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Maina JN. A critical assessment of the cellular defences of the avian respiratory system: are birds in general and poultry in particular relatively more susceptible to pulmonary infections/afflictions? Biol Rev Camb Philos Soc 2023; 98:2152-2187. [PMID: 37489059 DOI: 10.1111/brv.13000] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2023] [Revised: 07/01/2023] [Accepted: 07/07/2023] [Indexed: 07/26/2023]
Abstract
In commercial poultry farming, respiratory diseases cause high morbidities and mortalities, begetting colossal economic losses. Without empirical evidence, early observations led to the supposition that birds in general, and poultry in particular, have weak innate and adaptive pulmonary defences and are therefore highly susceptible to injury by pathogens. Recent findings have, however, shown that birds possess notably efficient pulmonary defences that include: (i) a structurally complex three-tiered airway arrangement with aerodynamically intricate air-flow dynamics that provide efficient filtration of inhaled air; (ii) a specialised airway mucosal lining that comprises air-filtering (ciliated) cells and various resident phagocytic cells such as surface and tissue macrophages, dendritic cells and lymphocytes; (iii) an exceptionally efficient mucociliary escalator system that efficiently removes trapped foreign agents; (iv) phagocytotic atrial and infundibular epithelial cells; (v) phagocytically competent surface macrophages that destroy pathogens and injurious particulates; (vi) pulmonary intravascular macrophages that protect the lung from the vascular side; and (vii) proficiently phagocytic pulmonary extravasated erythrocytes. Additionally, the avian respiratory system rapidly translocates phagocytic cells onto the respiratory surface, ostensibly from the subepithelial space and the circulatory system: the mobilised cells complement the surface macrophages in destroying foreign agents. Further studies are needed to determine whether the posited weak defence of the avian respiratory system is a global avian feature or is exclusive to poultry. This review argues that any inadequacies of pulmonary defences in poultry may have derived from exacting genetic manipulation(s) for traits such as rapid weight gain from efficient conversion of food into meat and eggs and the harsh environmental conditions and severe husbandry operations in modern poultry farming. To reduce pulmonary diseases and their severity, greater effort must be directed at establishment of optimal poultry housing conditions and use of more humane husbandry practices.
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Affiliation(s)
- John N Maina
- Department of Zoology, University of Johannesburg, Auckland Park Campus, Kingsway Avenue, Johannesburg, 2006, South Africa
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Maina JN. Perspectives on the Structure and Function of the Avian Respiratory System: Functional Efficiency Built on Structural Complexity. FRONTIERS IN ANIMAL SCIENCE 2022. [DOI: 10.3389/fanim.2022.851574] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Among the air-breathing vertebrates, regarding respiratory efficiency, the avian respiratory system rests at the evolutionary zenith. Structurally, it is separated into a lung that serves as a gas exchanger and air sacs that mechanically ventilate the lung continuously and unidirectionally in a caudocranial direction. Largely avascular, the air sacs are delicate, transparent, compliant and capacious air-filled spaces that are not meaningfully involved in gas exchange. The avian lungs are deeply and firmly attached to the vertebrae and the ribs on the dorsolateral aspects, rendering them practically rigid and inflexible. The attachment of the lung to the body wall allowed extreme subdivision of the exchange tissue into minuscule and stable terminal respiratory units, the air capillaries. The process generated a large respiratory surface area in small lungs with low volume density of gas exchange tissue. For the respiratory structures, invariably, thin blood-gas barrier, large respiratory surface area and large pulmonary capillary blood volume are the foremost adaptive structural features that confer large total pulmonary morphometric diffusing capacities of O2. At parabronchial level, the construction and the arrangement of the airway- and the vascular components of the avian lung determine the delivery, the presentation and the exposure of inspired air to capillary blood across the blood-gas barrier. In the avian lung, crosscurrent-, countercurrent- and multicapillary serial arterialization systems that stem from the organization of the structural parts of the lung promote gas exchange. The exceptional respiratory efficiency of the avian respiratory system stems from synergy of morphological properties and physiological processes, means by which O2 uptake is optimized and high metabolic states and capacities supported. Given that among the extant animal taxa insects, birds and bats (which accomplished volancy chronologically in that order) possess structurally much different respiratory systems, the avian respiratory system was by no means a prerequisite for evolution of powered flight but was but one of the adaptive solutions to realization of an exceptionally efficient mode of locomotion.
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Kandyel RM, El Basyouny HA, El Nahas EE, Madkour F, Haddad S, Massoud D, Morsy K, Madkour N, Abumandour M. A histological and immunohistochemical study on the parabronchial epithelium of the domestic fowl's (Gallus gallus domesticus) lung with special reference to its scanning and transmission electron microscopic characteristics. Microsc Res Tech 2021; 85:1108-1119. [PMID: 34761477 DOI: 10.1002/jemt.23980] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2021] [Revised: 10/02/2021] [Accepted: 10/28/2021] [Indexed: 11/07/2022]
Abstract
The current study was designed to give complete histo-and immunohistochemical features of the parabronchial epithelium of domestic fowl's (Gallus gallus domesticus) lung with special reference to Scanning electron microscope (SEM) and mean transmission electron microscope (TEM) features. The lung exhibited variable-sized atrial openings encircled by exchange tissue zones. The parabronchial atrial chambers appeared as ovoid and polygonal-shaped that separated by the well-developed interatrial septum. The deep atrial lumens had blood vessels pierced by openings that represent the infundibula. The parabronchial blood capillaries meshwork was branched and exhibited ovoid-shaped air capillaries with numerous extravasated blood vessels. By TEM, there were several air capillaries and groups of squamous and endothelial respiratory cells and the squamous cells had oval nucleus with evenly distributed chromatin. The endothelial respiratory cells had few microvilli on their free surfaces. The parabronchial tubes opened into a group of widened atria that had smooth muscle bundles at the interatrial septa. The atrial chambers led to narrow infundibula. Moreover, the lining epithelium of parabronchi, atria, infundibula, and air capillaries was formed by simple squamous epithelium. Air capillary walls were lined by two types of respiratory cells (Types-I and II). Collagen fibers were concentrated within the tunica externa layers of the parabronchial blood vessels as well as, they were observed in CT interparabronchial septa. Immunohistochemically, the elastin immunoreactivity was detected around the parabronchial blood vessels, at the base of each parabronchial atria, and in the area encircling the alveolar-capillary walls. Our work concluded that there are a relation between the fowl's lifestyle and the surrounding environmental conditions.
