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PubMed1996

Development of the human fetal visceral pleura. An ultrastructural study.

The visceral pleura of human fetuses aged from 9 to 36 weeks of gestation was studied by means of transmission electron microscopy. The main components of the visceral pleura (mesothelium, basal lamina and submesothelial connective tissue layer) are formed in the fetal period. They develop asynchronously in different pleural areas, and do not reach maturity. Fetal differentiation of the lung pleura can be divided in two stages--early (until 17 gestation week) and late stage--up to birth. The high mesothelial cells appear later than the flat cells, but the first type predominates in the final covering layer during the period investigated. The most significant developmental phenomena of the mesothelium involve membranous differentiation (the microvillous covering, vesicular system and intercellular contacts). The different transport and secretory potentials of the mesothelial cells during the various prenatal periods are discussed. The mode of development of the basal lamina suggests its mesothelial origin. The elastic membrane appears during the late stage of fetal life. The components of the submesothelial connective tissue layer (fibroblasts, collagen and elastic fibres, blood and lymph vessels) undergo several phases of differentiation.

Cell Differentiation↗
PubMed2002

'Black Spots' and hyaline pleural plaques on the parietal pleura of 150 urban necropsy cases.

The absence of any direct connection between the lung and the parietal pleura raises questions about the mechanisms of pleural migration and retention of inhaled particles. It has been suggested that specific areas of parietal pleura absorb and retain inorganic particles from the pleural space, including carbon pigments and asbestos fibers, and could be starting points for pathologic changes induced by mineral fibers. These particle-collecting structures have been called "black spots." To study their distribution, macroscopic appearance, and possible relationship with pleural plaques, the parietal pleura of 150 consecutive necropsies of urban dwellers (mean age 67.7 +/- 12.9 years) were examined. The size and intensity of spots were scored and recorded on a computer scheme together with information of the presence of pleural plaques. Black spots were observed in 92.7% of the cases. They were mainly located in the lower costal and diaphragmatic zones and could correspond to the anatomic distribution of structures involved in pleural cavity clearance. Scores correlated with sex and age. There was no relationship between the predominant locations of black spots and hyaline pleural plaques.

Aged↗
PubMedDate not supplied

Calcifying fibrous pseudotumor of pleura: radiologic features in three cases.

PURPOSE: Our goal was to describe the radiologic features of calcifying fibrous pseudotumor (CEPT) of pleura. METHOD: Chest radiographs and CT images of three patients, aged 23-34 years, with pathologically proven CFPT of pleura were reviewed with regard to lesion size, location, and appearance. RESULTS: Chest radiographs showed well marginated, noncalcified pleural masses in all cases. Two patients had solitary masses and one had multifocal ipsilateral masses. All masses were located in the inferior aspect of the chest and measured 3-12 cm. All masses were calcified on CT. The calcifications were thick and band-like in two cases and punctate in one. There was no chest wall invasion, pleural effusion, or parenchymal disease. CONCLUSION: CFPTs of pleura are rare lesions that manifest as calcified pleural masses in young adults.

Adult↗
PubMed1983

Permeability of the canine visceral pleura.

Fluid and protein movement across the pulmonary endothelial membrane (PEM) and adjacent mesothelial layer of the visceral pleura was quantitatively analyzed in terms of a two-compartment model of fluid exchange. The left lungs of 13 spontaneously breathing anesthetized dogs were enclosed in a water-impermeable membrane, creating a visceral pleural space; fluid flux was determined as the filtration or reabsorption of water and protein in the visceral pleural space. Aortic, pulmonary arterial, left atrial, and pleural pressures were monitored; oncotic pressure was calculated from the protein concentration of plasma and pleural fluid. To determine the hydraulic conductivity (Lp), diffusional permeability (Pd), and the solute and solvent drag reflection coefficients for protein (sigma d and sigma f, respectively), fluid exchange was monitored during two or more experimental periods during which the visceral pleural space contained saline and plasma. The permeability coefficients determined for the PEM of the visceral pleura, Lp = 7.7 (+/- 0.3) X 10(-7) ml X s-1 X mmHg-1 X cm-2, sigma d = 0.93, sigma f = 0.61, and Pd = 2.4 (+/- 1.0) X 10(-6) cm/s, are more restrictive than those previously reported for the devascularized visceral pleura in vitro. We conclude that it is the pulmonary endothelial membrane that determines the rate and composition of visceral pleural fluid flux in response to hydrostatic and oncotic gradients in the intact animal.

