged by confocal microscopy. At E11, the primordial lung consisted of the future trachea and two budding epithelial tubules that were covered in smooth muscle to the base of the growing buds. The vagus and processes entering the lung were positive for the neural markers PGP 9.5 (protein gene product 9.5) and synapsin but no neurons were stained at this stage. An antibody to p75 NTR revealed neural crest cells on the future trachea as well as in the vagus and in processes extending from the vagus to the lung. This finding indicates that even though neuronal precursors are already present at this stage, they are still migrating into the lung. By E12, neural tissue was abundant in the proximal part of the lung and nerves followed the smooth muscle-covered tubules to the base of the growing buds. At E13 and E14, a neural network of interconnected ganglia, innervated by the vagus, covered the trachea. The postganglionic nerves mainly followed the smooth muscle-covered tubules, but some extended out into the mesenchyme beyond the epithelial buds. Furthermore, we show in a model of cultured lung explants that neural tissue and smooth muscle persist and continue to grow and differentiate in vitro. By using fluorescent markers and confocal microscopy, we present the developing lung as a dynamic structure with smooth muscle and neural tissue in a prime position to influence growth and development.

show abstract

Correlation of tracheal smooth muscle function with structure and protein expression during early development

Cullen

Cooke

Driska

et al. 2007

Pediatric Pulmonology

View full text Add to dashboard Cite

With increased survival of premature infants, understanding the impact of development on airway function and structure is imperative. Airway smooth muscle plays a primary role in the modulation of airway function. The purpose of this study is to correlate the functional maturation of airway smooth muscle during the perinatal period with structural alterations at the cellular, ultrastructural, and molecular levels. Length-tension and dose-response analyses were performed on tracheal rings acquired from preterm and term newborn lambs. Subsequent structural analyses included isolated airway smooth muscle cell length, electron microscopy, and myosin heavy chain isoform expression measurements. Functionally the compliance, contractility, and agonist sensitivity of the tracheal rings matured during preterm to term development. Structurally, isolated cell lengths and electron microscopic ultrastructure were not significantly altered during perinatal development. However, expression of myosin heavy chain isoforms increased significantly across the age range analyzed, correlating with the maturational increase in smooth muscle contractility. In conclusion, the developmental alterations in tracheal function appear due, in part, to enhanced smooth muscle myosin heavy chain expression.

show abstract

Innervation and function of the distal airways in the developing bronchial tree of fetal pig lung.

Cited by 32 publications

References 17 publications

Spontaneous Peristaltic Airway Contractions Propel Lung Liquid through the Bronchial Tree of Intact and Fetal Lung Explants

Spontaneous Peristaltic Airway Contractions Propel Lung Liquid through the Bronchial Tree of Intact and Fetal Lung Explants

Spatial and temporal distribution of nerves, ganglia, and smooth muscle during the early pseudoglandular stage of fetal mouse lung development

Correlation of tracheal smooth muscle function with structure and protein expression during early development

Contact Info

Product

Resources

About