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Affiliation(s)
- Ramadan M Kandyel
- Department of Zoology, Faculty of Science, Tanta University, Tanta, Egypt
| | | | - Eman E El Nahas
- Department of Zoology, Faculty of Science, Tanta University, Tanta, Egypt
| | - Fatma Madkour
- Department of Anatomy and Embryology, Faculty of Veterinary Medicine, South Valley University, Qena, Egypt
| | - Seham Haddad
- Department of Anatomy and Embryology, Faculty of Veterinary Medicine, University of Sadat City, Sadat City, Egypt
| | - Diaa Massoud
- Department of Biology, College of Science, Jouf University, Sakaka, Al-Jouf, Saudi Arabia.,Department of Zoology, Faculty of Science, Fayoum University, Fayoum, Egypt
| | - Kareem Morsy
- Biology Department, College of Science, King Khalid University, Abha, Saudi Arabia.,Zoology Department, Faculty of Science, Cairo University, Cairo, Egypt
| | - Naglaa Madkour
- Department of Anatomy and Embryology, Faculty of Veterinary Medicine, Alexandria University, Alexandria, Egypt
| | - Mohamed Abumandour
- Department of Anatomy and Embryology, Faculty of Veterinary Medicine, Alexandria University, Alexandria, Egypt
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do Amaral-Silva L, Lambertz M, José Zara F, Klein W, Gargaglioni LH, Bícego KC. Parabronchial remodeling in chicks in response to embryonic hypoxia. ACTA ACUST UNITED AC 2019; 222:jeb.197970. [PMID: 31028104 DOI: 10.1242/jeb.197970] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2018] [Accepted: 04/18/2019] [Indexed: 01/31/2023]
Abstract
The embryonic development of parabronchi occurs mainly during the second half of incubation in precocious birds, which makes this phase sensitive to possible morphological modifications induced by O2 supply limitation. Thus, we hypothesized that hypoxia during the embryonic phase of parabronchial development induces morphological changes that remain after hatching. To test this hypothesis, chicken embryos were incubated entirely (21 days) under normoxia or partially under hypoxia (15% O2 during days 12 to 18). Lung structures, including air capillaries, blood capillaries, infundibula, atria, parabronchial lumen, bronchi, blood vessels larger than capillaries and interparabronchial tissue, in 1- and 10-day-old chicks were analyzed using light microscopy-assisted stereology. Tissue barrier and surface area of air capillaries were measured using electron microscopy-assisted stereology, allowing for calculation of the anatomical diffusion factor. Hypoxia increased the relative volumes of air and blood capillaries, structures directly involved in gas exchange, but decreased the relative volumes of atria in both groups of chicks, and the parabronchial lumen in older chicks. Accordingly, the surface area of the air capillaries and the anatomical diffusion factor were increased under hypoxic incubation. Treatment did not alter total lung volume, relative volumes of infundibula, bronchi, blood vessels larger than capillaries, interparabronchial tissue or the tissue barrier of any group. We conclude that hypoxia during the embryonic phase of parabronchial development leads to a morphological remodeling, characterized by increased volume density and respiratory surface area of structures involved in gas exchange at the expense of structures responsible for air conduction in chicks up to 10 days old.
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Affiliation(s)
- Lara do Amaral-Silva
- Department of Animal Morphology and Physiology, College of Agricultural and Veterinary Sciences, São Paulo State University, Unesp. Jaboticabal, São Paulo 14884-900, Brazil.,National Institute of Science and Technology - Comparative Physiology (INCT- Fisiologia Comparada), UNESP-Jaboticabal, São Paulo 14884-900, Brazil
| | - Markus Lambertz
- Institut für Zoologie, Rheinische Friedrich-Wilhelms-Universität Bonn, 53115 Bonn, Germany.,Sektion Herpetologie, Zoologisches Forschungsmuseum Alexander Koenig, 53113 Bonn, Germany
| | - Fernando José Zara
- Invertebrate Morphology Lab, Department of Applied Biology, IEAMar and CAUNESP College of Agricultural and Veterinary Sciences, São Paulo State University, Unesp. Jaboticabal, São Paulo 14884-900, Brazil
| | - Wilfried Klein
- National Institute of Science and Technology - Comparative Physiology (INCT- Fisiologia Comparada), UNESP-Jaboticabal, São Paulo 14884-900, Brazil.,Department of Biology, School of Philosophy, Sciences and Literature of Ribeirão Preto, University of São Paulo, São Paulo 14040-901, Brazil
| | - Luciane Helena Gargaglioni
- Department of Animal Morphology and Physiology, College of Agricultural and Veterinary Sciences, São Paulo State University, Unesp. Jaboticabal, São Paulo 14884-900, Brazil.,National Institute of Science and Technology - Comparative Physiology (INCT- Fisiologia Comparada), UNESP-Jaboticabal, São Paulo 14884-900, Brazil
| | - Kênia Cardoso Bícego
- Department of Animal Morphology and Physiology, College of Agricultural and Veterinary Sciences, São Paulo State University, Unesp. Jaboticabal, São Paulo 14884-900, Brazil .,National Institute of Science and Technology - Comparative Physiology (INCT- Fisiologia Comparada), UNESP-Jaboticabal, São Paulo 14884-900, Brazil
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Wang X, O'Connor JK, Maina JN, Pan Y, Wang M, Wang Y, Zheng X, Zhou Z. Archaeorhynchus preserving significant soft tissue including probable fossilized lungs. Proc Natl Acad Sci U S A 2018; 115:11555-11560. [PMID: 30348768 PMCID: PMC6233124 DOI: 10.1073/pnas.1805803115] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
We describe a specimen of the basal ornithuromorph Archaeorhynchus spathula from the Lower Cretaceous Jiufotang Formation with extensive soft tissue preservation. Although it is the fifth specimen to be described, unlike the others it preserves significant traces of the plumage, revealing a pintail morphology previously unrecognized among Mesozoic birds, but common in extant neornithines. In addition, this specimen preserves the probable remnants of the paired lungs, an identification supported by topographical and macro- and microscopic anatomical observations. The preserved morphology reveals a lung very similar to that of living birds. It indicates that pulmonary specializations such as exceedingly subdivided parenchyma that allow birds to achieve the oxygen acquisition capacity necessary to support powered flight were present in ornithuromorph birds 120 Mya. Among extant air breathing vertebrates, birds have structurally the most complex and functionally the most efficient respiratory system, which facilitates their highly energetically demanding form of locomotion, even in extremely oxygen-poor environments. Archaeorhynchus is commonly resolved as the most basal known ornithuromorph bird, capturing a stage of avian evolution in which skeletal indicators of respiration remain primitive yet the lung microstructure appears modern. This adds to growing evidence that many physiological modifications of soft tissue systems (e.g., digestive system and respiratory system) that characterize living birds and are key to their current success may have preceded the evolution of obvious skeletal adaptations traditionally tracked through the fossil record.