Animals↗
PubMed1984

Comparison of amounts of collagen and elastin in pleura and parenchyma of dog lung.

Pressure-volume characteristics of the lung have been thought to be due primarily to the properties of the network of alveolar septa. However, Hajji et al. (J. Appl. Physiol.: Respirat . Environ. Exercise Physiol. 47: 175-181, 1979) attributed a substantial role to the visceral pleura. Seeking a structural explanation for this result, we compared the relative amounts of collagen fibrils and elastin fibers in the visceral pleura and alveolar parenchyma using stereological measurements in five canine lobes. We found about one-fifth as much collagen and one-tenth as much elastin in the pleura as in the alveolar parenchyma. This structural result confirms the functional conclusions of Hajji et al. We argue that such a substantial structure is not needed for protection against overinflation but may have to do with stabilization of lobe shape or handling of frictional forces.

Animals↗
PubMed1991

Permeability-surface area product and reflection coefficient of the parietal pleura in dogs.

The parameters describing the permeability of the parietal pleura to liquid and total plasma proteins were measured in five anesthetized adult dogs. Small areas of parietal pleura (approximately 1 cm2) and the underlying endothoracic fascia were exposed through resection of the skin and the intercostal muscles. The portion of the thorax containing the pleural windows was removed from the chest and fixed over a bath of whole autologous plasma, the inner parietal pleural surface facing the bath. Small hemispheric Perspex capsules (surface area 0.28 cm2) connected to a pressure manometer were glued to the pleural windows; a subatmospheric pressure was set into the capsule chamber to create step hydraulic transpleural pressure gradients (delta P) ranging from 5 to 60 cmH2O. Transpleural liquid flows (Jv) and protein concentration of the capsular filtrate (Cfilt) and of the plasma bath were measured at each delta P. The transpleural protein flux (Js) at each delta P was calculated by multiplying Jv by the corresponding Cfilt. The hydraulic conductivity (Lp) of the parietal pleura was obtained from the slope of the Jv vs. delta P linear regression. The average Lp from 14 capsules was 9.06 +/- 4.06 (SD) microliters.h-1.cmH2O-1.cm-2. The mathematical treatment of the Js vs. Jv relationship allowed calculation of the unique Peclet number at the maximal diffusional protein flux and a corresponding osmotic permeability coefficient for plasma protein of 1 x 10(-5) +/- 0.97 x 10(-5) cm/s. The reflection coefficient calculated from the slope of the linear phase of the Js vs. Jv relationship was 0.11 +/- 0.05.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1994

Permeability of parietal pleura to liquid and proteins.

The permselectivity of the parietal pleura was determined in spontaneously breathing anesthetized rabbits and dogs. In rabbits, we injected intrapleurally 5 ml of 1-g/dl albumin solution containing 100 microCi of 131I-labeled albumin plus 100 microCi of either lactate dehydrogenase (LDH) or alpha 2-125I-macroglobulin. Dogs received 100 ml of 1-g/dl albumin solution containing 100 microCi of 131I-albumin plus 100 microCi of alpha 2-125I-macroglobulin. A transpleural pressure gradient was set, lowering the intracapsular pressure to -30 cmH2O. The solvent drag reflection coefficients (sigma f) were calculated as the ratio between tracer concentrations in capsular and pleural liquid collected at 60-180 min. In rabbits sigma f was 0.44 +/- 0.2 (SD) for albumin, 0.84 +/- 0.1 for LDH, and 0.93 +/- 0.05 for alpha 2-macroglobulin. In dogs sigma f was 0.30 +/- 0.19 for albumin and 0.53 +/- 0.15 for alpha 2-macroglobulin. The hydraulic conductivity of the parietal pleura was 2.18 +/- 1.54 microliters.h-1.cmH2O-1.cm-2 in rabbits and 1.22 +/- 1.13 microliters.h-1.cmH2O-1.cm-2 in dogs. The parietal pleura could be modeled by two pore populations with radii of 83-89 and 156-222 A. The permeability coefficient averaged 0.08-0.21 x 10(-6) cm/s for albumin, 0.06-0.09 x 10(-6) cm/s for LDH, and 0.01-0.03 x 10(-6) cm/s for alpha 2-macroglobulin.

