Avian Lung Research Articles

Mechanisms of unidirectional flow in parabronchi of avian lungs: Measurements in duck lung preparations

To investigate the pathway of respired air in birds, lungs of ducks, fixed by means of glutaraldehyde, were separated from the air sacs and from all other organs. When this isolated lung was ventilated by applying pressure or suction to the main bronchus, the dorsobronchial flow was shown to be unidirectional in both respiratory phases, leading from the mesobronchus through the dorsobronchi to the parabronchi, as has previously been shown for the living duck. Flow direction could also be measured in other parts of the bronchial tree including ventrobronchi where the measurements were not in agreement with the hypothesis of Hazelhoff (1943). To analyze the mechanisms of this rectification of flow, the aerodynamical properties of some structures of the bronchial tree, especially the openings of the secondary bronchi into the mesobronchus, were investigated. These openings offered a direction-dependent resistance to air flow, presumably due to detachment of flow at sites of sharp edges. These results lend support to the hypothesis that the particular pathway of respired air in duck lungs is effected by “aerodynamical valving”.

Afferent nerve endings in the avian lung: observations with the light microscope.

Des examens au microscope optique on montre l'existence de terminaisons nerveuses, dont on supposait la presence, dans les structures des bronchioles tertiaires et des atrium des poumons de la poule domestique (G. domesticus). Les caracteres morphologiques en sont decrits. On pense qul'il s'agit de la premiere preuve de l'existence de terminaisons afferentes dans les «conduits» d'air, realisee a l'aide du microscope optique.

Nerves in the exchange area of the avian lung.

Nerves in the exchange area of the avian lung.

Airflow dynamics in the avian lung as determined by direct and indirect methods

Intrapulmonic airflow was investigated directly using a flowmeter in the posterior dorsal secondary bronchi, and indirectly by measuring CO 2 content of airstreams passed into the trachea and out of the various air sacs. Secondary bronchial flow was found to be unidirectional in voluntary breathing but bidirectional when air was passed experimentally into and out of the trachea and air sacs. CO 2 analysis indicates that air, in the conditions of the experiment and probably also in eupnea, enters the anterior sacs, partially at least, by the tertiary bronchi and enters the posterior sacs via the direct non-exchanging connections. The role of the anterior air sacs in determining inspiratory airflow through the lung is discussed and an attempt is made at integrating the ideas of aerodynamics and lung-air-sac topology in the context of airflow in the avian lung.

How Birds Breathe

How air flows in the bird lung The finding, much against expectation, that most birds seem not to use the obvious anatomical shunt to bypass the lung when they pant, makes it even more desirable to clarify the patterns of air flow in their complex respiratory system. The respiratory system of mammals is simple; the sac-like lungs and their subdivisions are ventilated by an in-and-out flow of air with diffusion playing the major role at the terminal units, the alveoli. In the bird lung, however, there is no need for a reversal of the air flow because the finest branches of the bronchi, the parabronchi (tertiary bronchi), are open at both ends and permit through-flow of air. This characteristic, in combination with the multiplicity of tubes, branches and connections to the air-sacs, has led to a great deal of speculation as to how air flows in this complex system. Virtually all imaginable possibilities have been suggested, including some that violate physical laws, observable fact, and physiological evidence. I should therefore like to summarize the rather strong evidence we now have that air flows unidirectionally through the lung both during inhalation and exhalation, and then discuss the consequences that this has for the function of the avian lung as an efficient organ for oxygen uptake. Although bird blood has no greater affinity for oxygen than mammalian blood, the arrangement of the avian lung permits a far better utilization of oxygen than in mammals at low atmospheric pressure, which is of importance to bird flight at high altitude.