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Affiliation(s)
- Xiaoli Wang
- Institute of Geology and Paleontology, Linyi University, Linyi, 276000 Shandong, China
- Shandong Tianyu Museum of Nature, Pingyi, 273300 Shandong, China
| | - Jingmai K O'Connor
- Key Laboratory of Vertebrate Evolution and Human Origins, Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences, 10010 Beijing, China;
- CAS Center for Excellence in Life and Paleoenvironment, 10010 Beijing, China
| | - John N Maina
- Department of Zoology, University of Johannesburg, 2006 Johannesburg, South Africa
| | - Yanhong Pan
- Key Laboratory of Economic Stratigraphy and Palaeogeography, Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences, 21008 Nanjing, China
| | - Min Wang
- Key Laboratory of Vertebrate Evolution and Human Origins, Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences, 10010 Beijing, China
- CAS Center for Excellence in Life and Paleoenvironment, 10010 Beijing, China
| | - Yan Wang
- Institute of Geology and Paleontology, Linyi University, Linyi, 276000 Shandong, China
- Shandong Tianyu Museum of Nature, Pingyi, 273300 Shandong, China
| | - Xiaoting Zheng
- Institute of Geology and Paleontology, Linyi University, Linyi, 276000 Shandong, China
- Shandong Tianyu Museum of Nature, Pingyi, 273300 Shandong, China
| | - Zhonghe Zhou
- Key Laboratory of Vertebrate Evolution and Human Origins, Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences, 10010 Beijing, China;
- CAS Center for Excellence in Life and Paleoenvironment, 10010 Beijing, China
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Maina JN, McCracken KG, Chua B, York JM, Milsom WK. Morphological and morphometric specializations of the lung of the Andean goose, Chloephaga melanoptera: A lifelong high-altitude resident. PLoS One 2017; 12:e0174395. [PMID: 28339478 PMCID: PMC5365123 DOI: 10.1371/journal.pone.0174395] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2017] [Accepted: 03/08/2017] [Indexed: 01/06/2023] Open
Abstract
High altitude flight in rarefied, extremely cold and hypoxic air is a very challenging activity. Only a few species of birds can achieve it. Hitherto, the structure of the lungs of such birds has not been studied. This is because of the rarity of such species and the challenges of preparing well-fixed lung tissue. Here, it was posited that in addition to the now proven physiological adaptations, high altitude flying birds will also have acquired pulmonary structural adaptations that enable them to obtain the large amounts of oxygen (O2) needed for flight at high elevation, an environment where O2 levels are very low. The Andean goose (Chloephaga melanoptera) normally resides at altitudes above 3000 meters and flies to elevations as high as 6000 meters where O2 becomes limiting. In this study, its lung was morphologically- and morphometrically investigated. It was found that structurally the lungs are exceptionally specialized for gas exchange. Atypically, the infundibulae are well-vascularized. The mass-specific volume of the lung (42.8 cm3.kg-1), the mass-specific respiratory surface area of the blood-gas (tissue) barrier (96.5 cm2.g-1) and the mass-specific volume of the pulmonary capillary blood (7.44 cm3.kg-1) were some of the highest values so far reported in birds. The pulmonary structural specializations have generated a mass-specific total (overall) pulmonary morphometric diffusing capacity of the lung for oxygen (DLo2) of 0.119 mlO2.sec-1.mbar-1.kg-1, a value that is among some of the highest ones in birds that have been studied. The adaptations of the lung of the Andean goose possibly produce the high O2 conductance needed to live and fly at high altitude.
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Affiliation(s)
- John N. Maina
- Department of Zoology, University of Johannesburg, Johannesburg, South Africa
- * E-mail:
| | - Kevin G. McCracken
- Department of Biology and Marine Biology and Ecology, Rosenstiel School of Marine and Atmospheric Sciences, University of Miami, Coral Gables, Florida, United States of America
| | - Beverly Chua
- Department of Zoology, University of British Columbia, Vancouver, Canada
| | - Julia M. York
- Department of Zoology, University of British Columbia, Vancouver, Canada
| | - William K. Milsom
- Department of Zoology, University of British Columbia, Vancouver, Canada
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Critical appraisal of some factors pertinent to the functional designs of the gas exchangers. Cell Tissue Res 2016; 367:747-767. [PMID: 27988805 DOI: 10.1007/s00441-016-2549-9] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2016] [Accepted: 11/26/2016] [Indexed: 10/20/2022]
Abstract
Respiration acquires O2 from the external fluid milieu and eliminates CO2 back into the same. Gas exchangers evolved under certain immutable physicochemical laws upon which their elemental functional design is hardwired. Adaptive changes have occurred within the constraints set by such laws to satisfy metabolic needs for O2, environmental conditions, respiratory medium utilized, lifestyle pursued and phylogenetic level of development: correlation between structure and function exists. After the inaugural simple cell membrane, as body size and structural complexity increased, respiratory organs formed by evagination or invagination: the gills developed by the former process and the lungs by the latter. Conservation of water on land was the main driver for invagination of the lungs. In gills, respiratory surface area increases by stratified arrangement of the structural components while in lungs it occurs by internal subdivision. The minuscule terminal respiratory units of lungs are stabilized by surfactant. In gas exchangers, respiratory fluid media are transported by convection over long distances, a process that requires energy. However, movement of respiratory gases across tissue barriers occurs by simple passive diffusion. Short distances and large surface areas are needed for diffusion to occur efficiently. Certain properties, e.g., diffusion of gases through the tissue barrier, stabilization of the respiratory units by surfactant and a thin tripartite tissue barrier, have been conserved during the evolution of the gas exchangers. In biology, such rare features are called Bauplans, blueprints or frozen cores. That several of them (Bauplans) exist in gas exchangers almost certainly indicates the importance of respiration to life.
