Laminated Membrane Surface and Osmiophilic Inclusions in Avian Lung Epithelium

Tyler, W. S.; Pangborn, Jack

doi:10.1083/jcb.20.1.157

Cited by 46 publications

(22 citation statements)

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“…On the contrary, there is considerable controversy concerning the configuration of the avian respiratory epithelium and of the ultrastructure of the different epithelial cell types. The morphological similarity between the granular atrial cells in bird species with type II pneumocytes of the mammalian lung has been reported (Tyler and Pangborn, 1964;Lambson and Cohn, 1968;Akester, 1970;Smith et al, 1986). These authors suggested that the osmiophilic lamellar bodies are related to the production of the avian acellular lining layer covering not only the walls of the atria but also the surface of the infundibula and air capillaries.…”

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confidence: 91%

An electron microscopic study of the parabronchial epithelium in the mature lung of four bird species

et al. 1997

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Background: No integrated comprehensive description of the ultrastructure of the parabronchial epithelium is available. The origin, discharge, and occurrence of the trilaminar substance have not yet been sufficiently studied. Therefore, the main objectives were to classify the cell types of the parabronchial epithelium and to describe their role in manufacturing the trilaminar substance. Methods: Lung tissue of mature quail, domestic fowl, town pigeon, homing pigeon, and barn owl was subjected to standard processing for transmission electron microscopy, both after intratracheal inflation and intravascular perfusion. Results: The atrial epithelium is constituted by granular and squamous atrial cells. Granular cells (1) are confined to the atrial wall; they produce and discharge osmiophilic lamellar bodies. Squamous atrial cells (2) manufacture and discharge a trilaminar substance in sheets sandwiched between the long microvilli emerging from the apical cytoplasm. Their attenuating cell outgrowths overlap granular cells. At the bases of atria, they pass as intermediate squamous atrial cells to the infundibula, contacting the extensions of squamous respiratory cells. The squamous atrial cells undergo distinct structural variations depending on age and environment. Squamous respiratory cells (3) (cellulae squamosae) continuously line the air capillaries and neighboring infundibula. They constitute the epithelial compartment of the blood-gas barrier. The cell bodies extend long, very thin cell outgrowths. The apical surface is smooth and the basal part is invested with a very thin basement membrane. The trilaminar substance originates from granular and agranular endoplas-mic reticulum in the form of convoluted profiles which are discharged as an acellular lining layer on the air surface of squamous respiratory cells. Conclusions: Granular cells are analogous to the type II cells of mamma-lian pulmonary alveolus. Squamous atrial and respiratory cells, of a common embryonic origin, do not meet any counterpart in epithelial cell populations of lung terminal airways in vertebrates. The specific trilami-nar substance-lipoproteinaceous in nature-is a constant compound of atria and air capillaries. Anat.

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An electron microscopic study of the parabronchial epithelium in the mature lung of four bird species

et al. 1997

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“…Cells that resemble mammalian Type I and Type I1 pneumocytes have been described in the late embryonic and adult chick lung (31). Turkey lung surfactant, like mammalian, is especially rich in PL and PC (18).…”

Section: Speculationmentioning

confidence: 99%

Lung Development in the Chick Embryo II. Choline and Ethanolamine Kinase Activity in the Developing Lungs of Normal and Hypophysectomized Chick Embryos

Compton

Goeringer

1982

Pediatr Res

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“…19). Cells resembling mammalian types I and I1 pneumocytes have been described by several investigators in the adult and embryonic chick lung (14,21).…”

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confidence: 99%

“…The major component of avian pulmonary surfactant is phosphatidylcholine (PC) (16,21). Two pathways are involved in the de novo synthesis of PC: the choline incorporation pathway (I) and the phosphatidylethanolamine (PE) methylation pathway (11).…”

Section: Speculationmentioning

confidence: 99%

“…19). Cells resembling mammalian types I and I1 pneumocytes have been described by several investigators in the adult and embryonic chick lung (14, 21).The major component of avian pulmonary surfactant is phosphatidylcholine (PC) (16,21). Two pathways are involved in the de novo synthesis of PC: the choline incorporation pathway (I) and the phosphatidylethanolamine (PE) methylation pathway (11).…”

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Lung Development in the Chick Embryo. I. Phosphatidylcholine Synthesis in the Developing Chick Lung

Compton

Goeringer

1981

Pediatric Research

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SummaryWe investigated the relative contribution cf the two pathways of phosphatidylcholine (PC) synthesis in lungs from chick embryos of 12 to 20 days of incubation as well as from hatched chicks and adult chickens. Lung "blocks" were incubated for 60 min in vitro in the presence of IgHlmethionine and [14Clcholine. P C was s e p arated by thin-layer chromatography, and the amount of labeled product was determined by liquid scintillation counting. P C synthesis (expressed as pmoles P C per mg protein per 60 min) by the choline pathway declined from the 12-day value of 40 to a minimum of 8 at day 16 and then rose gradually to a peak of 74 on day 1 posthatching. P C synthesis via the phosphatidylethanolamine pathway also declined from day 12 (9) to day 16 (13) but peaked on day 19 (65) and again on day 1 posthatching (9). Synthetic activities of the two pathways differed significantly (P 5 0.05) only on days 14, 18, and 19 of incubation. Unlike the mammalian lung, neither pathway seems to predominate throughout incubation or after hatching. The increase in P C synthesis towards the end of incubation correlates with the time of appearance of lamellar bodies in the lung epithelial cells and of surfactant in the airways. SpeculationBecause normal morphologic and biochemical development of the chick lung resembles that occurring in the mammalian lung in many respects, conclusions drawn from the study of avian lungs may well be germane to an appreciation of mammalian lung differentiation in general. Information concerning regulation of the biosynthetic pathways for phosphatidylcholine in the avian embryo may provide some clues for improved clinical treatment of certain pulmonary disorders, including respiratory distress syndrome of the newborn.Until recently, the question of whether or not the avian lung possessed surfactant was a matter of controversy (17). Now this material has been demonstrated lining the parabronchial, atrial, and air capillary membranes in the lungs of several avian species (18. 19). Cells resembling mammalian types I and I1 pneumocytes have been described by several investigators in the adult and embryonic chick lung (14, 21).The major component of avian pulmonary surfactant is phosphatidylcholine (PC) (16,21). Two pathways are involved in the de novo synthesis of PC: the choline incorporation pathway (I) and the phosphatidylethanolamine (PE) methylation pathway (11). Fetal and adult lungs of all mammalian species examined to date have been shown to possess the enzymes necessary for each pathway (1,6,7). ~h e ' c h o l i n e incorpdration has been identified as the maior route for PC svnthesis in the adult and late fetal mammalian l A g (5). No studieg have been published on the pathways for PC synthesis in the embryonic, newly hatched, or adult chicken lung.We investigated the production of PC in blocks of lungs from chicks of different ages. The blocks were incubated in the presence of radioactive precursors specific to the two pathways for PC synthesis. This provided us with a measure of the r...

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Laminated Membrane Surface and Osmiophilic Inclusions in Avian Lung Epithelium

Cited by 46 publications

References 7 publications

An electron microscopic study of the parabronchial epithelium in the mature lung of four bird species

An electron microscopic study of the parabronchial epithelium in the mature lung of four bird species

Lung Development in the Chick Embryo II. Choline and Ethanolamine Kinase Activity in the Developing Lungs of Normal and Hypophysectomized Chick Embryos

Lung Development in the Chick Embryo. I. Phosphatidylcholine Synthesis in the Developing Chick Lung

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