Morphometric Basis of the Sheet-Flow Concept of the Pulmonary Alveolar Microcirculation in the Cat

doi:10.1161/01.RES.26.3.397

Home
/
Papers
/
Morphometric Basis of the Sheet-Flow Concept of the Pulmonary Alveolar Microcirculation in the Cat

Journal Article•DOI•

Morphometric Basis of the Sheet-Flow Concept of the Pulmonary Alveolar Microcirculation in the Cat

Sidney S. Sobin, Herta M. Tremer, Yuan-Cheng Fung

01 Mar 1970-Circulation Research (Lippincott Williams & Wilkins)-Vol. 26, Iss: 3, pp 397-414

TL;DR: The purpose of this study was to describe quantitatively the geometric organization of the pulmonary alveolar capillary bed as a tight network of circular cylindrical tubes and a suggested alternative of a continuous sheet bounded on two sides by endothelium held apart by connective tissue and cellular posts (sheet-flow model).

read less

Abstract: The purpose of this study was to describe quantitatively the geometric organization of the pulmonary alveolar capillary bed. Conventional representation of these vessels as a tight network of circular cylindrical tubes (tube-flow model) was contrasted with a suggested alternative of a continuous sheet bounded on two sides by endothelium held apart by connective tissue and cellular posts (sheet-flow model). A vascular space-tissue ratio, VSTR, is defined as the ratio of vascular lumen volume to the circumscribing tissue volume. The VSTR was obtained by planimetric measurements. Formulas were developed to relate VSTR to the geometric models. Cat lungs were perfused in situ with liquid silicone elastomer at 25 mm Hg, and the liquid elastomer was allowed to catalyze at 15 or 25 mm Hg static pressure while the airway pressure was maintained at 10 cm H 2 O. After the silicone became solid, the lungs were fixed with formalin-steam, and morphometric analysis was carried out on photographs of frozen sections. The mean values of VSTR of each cat (six lobes) were 0.91 to 0.92, irrespective of intracapillary pressure. These data are consistent with a sheet-flow model. Sheet thickness then becomes a significant variable.

...read moreread less

Citations

PDF

Open Access

More filters

Journal Article•DOI•

Scanning electron microscope study of the developing microvasculature in the postnatal rat lung.

[...]

J. H. Caduff¹, Lorenz Fischer¹, Peter H. Burri¹•Institutions (1)

University of Bern¹

01 Oct 1986-Anatomical Record-advances in Integrative Anatomy and Evolutionary Biology

TL;DR: The fact that true mature interalveolar septa show a denser capillary network than alveolar walls abutting onto pleura, bronchi, or larger vessels is consonant with the fusion theory.

...read moreread less

Abstract: During postnatal growth the parenchymal septa of rat lung undergo an impressive restructuring. While immature septa are thick and contain two capillary layers, mature septa are slender and contain a single microvascular network. Using the Mercox casting technique and scanning electron microscopy, we investigated the mode and the timing of the transformation of the pulmonary capillary bed. During the third postnatal week the parenchymal septa rapidly mature to match adult morphology. Even in adult lungs, however, remnants of the immature status are present: A capillary bilayer is regularly found at the base and the tip of the septa. Our observations support the concept that reduction of intervening tissue, partial fusion of the two capillary networks, and preferential growth lead to the mature vascular arrangement. The fact that true mature interalveolar septa show a denser capillary network than alveolar walls abutting onto pleura, bronchi, or larger vessels is consonant with the fusion theory. Towards the nonparenchyma, the capillary network surrounding every airspace had no counterpart to fuse with. From quantitative data it can be calculated that owing to lung growth, mesh size should increase more than four times between birth and adult age. The adult lung network, however, is denser than the one in young animals. This means that new meshes must be added during growth. We propose that small holes observed in sheet-like regions of the microvasculature enlarge to form new capillary meshes. With this mechanism of in-itself or intussusceptional growth, sprouting of individual capillary segments to increase network size is no longer needed.

...read moreread less

291 citations

Journal Article•DOI•

Stochastic flow in capillary blood vessels.

[...]

Yuan-Cheng Fung¹•Institutions (1)

University of California, San Diego¹

01 Jan 1973-Microvascular Research

TL;DR: It is shown theoretically that at a branching point of a capillary blood vessel the branch with a faster stream gets most of the red blood cells, thus explaining the extreme nonuniformity in hematocrit distribution in the capillaries.

...read moreread less

279 citations

Journal Article•DOI•

Regulation and repair of the alveolar-capillary barrier in acute lung injury

[...]