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Maina JN. Pivotal debates and controversies on the structure and function of the avian respiratory system: setting the record straight. Biol Rev Camb Philos Soc 2016; 92:1475-1504. [DOI: 10.1111/brv.12292] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2015] [Revised: 06/17/2016] [Accepted: 06/27/2016] [Indexed: 12/19/2022]
Affiliation(s)
- John N. Maina
- Department of Zoology; University of Johannesburg; P.O. Box, 524, Auckland Park, Kingsway Johannesburg 2006 South Africa
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Nevitt BN, Langan JN, Adkesson MJ, Mitchell MA, Henzler M, Drees R. Comparison of air sac volume, lung volume, and lung densities determined by use of computed tomography in conscious and anesthetized Humboldt penguins (Spheniscus humboldti) positioned in ventral, dorsal, and right lateral recumbency. Am J Vet Res 2014; 75:739-45. [DOI: 10.2460/ajvr.75.8.739] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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Hsia CCW, Schmitz A, Lambertz M, Perry SF, Maina JN. Evolution of air breathing: oxygen homeostasis and the transitions from water to land and sky. Compr Physiol 2013; 3:849-915. [PMID: 23720333 PMCID: PMC3926130 DOI: 10.1002/cphy.c120003] [Citation(s) in RCA: 103] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Life originated in anoxia, but many organisms came to depend upon oxygen for survival, independently evolving diverse respiratory systems for acquiring oxygen from the environment. Ambient oxygen tension (PO2) fluctuated through the ages in correlation with biodiversity and body size, enabling organisms to migrate from water to land and air and sometimes in the opposite direction. Habitat expansion compels the use of different gas exchangers, for example, skin, gills, tracheae, lungs, and their intermediate stages, that may coexist within the same species; coexistence may be temporally disjunct (e.g., larval gills vs. adult lungs) or simultaneous (e.g., skin, gills, and lungs in some salamanders). Disparate systems exhibit similar directions of adaptation: toward larger diffusion interfaces, thinner barriers, finer dynamic regulation, and reduced cost of breathing. Efficient respiratory gas exchange, coupled to downstream convective and diffusive resistances, comprise the "oxygen cascade"-step-down of PO2 that balances supply against toxicity. Here, we review the origin of oxygen homeostasis, a primal selection factor for all respiratory systems, which in turn function as gatekeepers of the cascade. Within an organism's lifespan, the respiratory apparatus adapts in various ways to upregulate oxygen uptake in hypoxia and restrict uptake in hyperoxia. In an evolutionary context, certain species also become adapted to environmental conditions or habitual organismic demands. We, therefore, survey the comparative anatomy and physiology of respiratory systems from invertebrates to vertebrates, water to air breathers, and terrestrial to aerial inhabitants. Through the evolutionary directions and variety of gas exchangers, their shared features and individual compromises may be appreciated.
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Affiliation(s)
- Connie C W Hsia
- Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, Texas, USA.
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Maina JN, Maloiy GMO. The morphology of the respiratory organs of the African air-breathing catfish (Clarias mossambicus): A light, electron and scanning microscopic study, with morphometric observations. J Zool (1987) 2011. [DOI: 10.1111/j.1469-7998.1986.tb03602.x] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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12
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Maina JN, West JB, Orgeig S, Foot NJ, Daniels CB, Kiama SG, Gehr P, Mühlfeld C, Blank F, Müller L, Lehmann A, Brandenberger C, Rothen-Rutishauser B. Recent advances into understanding some aspects of the structure and function of mammalian and avian lungs. Physiol Biochem Zool 2010; 83:792-807. [PMID: 20687843 DOI: 10.1086/652244] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Recent findings are reported about certain aspects of the structure and function of the mammalian and avian lungs that include (a) the architecture of the air capillaries (ACs) and the blood capillaries (BCs); (b) the pulmonary blood capillary circulatory dynamics; (c) the adaptive molecular, cellular, biochemical, compositional, and developmental characteristics of the surfactant system; (d) the mechanisms of the translocation of fine and ultrafine particles across the airway epithelial barrier; and (e) the particle-cell interactions in the pulmonary airways. In the lung of the Muscovy duck Cairina moschata, at least, the ACs are rotund structures that are interconnected by narrow cylindrical sections, while the BCs comprise segments that are almost as long as they are wide. In contrast to the mammalian pulmonary BCs, which are highly compliant, those of birds practically behave like rigid tubes. Diving pressure has been a very powerful directional selection force that has influenced phenotypic changes in surfactant composition and function in lungs of marine mammals. After nanosized particulates are deposited on the respiratory tract of healthy human subjects, some reach organs such as the brain with potentially serious health implications. Finally, in the mammalian lung, dendritic cells of the pulmonary airways are powerful agents in engulfing deposited particles, and in birds, macrophages and erythrocytes are ardent phagocytizing cellular agents. The morphology of the lung that allows it to perform different functions-including gas exchange, ventilation of the lung by being compliant, defense, and secretion of important pharmacological factors-is reflected in its "compromise design."