A preliminary allometric analysis of respiratory variables in resting birds

Preliminary allometric equations relating avian respiratory variables to body weight permit a series of tentative statements regarding avian respiration which were hitherto impossible. Comparisons of avian and mammalian equations reveal dimensional similarities and differences in the two distinct respiratory systems. The avian lung is similar in weight but has a proportionately smaller air space than its mammalian counterpart. The total volume of the avian respiratory system is much greater than that of mammals. Avian tidal volumes are larger than those of mammals, but avian respiratory rates are lower, and avian minute volumes are somewhat less than in comparable sized mammals. Each tidal volume in birds provides air equivalent to a complete turnover of the airspace of the lungs plus trachea. Avian respiration provides a more extensive CO 2 washout in the tertiary bronchi exchange areas than occurs in the mammalian alveoli. The amount of oxygen removed from respiratory air in birds is independent of body weight, as it is in mammals, and birds may remove a greater proportion of the oxygen than do mammals.

Analysis of gas exchange in the avian lung: Theory and experiments in the domestic fowl

Gas exchange in the parabronchial lung of birds is analysed in theory using a model suggested by Zeuthen (1942), consisting of a continuously ventilated tube, representing the parabronchi, surrounded by blood-perfused capillaries. Equations describing how partial pressures of CO 2 and O 2 in pulmonary gas and blood depend upon ventilation, perfusion and diffusing capacity are derived. The theory was applied to measurements of gas exchange in unanesthetized White Leghorn hens, of 1.6 kg average weight. In order to confine the pulmonary gas exchange to a P CO 2 and P O 2 range in which the blood dissociation curves were relatively straight, a combination of inspiratory hypoxia and hypercapnia was used ( F i CO 2 = 0.03 , F i O 2 = 0.13 ). Arterial P CO 2 was lower and arterial P O 2 was higher than the corresponding values in end-expired gas. This finding is explainable by the theory. From the experimental data the pulmonary diffusing capacity for O 2 (D LO 2 ) was estimated at 1.1 to 1.5 ml·min −1·mm Hg −1. As the calculations were based on a homogeneous lung model, these values represent a lower limit for d LO 2 .

Lung alveolar cell cytosomes: a consideration of their significance.

An ultrastructural comparison of mammalian, reptilian, and amphibian lung alveolar cells, and avian lung atrial cells reveals that morphologically similar cytoplasmic bodies (cytosomes) occur in these cells. The cytosomes, which appear generally as osmiophilic, lamellae-containing, membrane-bound, round bodies 0.3 to 0.5 μ in diameter, are also similar to bodies occurring in epithelial cells of both physoclistous and physostomatous swimbladders of fishes. Because the function of both lung alveolar and swimbladder epithelial cells is gas-handling, the possibility is raised that the morphologically similar lamellae-containing bodies of these vertebrate cells are functionally identical. One function, suggested by other investigators, is that, in mammalian lungs, these bodies supply a surface-tension lowering material (surfactant). Because several assumptions concerning this proposed function remain unproved, an alternative proposal is speculatively explored. The suggestion is offered that cytosomes contain an antioxidant needed to protect alveolar and swimbladder cells against the toxic effects of the relatively high concentration of oxygen to which these cells are exposed.

Pulmonary surfactant phospholipids from turkey lung: comparison with rabbit lung.

Pulmonary surfactant phospholipids from turkey lung: comparison with rabbit lung.

Measurements of capillary dimensions and blood volume in rapidly frozen lungs.

Measurements of capillary dimensions and blood volume in rapidly frozen lungs.

Recovery of free cells from rat lungs by repeated washings.

Recovery of free cells from rat lungs by repeated washings.

Blood and Air Volumes in the Avian Lung

HISTOLOGICAL examination of birds’ lungs indicates a considerable variation in air and blood volumes (Olander et al., 1967). However, in order to obtain quantitative estimates of these changes, methods are needed which can be applied to the entire organ. Such information is of importance in evaluating respiratory function in conditions where the lung becomes anatomically altered.Previous measurements of lung blood volumes in birds (Altman and Dittmer, 1961; McFarland, 1964) have not been made so as to prevent postmortem changes in blood volume in the organ. Other estimates of air volumes in the avian lung (King and Payne, 1958, 1962; Zeuthen, 1942) have been made by filling the respiratory tract with some foreign substance, the difficulties of which have been recognized.Consequently, new methods have been devised to measure air volumes (by buoyancy) and blood volumes (by isotope dilution) and these as well as data on normal chickens are reported .