Jahar Bhattacharya¹, Michael A. Matthay•Institutions (1)

Columbia University Medical Center¹

11 Feb 2013-Annual Review of Physiology

TL;DR: Novel treatment strategies include the possibility of cell-based therapy that may reduce the severity of lung injury and enhance lung repair and the possible involvement of endogenous progenitor cells in strategically located niches in the lung.

...read moreread less

Abstract: Considerable progress has been made in understanding the basic mechanisms that regulate fluid and protein exchange across the endothelial and epithelial barriers of the lung under both normal and pathological conditions. Clinically relevant lung injury occurs most commonly from severe viral and bacterial infections, aspiration syndromes, and severe shock. The mechanisms of lung injury have been identified in both experimental and clinical studies. Recovery from lung injury requires the reestablishment of an intact endothelial barrier and a functional alveolar epithelial barrier capable of secreting surfactant and removing alveolar edema fluid. Repair mechanisms include the participation of endogenous progenitor cells in strategically located niches in the lung. Novel treatment strategies include the possibility of cell-based therapy that may reduce the severity of lung injury and enhance lung repair.

...read moreread less

255 citations

Cites background from "Morphometric Basis of the Sheet-Flo..."

...The lung’s unique hemodynamic properties are attributable to the so-called sheet structure of alveolar capillaries (8)....
[...]

Journal Article•DOI•

Morphometry of the human pulmonary vasculature

[...]

W. Huang¹, R. T. Yen¹, M. McLaurine¹, G. Bledsoe¹•Institutions (1)

University of Memphis¹

01 Nov 1996-Journal of Applied Physiology

TL;DR: The morphometric data on the branching pattern and vascular geometry of the human pulmonary arterial and venous trees are presented and the elemental and segmental data are presented.

...read moreread less

Abstract: Huang, W., R. T. Yen, M. McLaurine, and G. Bledsoe.Morphometry of the human pulmonary vasculature.J. Appl. Physiol. 81(5): 2123–2133, 1996.—The morphometric data on the branching pattern and vascul...

...read moreread less

252 citations

Cites background or methods from "Morphometric Basis of the Sheet-Flo..."

...(24) showed that the pulmonary capillaries can be described by a sheet-flowmodel....
[...]
...This technique has been used in the study of the morphology of the pulmonary vascular trees of cats (24, 29, 30), dogs (5), and rats (12)....
[...]
...The silicone elastomer used in the present study was the same as that used in the earlier studies; it is a clear and colorless fluid that can pass through the capillary bed (24) and has a low viscosity (4), a low surface tension (24), and a negligible volume change on catalysis (24)....
[...]

Other•DOI•

Structure and Composition of Pulmonary Arteries, Capillaries, and Veins

[...]

Mary I. Townsley¹•Institutions (1)

University of South Alabama¹

01 Jan 2012-Comprehensive Physiology

TL;DR: The need for rigorous quantitative approaches to study of vascular structure in lung is highlighted, bringing together information regarding classification of pulmonary vessels, branching geometry in the pulmonary vascular tree, and a quantitative view of structure based on morphometry of the vascular wall.

...read moreread less

Abstract: The pulmonary vasculature comprises three anatomic compartments connected in series: the arterial tree, an extensive capillary bed, and the venular tree. Although, in general, this vasculature is thin-walled, structure is nonetheless complex. Contributions to structure (and thus potentially to function) from cells other than endothelial and smooth muscle cells as well as those from the extracellular matrix should be considered. This review is multifaceted, bringing together information regarding (i) classification of pulmonary vessels, (ii) branching geometry in the pulmonary vascular tree, (iii) a quantitative view of structure based on morphometry of the vascular wall, (iv) the relationship of nerves, a variety of interstitial cells, matrix proteins, and striated myocytes to smooth muscle and endothelium in the vascular wall, (v) heterogeneity within cell populations and between vascular compartments, (vi) homo- and heterotypic cell-cell junctional complexes, and (vii) the relation of the pulmonary vasculature to that of airways. These issues for pulmonary vascular structure are compared, when data is available, across species from human to mouse and shrew. Data from studies utilizing vascular casting, light and electron microscopy, as well as models developed from those data, are discussed. Finally, the need for rigorous quantitative approaches to study of vascular structure in lung is highlighted.

...read moreread less

238 citations

Cites background from "Morphometric Basis of the Sheet-Flo..."

...Based on direct measurements accumulated from casts of the pulmonary vasculature or from transmission electron microscopy, average capillary diameter ranges from ~ 5-8 μm (6, 21, 37, 94, 97, 161, 255, 272, 291, 302)....
[...]

1
2
3
4
…
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22

Collapse

References

PDF

Open Access

More filters

Book•

Morphometry of the Human Lung

[...]