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Affiliation(s)
- J N Maina
- Department of Zoology, University of Johannesburg, Johannesburg, South Africa.
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Malka S, Hawkins MG, Jones JH, Pascoe PJ, Kass PH, Wisner ER. Effect of body position on respiratory system volumes in anesthetized red-tailed hawks (Buteo jamaicensis) as measured via computed tomography. Am J Vet Res 2009; 70:1155-60. [DOI: 10.2460/ajvr.70.9.1155] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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14
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Makanya AN, Djonov V. Parabronchial angioarchitecture in developing and adult chickens. J Appl Physiol (1985) 2009; 106:1959-69. [PMID: 19325026 DOI: 10.1152/japplphysiol.91570.2008] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The avian lung has a highly sophisticated morphology with a complex vascular system. Extant data regarding avian pulmonary angioarchitecture are few and contradictory. We used corrosion casting techniques, light microscopy, as well as scanning and transmission electron microscopy to study the development, topography, and distribution of the parabronchial vasculature in the chicken lung. The arterial system was divisible into three hierarchical generations, all formed external to the parabronchial capillary meshwork. These included the interparabronchial arteries (A1) that ran parallel to the long axes of parabronchi and gave rise to orthogonal parabronchial arteries (A2) that formed arterioles (A3). The arterioles formed capillaries that participated in the formation of the parabronchial mantle. The venous system comprised six hierarchical generations originating from the luminal aspect of the parabronchi, where capillaries converged to form occasional tiny infundibular venules (V6) around infundibulae, or septal venules (V5) between conterminous atria. The confluence of the latter venules formed atrial veins (V4), which gave rise to intraparabronchial veins (V3) that traversed the capillary meshwork to join the interparabronchial veins (V1) directly or via parabronchial veins (V2). The primitive networks inaugurated through sprouting, migration, and fusion of vessels and the basic vascular pattern was already established by the 20th embryonic day, with the arterial system preceding the venous system. Segregation and remodeling of the fine vascular entities occurred through intussusceptive angiogenesis, a process that probably progressed well into the posthatch period. Apposition of endothelial cells to the attenuating epithelial cells of the air capillaries resulted in establishment of the thin blood-gas barrier. Fusion of blood capillaries proceeded through apposition of the anastomosing sprouts, with subsequent thinning of the abutting boundaries and ultimate communication of the lumens. Orthogonal reorientation of the blood capillaries at the air capillary level resulted in a cross-current system at the gas exchange interface.
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Affiliation(s)
- A N Makanya
- Department of Medicine, Fribourg University, CH-1700 Fribourg, Switzerland
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Maina JN. Development, structure, and function of a novel respiratory organ, the lung-air sac system of birds: to go where no other vertebrate has gone. Biol Rev Camb Philos Soc 2007. [DOI: 10.1111/j.1469-185x.2006.tb00218.x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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West JB, Watson RR, Fu Z. Major differences in the pulmonary circulation between birds and mammals. Respir Physiol Neurobiol 2006; 157:382-90. [PMID: 17222589 PMCID: PMC2681264 DOI: 10.1016/j.resp.2006.12.005] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2006] [Revised: 12/01/2006] [Accepted: 12/02/2006] [Indexed: 11/16/2022]
Abstract
The lungs of domestic chickens were perfused with blood or dextran/saline and the pulmonary artery pressure (P(a)) and venous pressure (P(v)) were varied in relation to air capillary pressure (P(A)). In Zone 3 conditions, pulmonary vascular resistance (PVR) was virtually unchanged with increases in either P(a) or P(v). This is very different behavior from mammals where the same interventions greatly reduce PVR. In Zone 2 conditions blood flow was essentially independent of P(v) as in mammalian lungs but all the capillaries appeared to be open, apparently incompatible with a Starling resistor mechanism. In Zone 1 the capillaries were open even when P(A) exceeded P(a) by over 30 cm H(2)O which is very different behavior from that of the mammalian lung. We conclude that the air capillaries that surround the blood capillaries provide rigid support in both compression and expansion of the vessels. The work suggests a pathogenesis for pulmonary hypertension syndrome in chickens which costs the broiler industry $1 billion per year.
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Affiliation(s)
- John B West
- Department of Medicine, University of California San Diego, 9500 Gilman Drive, La Jolla, CA 92093-0623, USA.
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Maina JN, West JB. Thin and strong! The bioengineering dilemma in the structural and functional design of the blood-gas barrier. Physiol Rev 2005; 85:811-44. [PMID: 15987796 DOI: 10.1152/physrev.00022.2004] [Citation(s) in RCA: 108] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
In gas exchangers, the tissue barrier, the partition that separates the respiratory media (water/air and hemolymph/blood), is exceptional for its remarkable thinness, striking strength, and vast surface area. These properties formed to meet conflicting roles: thinness was essential for efficient flux of oxygen by passive diffusion, and strength was crucial for maintaining structural integrity. What we have designated as "three-ply" or "laminated tripartite" architecture of the barrier appeared very early in the evolution of the vertebrate gas exchanger. The design is conspicuous in the water-blood barrier of the fish gills through the lungs of air-breathing vertebrates, where the plan first appeared in lungfishes (Dipnoi) some 400 million years ago. The similarity of the structural design of the barrier in respiratory organs of animals that remarkably differ phylogenetically, behaviorally, and ecologically shows that the construction has been highly conserved both vertically and horizontally, i.e., along and across the evolutionary continuum. It is conceivable that the blueprint may have been the only practical construction that could simultaneously grant satisfactory strength and promote gas exchange. In view of the very narrow allometric range of the thickness of the blood-gas barrier in the lungs of different-sized vertebrate groups, the measurement has seemingly been optimized. There is convincing, though indirect, evidence that the extracellular matrix and particularly the type IV collagen in the lamina densa of the basement membrane is the main stress-bearing component of the blood-gas barrier. Under extreme conditions of operation and in some disease states, the barrier fails with serious consequences. The lamina densa which in many parts of the blood-gas barrier is <50 nm thin is a lifeline in the true sense of the word.