Functional and Analytical Histochemistry of the Chicken Lung Lobule with Particular Reference to Surfactant

THOUGH the avian lung has been studied for many years (Campana, 1875; Fisher, 1905; Locy and Larsell, 1916 a, b; Akester, 1960), the relationship of structure to function is still incompletely understood (Vos, 1934; Dotterweich, 1936; Hazelhoff, 1951; Biggs and King, 1957; Shepard et al., 1959). The presence and possible role of a pulmonary surfactant in avian lungs is contested (Miller and Bondurant, 1961; Pattle, 1963). Electron microscopy has revealed osmiophilic inclusions in the epithelium of tertiary bronchi and atria (Nagaishi et al., 1964; Tyler and Pangborn, 1964), and a unique laminated membrane surface of these epithelial cells (Tyler and Pangborn, 1964). Similar inclusions in the alveolar epithelium of mammals are thought to be the source of the pulmonary surfactant (Klaus et al., 1962).Histochemical methods, although mainly qualitative, permit precise localization of chemical activities among the various tissue components of an organ. This type of information is not obtainable …

Reaction of the chick to one atmosphere of oxygen

The white Leghorn chick between the ages of 2 and 7 weeks is markedly resistant to the toxic effects of 1 atm O2. Continuous exposure for as long as 4 weeks caused neither deaths, obvious morbidity, or signs of pulmonary damage on gross autopsy. Nevertheless the hyperoxia had some adverse effects, primarily reducing the growth rate to 75–25% of normal, reducing feed intake per unit body weight to 75% of normal, slowing respiratory rate by 31%, decreasing erythrocytes, hemoglobin, and hematocrit by 9– 12%, and causing some reversible histological changes in the lungs. Arterial O2 tensions were elevated over 300 mm Hg, but arterial Pco2 and blood pH were unaffected. No residual effects were noted upon return to air breathing. The anatomical peculiarities of the avian lung may play some role in the chicks resistance to hyperoxia, but it is also possible that it is a function of age similar to the tolerance shown by the young rat but not the adult. oxygen toxicity; chick respiratory system; artificial atmospheres; avian physiology; sealed systems Submitted on February 8, 1965

Functional Design of the Tracheal System of Flying Insects as Compared with the Avian Lung

ABSTRACT A process as demanding in power as that of flapping flight influences most physiological systems very greatly and above all the respiratory system. In the thorax of adult winged insects, it has become so intricate and integrated by fusion and extension that it is difficult to describe in comparative or in functional terms. In fact, because of lack of knowledge about the functional morphology little is known about the supply of oxygen to the wing muscles and the exchange of respiratory gases between the thorax and the ambient air.

LAMINATED MEMBRANE SURFACE AND OSMIOPHILIC INCLUSIONS IN AVIAN LUNG EPITHELIUM.

A study of the fine structure of the avian lung revealed the presence of a unique laminated membrane surface and associated osmiophilic inclusions in epithelial cells of the tertiary bronchi and atria. These structures were not found in the air-capillary epithelium. Each lamination of the membrane surface had the appearance and dimensions of the unit membrane. It is suggested that the laminated membrane surface is associated with the formation of the osmiophilic inclusions and that these inclusions compare with those described in mammalian alveolar epithelium. It is further suggested that the laminated membrane surface is lipoprotein or phospholipid in composition and is responsible for the surface-tension-reducing properties of avian lung extracts.