Ewald R. Weibel

22 Oct 2013

2,550 citations

Journal Article•DOI•

A morphometric study on the thickness of the pulmonary air-blood barrier

[...]

Ewald R. Weibel¹, Bruce W. Knight¹•Institutions (1)

Rockefeller Institute of Government¹

01 Jun 1964-Journal of Cell Biology

TL;DR: This analysis suggested that the gas conductance of the barrier is nearly optimal if one considers the mass of tissue and the minimal barrier thickness as fixed properties which are determined by other functional requirements on the alveolo-capillary membrane.

...read moreread less

Abstract: A reliable knowledge of the thickness of the alveolo-capillary "membrane" or air-blood barrier is of physiologic interest since it is intimately related to a quantitative estimation of such functional events as gas diffusion or tissue metabolism in the lung. The characteristic thickness of the air-blood barrier with respect to gas diffusion is its harmonic mean thickness, while the arithmetic mean thickness is related to the mass of tissue building the barrier and consuming oxygen in the lung. Two morphometric methods are proposed by which these two dimensions can be estimated from random measurements in the electron microscope in a reliable, simple, and efficient manner. By applying these methods to three rat lungs the arithmetic mean thickness of the barrier was found to measure 1.25 µ, the harmonic mean thickness, 0.57 µ. On the basis of these measurements a geometric model of the barrier in the form of a corrugated membrane was derived. Its dimensions showed close similarity to those of the natural barrier. This analysis suggested furthermore that the gas conductance of the barrier is nearly optimal if one considers the mass of tissue and the minimal barrier thickness as fixed properties which are determined by other functional requirements on the alveolo-capillary membrane.

...read moreread less

368 citations

"Morphometric Basis of the Sheet-Flo..." refers methods in this paper

...The statistical analysis of randomly cut thin sections of septa (1, 14) was found to be an unsatisfactory alternative to the optical sectioning technique for thickness determination for this study....
[...]

Journal Article•DOI•

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

[...]

J.B. Glazier, J. M. B. Hughes, J.E. Maloney, John B. West

01 Jan 1969-Journal of Applied Physiology

267 citations

"Morphometric Basis of the Sheet-Flo..." refers background in this paper

...(21), it is possible to extrapolate capillary width measurements in the isolated quick-frozen upright greyhound lung: at 10 cm H2O airway pressure, capillary width increases by approximately 0....
[...]
...That the alveolar vascular sheet is extensible and probably distensible is seen from studies of others on the effect of pressure on capillary filling (21)....
[...]
...(21), this is surprisingly close, especially when lung position is considered in the dorsal recumbent cat and the upright greyhound....
[...]

Journal Article•DOI•

Theory of sheet flow in lung alveoli.

[...]

Yuan-Cheng Fung, Sidney S. Sobin

01 Apr 1969-Journal of Applied Physiology

210 citations

"Morphometric Basis of the Sheet-Flo..." refers background or methods in this paper

...Theoretical treatment of alveolar sheet flow has been carried out separately by Fung and Sobin (2)....
[...]
...(2) The value and limitations of direct microscopical studies of the living lung through thoracic windows by modern recording techniques were noted in the introduction to this paper....
[...]
...This is due to (1) the higher viscosity of the silicone—approximately five times that of blood-and (2) the interracial surface tension between the hydrophobic silicone fluid (20....
[...]
...It is probably inert with respect to vascular smooth muscle, as indicated by (1) retention of vasoconstriction of the epinephrine or cold-constricted rabbit ear, compared to the contralateral control ear, and (2) extensive fining of the microvasculature of reactive hyperemic muscle compared to its contralateral control (11)....
[...]
...XXVI, March 1970 pressure on the pulmonary vascular system are identified: (1) the period of perfusion (flow) with a pressure drop from 25 mm Hg at the pulmonary artery cannula to zero at the aortic drain site while silicone polymer viscosity was low, to displace the contained blood; and (2) the period of static pressure (no flow) of 15 mm Hg or 25 mm Hg throughout the vascular bed of the lung before and during catalysis....
[...]

Journal Article•DOI•

Neural contrfl of intrarenal blood flow

[...]

BH Pomeranz, AG Birtch, AC Barger

01 Nov 1968-American Journal of Physiology

142 citations

"Morphometric Basis of the Sheet-Flo..." refers methods in this paper

...Although the silicone elastomer microvascular injection method has been increasingly used to study the functional geometry of the microvasculature of various organs (17, 18, 19), it had to be determined whether the characteristics of the alveolar capillary bed could conceivably result in excessive or abnormal microvascular filling with silicone polymer....
[...]