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Affiliation(s)
- John N Maina
- School of Anatomical Sciences, Faculty of Health Sciences, The University of Witwatersrand, Johannesburg, South Africa
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Maina JN. Structure, function and evolution of the gas exchangers: comparative perspectives. J Anat 2002; 201:281-304. [PMID: 12430953 PMCID: PMC1570919 DOI: 10.1046/j.1469-7580.2002.00099.x] [Citation(s) in RCA: 77] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/30/2002] [Indexed: 11/20/2022] Open
Abstract
Over the evolutionary continuum, animals have faced similar fundamental challenges of acquiring molecular oxygen for aerobic metabolism. Under limitations and constraints imposed by factors such as phylogeny, behaviour, body size and environment, they have responded differently in founding optimal respiratory structures. A quintessence of the aphorism that 'necessity is the mother of invention', gas exchangers have been inaugurated through stiff cost-benefit analyses that have evoked transaction of trade-offs and compromises. Cogent structural-functional correlations occur in constructions of gas exchangers: within and between taxa, morphological complexity and respiratory efficiency increase with metabolic capacities and oxygen needs. Highly active, small endotherms have relatively better-refined gas exchangers compared with large, inactive ectotherms. Respiratory structures have developed from the plain cell membrane of the primeval prokaryotic unicells to complex multifunctional ones of the modern Metazoa. Regarding the respiratory medium used to extract oxygen from, animal life has had only two choices--water or air--within the biological range of temperature and pressure the only naturally occurring respirable fluids. In rarer cases, certain animals have adapted to using both media. Gills (evaginated gas exchangers) are the primordial respiratory organs: they are the archetypal water breathing organs. Lungs (invaginated gas exchangers) are the model air breathing organs. Bimodal (transitional) breathers occupy the water-air interface. Presentation and exposure of external (water/air) and internal (haemolymph/blood) respiratory media, features determined by geometric arrangement of the conduits, are important features for gas exchange efficiency: counter-current, cross-current, uniform pool and infinite pool designs have variably developed.
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Affiliation(s)
- J N Maina
- Department of Anatomical Sciences, The University of the Witwatersrand, Parktown, Johannesburg, South Africa.
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Maina JN. Some recent advances on the study and understanding of the functional design of the avian lung: morphological and morphometric perspectives. Biol Rev Camb Philos Soc 2002; 77:97-152. [PMID: 11911376 DOI: 10.1017/s1464793101005838] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
The small highly aerobic avian species have morphometrically superior lungs while the large flightless ones have less well-refined lungs. Two parabronchial systems, i.e. the paleopulmo and neopulmo, occur in the lungs of relatively advanced birds. Although their evolution and development are not clear, understanding their presence is physiologically important particularly since the air- and blood flow patterns in them are different. Geometrically, the bulk air flow in the parabronchial lumen, i.e. in the longitudinal direction, and the flow of deoxygenated blood from the periphery, i.e. in a centripetal direction, are perpendicularly arranged to produce a cross-current relationship. Functionally, the blood capillaries in the avian lung constitute a multicapillary serial arterialization system. The amount of oxygen and carbon dioxide exchanged arises from many modest transactions that occur where air- and blood capillaries interface along the parabronchial lengths, an additive process that greatly enhances the respiratory efficiency. In some species of birds, an epithelial tumescence occurs at the terminal part of the extrapulmonary primary bronchi (EPPB). The swelling narrows the EPPB, conceivably allowing the shunting of inspired air across the openings of the medioventral secondary bronchi, i.e. inspiratory aerodynamic valving. The defence stratagems in the avian lung differ from those of mammals: fewer surface (free) macrophages (SMs) occur, the epithelial cells that line the atria and infundibula are phagocytic, a large population of subepithelial macrophages is present and pulmonary intravascular macrophages exist. This complex defence inventory may explain the paucity of SMs in the avian lung.
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Affiliation(s)
- J N Maina
- Department of Anatomical Sciences, The Medical School, The University of the Witwatersrand, Parktown, Johannesburg, South Africa.
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Vitali SD, Richardson KC. Evaluation of pulmonary volumetric morphometry at the light and electron microscopy level in several species of passerine birds. J Anat 1998; 193 ( Pt 4):573-80. [PMID: 10029190 PMCID: PMC1467882 DOI: 10.1046/j.1469-7580.1998.19340573.x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The lungs of 3 small passerine species, having similar body mass but different diurnal activity patterns, were analysed morphometrically to assess the relationship between diurnal activity and pulmonary volumetry at the light and electron microscope levels. The percentage volumes of the major lung and exchange tissue components of the 3 species--an aerial insectivore, a foliage gleaner/nectarivore and a ground forager--were strikingly similar, and consistent with literature values for other passerine species. The only significant difference found was exchange tissue plasma volume and pulmonary haematocrit, with the ground-foraging, low activity Malurus splendens having significantly lower values than the other 2 species. This may indicate that cardiovascular parameters are more important determinants of metabolic activity in small passerines than aspects of pulmonary anatomy.
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Affiliation(s)
- S D Vitali
- Division of Veterinary and Biomedical Sciences, Murdoch University, Western Australia, Australia.
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21
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Wideman RF, Forman MF, Hughes JD, Kirby YK, Marson N, Anthony NB. Flow-dependent pulmonary vasodilation during acute unilateral pulmonary artery occlusion in Jungle Fowl. Poult Sci 1998; 77:615-26. [PMID: 9565247 DOI: 10.1093/ps/77.4.615] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Giant Jungle Fowl previously were shown to be highly resistant to the onset of pulmonary hypertension syndrome (PHS, ascites) under conditions that induce a substantial incidence of PHS in broiler chickens. In the present study, lightly anesthetized, clinically healthy 12- to 13-wk-old male Giant Jungle Fowl maintained a lower respiratory rate, a similar hematocrit, and superior arterial blood gas values when compared with 6-wk-old male broilers. Giant Jungle Fowl weighed less than broilers (1,860 +/- 19 vs 2,788 +/- 63 g, respectively) and had equivalent absolute values for pulmonary arterial pressure, cardiac output, and pulmonary vascular resistance. Acute unilateral pulmonary artery occlusion in Giant Jungle Fowl doubled the pulmonary vascular resistance and forced the right ventricle to propel a sustained 60% increase in blood flow through the vasculature of the unoccluded lung. A transient increase in pulmonary arterial pressure initially was required to overcome the vascular resistance of the unoccluded lung; however, flow-dependent vasodilation gradually reduced the pulmonary vascular resistance and permitted pulmonary arterial pressure to return toward control levels. Unilateral pulmonary artery occlusion also triggered an immediate reduction in the partial pressure of oxygen in arterial blood, and the gradual return of pulmonary arterial pressure toward control levels did not eliminate this ventilation-perfusion mismatch, which has been attributed to blood flowing too rapidly through the unoccluded lung to permit diffusive gas equilibration. The inherent capacity for flow-dependent pulmonary vasodilation may reduce the susceptibility of Giant Jungle Fowl to PHS by reducing the increment in pulmonary arterial pressure required to propel an elevated blood flow through the lungs.