The influence of age and environmental factors on the behaviour of reaggregated embryonic lung cells in culture

1. 1. The developmental histology of the avian embryonic lung has been briefly described; the lung rudiment progresses from a simple structure of epithelial tubes imbedded in mesenchyme at 7 days of age, to a complicated network of tubes, interlacing air capillaries, blood vessels and smooth muscle at 18 days. 2. 2. Embryonic lungs aged 7 to 18 days have been dissociated and reaggregated in a reproducible manner; reaggregation is excellent from 7 to 12 days, but progressively declines with advancing age. The optimum period for complex histotypical reorganization within reaggregates is from 11 to 12 days. Before this time, reorganization is relatively simple while the ability of cells older than 12 days to reconstruct typical structures progressively declines. 3. 3. Isolated pure epithelial cells from 12-day lung fail to reorganize typical structures during 48 hr in culture, but have their full histogenetic capacity when mixed with an optimal proportion of mesenchymal cells at the time of culture. These observations stress the importance of epithelial-mesenchymal interactions in histogenesis, which are thought to be examples of complex histological self-organization rather than of inductive interactions. 4. 4. Pure epithelial cells in culture retain their competency to react with mesenchymal cells for periods of up to 19 hr. This indicates that under the conditions of culture there is no temporal alteration in the capabilities of these cells to interact. 5. 5. Biochemical studies of freshly dissociated 12-day lung cells show that glycolytic enzyme systems are unimpared. About one-third of the cytoplasmic RNA is extracted by the dissociation process, but is resynthesized in culture within 24 hr. 6. 6. The implications of these observations in terms of reconstructive histogenesis in culture has been discussed.

Artificial Respiration in Birds by Unidirectional Air Flow

Depression of respiratory movements by anesthesia is a frequent cause of bird death during surgery; however, asphyxia so caused may often be prevented by artificial respiration. With birds the technique described herein is very simple, and involves none of the elaborate equipment required for artificial respiration in mammals.The avian lung parenchyma consists of a series of interconnecting tubules that lead untimately into air sacs. The normal flow of air in the lungs (regardless of controversial theories of air-flow mechanisms) is through these tubules, to and/or from at least some of the air sacs. If access to an air sac is established, a unidirectional air flow that maintains fully adequate respiratory exchange may be established in either direction.This technique has been used for several years in our laboratory (e.g., VanMatre, 1957; Lytle, 1958) for routine surgery, and also for class exercises in respiratory physiology. The post-thoracic air sac is…

A new experimental approach to the problem of the air pathway withing the avian lung.

The Journal of PhysiologyVolume 138, Issue 2 p. 282-299 ArticleFree Access New experimental approach to the problem of the air pathway within the avian lung P. M. Biggs, P. M. BiggsSearch for more papers by this authorA. S. King, A. S. KingSearch for more papers by this author P. M. Biggs, P. M. BiggsSearch for more papers by this authorA. S. King, A. S. KingSearch for more papers by this author First published: 23 September 1957 https://doi.org/10.1113/jphysiol.1957.sp005851Citations: 20AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat Citing Literature Volume138, Issue2September 23, 1957Pages 282-299 RelatedInformation

Temperature and Host Cell Factors in the Growth of Influenza Virus (PR8 Strain) in Avian Tissues in Vitro

Summary This study demonstrates that with PR8 strain of influenza A virus in tissue cultures of avian embryonic lung, raising the temperature of incubation from 37 to 41°C does not prevent virus multiplication. In contrast to embryonic lung tissue, lung tissue from 2-day hatched chicks gives no clear-cut evidence of virus under any of the conditions studied. Using embryonic tissues, PR8 virus multiplication, as evidenced by a rise in egg infectivity titer, is greatest with lung and chorioallantoic membrane tissue, less marked with skin-muscle, gut and liver tissue, and not detectable in the case of heart tissue. The maturation of tissues from the embryonic stage to that of the 2-day hatched chick is associated with the loss of capacity to support PR8 virus multiplication. This difference in tissue susceptibility does not appear to be due to alteration of the environmental temperature of the cells from that of the embryo (37°C) to that of the hatched chick (41°C).