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Affiliation(s)
- R F Wideman
- Department of Poultry Science, University of Arkansas, Fayetteville 72701, USA.
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The morphometry of the lung of the African lungfish (Protopterus aethiopicus) : its structural-functional correlations. ACTA ACUST UNITED AC 1997. [DOI: 10.1098/rspb.1985.0041] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
The lung of the African lungfishProtopterus aethiopicushas been investigated by morphometric techniques. The volume of the lung was strongly correlated with body mass. The exchange tissue made up about 50% of the lung. The intrapulmonary air constituted 73% of the volume of the lung, the rest being made up of the interalveolar septa (22%) and the blood capillaries (5%). The surface area of the blood-gas (tissue) barrier per unit body mass was 14.3 cm2g-1and the harmonic mean thickness of the tissue barrier 0.370 μm. The total morphometric pulmonary diffusing capacity per unit body mass was 0.0024 ml O2s-1mbar-1kg-1(1 bar = 105Pa) Of the three existing genera of lungfish, the general structure of the lung ofProtopteruswas similar to that ofLepidosirenand much unlike that ofNeoceratodus. This could be attributed to the fact that bothProtopterusandLepidosirenare obligate air-breathers whileNeoceratodusis an obligate water- breather. A comparison of the pulmonary morphometric data onProtopteruswith those of the gas exchange apparatus of other groups of vertebrates has been made and pulmonary morphometric and design specializations in the evolution of the air-breathing vertebrates from the lungfishes (some of the initial air-breathers) to reptiles through to birds are apparent.
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Comparative Pulmonary Morphology and Morphometry: The Functional Design of Respiratory Systems. ADVANCES IN COMPARATIVE AND ENVIRONMENTAL PHYSIOLOGY 1994. [DOI: 10.1007/978-3-642-78598-6_4] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
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Maina J. Morphometries of the avian lung: The structural-functional correlations in the design of the lungs of birds. ACTA ACUST UNITED AC 1993. [DOI: 10.1016/0300-9629(93)90409-w] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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King AS, Vidyadaran MK, Kassim H. Quantitative pulmonary anatomy of a ground-dwelling bird, the white-breasted water-hen (Amaurornis phoenicurus). J Zool (1987) 1992. [DOI: 10.1111/j.1469-7998.1992.tb04816.x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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Vidyadaran M, King A, Kassim H. Quantitative comparisons of lung structure of adult domestic fowl and red jungle fowl, with reference to broiler ascites. Avian Pathol 1990; 19:51-8. [DOI: 10.1080/03079459008418655] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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Lichtenbeld H, Vidić B. Effect of maternal exposure to smoke on gas diffusion capacity in neonatal rat. RESPIRATION PHYSIOLOGY 1989; 75:129-40. [PMID: 2711048 DOI: 10.1016/0034-5687(89)90058-3] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Offspring of control and experimental (chronically exposed to whole cigarette smoke) rats were sacrificed on 15th postnatal day. Pulmonary tissues were processed for quantitative electron microscopic analyses. Arithmetic and harmonic mean thicknesses were directly measured and diffusion capacity was derived for separate layers (tissue, plasma, erythrocyte) and the entire lung. Experimental offspring showed a greater volume density of interstitium in parenchyma (P less than 0.04), arithmetic (P less than 0.05) and harmonic (P less than 0.009) mean thicknesses. Diffusion capacities for lungs of both animal groups, however, were similar (0.00543 and 0.0054 cm3 O2.min-1.mm Hg-1.g body weight-1 for control and experimental lungs respectively). Experimental tissue appeared better adapted for optimal exchange of gases (P less than 0.05), as indicated by corrugation index (ratio between arithmetic and harmonic mean thicknesses) than for the control counterpart. In spite of induced alterations in several developmental processes by a presently used experimental procedure, tissue capacity for transport of gases was not significantly changed in either the alveolo-capillary membrane or the entire lung.
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Affiliation(s)
- H Lichtenbeld
- Department of Anatomy and Cell Biology, Georgetown University School of Medicine, Washington, D.C. 20007
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Maina JN. Morphology and morphometry of the normal lung of the adult vervet monkey (Cercopithecus aethiops). THE AMERICAN JOURNAL OF ANATOMY 1988; 183:258-67. [PMID: 3213831 DOI: 10.1002/aja.1001830308] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
The lungs of four adult specimens of the vervet monkey (Cercopithecus aethiops) have been examined by transmission and scanning electron microscopy. A morphometric evaluation of the structural components directly involved in gas exchange has been carried out and the data have been modelled to estimate the anatomical diffusing capacity of the lung. The upper air-conducting airways of the lung were lined by an epithelium characterized by ciliated cells among which were dispersed goblet cells. The alveolar surface was lined by squamous type I pneumocytes and cuboidal type II granular pneumocytes. The blood-gas (tissue) barrier consisted of an epithelial cell, a common basal lamina, and an endothelial cell in the thin parts of the interalveolar septum. In the thicker parts of the septum, an interstitial space interposed between the basal laminae of the epithelial and endothelial cells contained supportive elements such as collagen, elastic tissue, and fibrocytes. The alveoli, the blood capillaries, and septal tissue composed 73%, 16%, and 11%, respectively, of the parenchyma. The harmonic and arithmetic mean thicknesses of the blood-gas (tissue) barrier were 0.311 micron and 1.048 microns; the surface area of the blood-gas (tissue) barrier per unit body weight was 50 cm2g-1, and the surface density was 117 mm2.mm3-1. The weight-specific total morphometric diffusing capacity was 0.11 mlO2 (sec.mbar.kg)-1. In comparison, the pulmonary morphometric characteristics of vervet monkey lung were superior to those of the other primates (Macaca irus, M. mulatta, and Homo sapiens) for which equivalent data are available. The gas-exchange potential of the lungs of the nonhuman primates as revealed by morphometric studies surpasses that of man, a feature that can be attributed to the relatively less energetic human lifestyle.
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Affiliation(s)
- J N Maina
- Department of Veterinary Anatomy, University of Nairobi, Kenya
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Maina JN. Scanning electron microscope study of the spatial organization of the air and blood conducting components of the avian lung (Gallus gallus variant domesticus). Anat Rec (Hoboken) 1988; 222:145-53. [PMID: 3213964 DOI: 10.1002/ar.1092220206] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
The lungs of the domestic fowl were prepared for scanning electron microscopy after vascular and airway latex rubber casting to demonstrate the spatial organization of the various structural components that are involved in the gas exchange that takes place in the parabronchial tissue mantle. The bulk of the intrapulmonary air flows through the parabronchial lumen and then centrifugally diffuses into the exchange tissue through the atria, the infundibula, and the air capillaries. The blood flows centripetally from the interparabronchial arteries, then into the intraparabronchial arterioles, and finally into the blood capillaries, which together with the air capillaries constitute the functional terminal gas exchange units. The relationship between the air flow in the parabronchial lumen and the incoming blood (into the exchange tissue) has been shown to be crosscurrent, where the directions of the flow of these two gas exchange media are essentially perpendicularly disposed to each other; whereas the relationship between the blood capillaries and the air capillaries is countercurrent, the blood flowing towards the parabronchial lumen and the air in the opposite direction, i.e., towards its periphery. Both these spatial structural relationships between the air and blood are significant factors that contribute to the remarkable efficiency of the avian lung in gas exchange.(ABSTRACT TRUNCATED AT 250 WORDS)
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Affiliation(s)
- J N Maina
- Department of Veterinary Anatomy, University of Nairobi, Kenya
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Maina JN. Morphometrics of the avian lung. 4. The structural design of the charadriiform lung. RESPIRATION PHYSIOLOGY 1987; 68:99-119. [PMID: 3602614 DOI: 10.1016/0034-5687(87)90080-6] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
The lungs of five charadriiform species of bird, two of which are good divers and three predominantly flyers (soarers and gliders) have been analysed by morphometric techniques. Largely the morphometric structural values in the divers significantly exceeded those of the flyers (gulls). The average weight specific surface area of the blood-gas (tissue) barrier in the divers (28.45 +/- 2.05 cm2 X g-1 SD) surpassed that of the flyers (23.5 +/- 3.61 cm2 X g-1 SD). The divers had a higher volume of the pulmonary capillary blood per unit body weight (4.42 +/- 0.11 cm3 X kg-1 SD) than the flyers (2.84 +/- 0.58 cm3 X kg-1 SD). The weight specific volume of the lung in the divers (34.90 +/- 3.11 cm3 X kg-1 SD) exceeded that of the flyers (26.94 +/- 3.15 cm3 X kg-1 SD). The total morphometric pulmonary diffusing capacity per unit body weight in the divers (4.73 +/- 0.05 ml O2 X (min X mm Hg X kg)-1 SD) was higher than that of the flyers (3.09 +/- 0.47 ml O2 X (min X mm Hg X kg)-1 SD). The divers, however, had a notably thicker blood-gas (tissue) barrier with a harmonic mean thickness of 0.212 +/- 0.03 micron SD compared to that of the flyers (0.138 +/- 0.02 micron SD). The data acquired here commensurate the modes of life exhibited by these two groups of bird. The divers, which are relatively energetic birds, expend a lot of energy to move and stay underwater, concomitantly undergoing prolonged asphyxia during submergence and may hence need to extract as much of the oxygen in the pulmonary air as possible to prolong a dive. These birds appear in general to have structurally better adapted lungs than those of the gulls, birds which to a large extent exhibit relatively less energetic soaring and gliding flights.
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Nguyen Phu D, Yamaguchi K, Scheid P, Piiper J. Kinetics of oxygen uptake and release by red blood cells of chicken and duck. J Exp Biol 1986; 125:15-27. [PMID: 3760769 DOI: 10.1242/jeb.125.1.15] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
The specific conductance (G) for O2 transfer by red blood cells (RBCs) of chicken and muscovy duck was measured using the experimental (stopped-flow) and analytical techniques (RBC model) previously applied to human RBC (Yamaguchi, Nguyen Phu, Scheid & Piiper, 1985). Avian RBCs behaved similarly to human RBCs: G values were of similar magnitude; G for O2 uptake decreased with time and increasing O2 saturation; G for O2 release at high levels of dithionite decreased slightly with decreasing O2 saturation; G for O2 release was higher than G for O2 uptake. The deoxygenation kinetics of oxyhaemoglobin in solution was similar for both avian species. The G measured for O2 release at high dithionite concentration, considered to represent a good approximation to intra-erythrocyte O2 diffusion conductance, averaged (in mmol min-1 Torr-1 ml-1 RBC) 0.33 for chicken and 0.25 for duck (at 41 degrees C, pH of the suspension = 7.5, O2 saturation range 0.4-0.8). These species differences can be explained by differences in cell size, the RBC volume averaging 104 micron3 in the chicken and 155 micron3 in the duck. Compared with human RBCs, the G estimates for avian RBCs are somewhat smaller than would be predicted from size differences, which can be explained by the discoid shape of mammalian RBCs which constitutes an advantage compared with the ovoid avian RBC.
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