Animals↗
PubMed2002

Black spots of the parietal pleura: morphology and formal pathogenesis.

BACKGROUND: Dark incorporations (black spots) have been described in various organs. 'Black spots' seen as flat-to-nodular lesions of the parietal pleura are common findings in former miners. They represent areas of coal dust accumulation. An increased incorporation of asbestos fibres has been described in these areas, causing them to be seen as potential starting points for malignant mesotheliomas. OBJECTIVES: The aim of our examinations was to describe the morphology of black spots in order to understand their formal pathogenesis and discuss their role in the development of malignant mesotheliomas. MATERIALS: We report the results of the morphological and energy dispersive X-ray analysis of 12 black spots (4 surgical and 8 autopsy specimens) located in the parietal pleura. RESULTS: Black spots of the pleura develop in close correlation to lymphatic channels and blood vessels. Their formal pathogenesis is characterized by a mild fibrosis and an inflammatory reaction to the incorporated foreign particles. The proliferation of connective tissue may result in the formation of hyaline granulomas. Aluminum, silicone and sometimes fibres are also found in such areas. Mesothelial cells may be irritated. CONCLUSION: Although there are hints for an increased proliferation of mesothelial cells in some areas with black spots, our findings do not support the classification of black spots as an obligate early lesion in the development of malignant mesotheliomas.

Dust↗
PubMed1975

Postnatal development of the respiratory system of the opossum. II. Electron microscopy of the epithelium and pleura.

At birth, the opossum lung is remarkably primitive and consists of a system of branching airways that end in a number of terminal air chambers. From the newborn through the 10 cm stage of development the conducting portion of the lung predominates. The air chambers, which represent portions of the conducting system modified for respiration, are in a constant state of evolution since they are destined to become part of the expanding bronchial system. The airways are devoid of cilia and goblet cells at birth, and are lined by columnar epithelial cells which contain two types of cytoplasmic granules: an electron-dense form and a heterogeneous form. The latter exhibits an electron-dense core surrounded initially by a large halo of flocculent material. This type of granule is not seen beyond the 8 cm stage. The terminal air chambers of the newborn and later stages are lined type I and type II alveolocytes that appear identical to the alveolocytes lining alveoli in the adult. By the 2.5 cm stage, scattered cilia are present in the trachea and bronchi and bands of smooth muscle have differentiated in relation to bronchial epithelium and to proximal areas of the terminal chambers. Citiated cells are separated by ridges composed of light and dark cells which are without cilia and which contain scattered electron-dence granules. Throughout the postnatal period numerous alveolar macrophages and mast cells are noted in relation to the conducting system and pleura. Differentiation of the pleura also occurs during the postnatal period. In the newborn the pleura is simple squamous mesothelium. Later stages develop a thick connective tissue lamina between the pleural mesothelium and lung parenchyma. A large band of elastin is interposed between the mesothelium and underlying bundles of collagen.

Animals↗
PubMed1995

Effects of erythromycin on the rabbit pleura: its potential role as a pleural sclerosant.

Tetracycline (TCN) has been considered the agent of choice for pleurodesis in patients with symptomatic malignant pleural effusions and recurrent pneumothoraces. However, the intravenous form of TCN used for pleurodesis is no longer available. Erythromycin, like TCN, often produces irritation when administered intravenously. In view of these irritant properties, we tested the effect of erythromycin as a pleural sclerosant in rabbits as compared with TCN. Normal saline was used as a control. Adult rabbits weighing 2.5 to 3.0 kg underwent sterile placement of a silastic pleural tube in the right pleural space. Erythromycin (n = 17) or TCN (n = 6), each in doses of 35 mg/kg in 2 ml saline, was administered via the tube. Control animals (n = 6) received 2 ml saline. The chest tubes were left in place for removal of pleural fluid and to maintain lung expansion. Animals were killed 8 d after receiving the various treatments, and their pleural surfaces were examined grossly and histologically. Numerous adhesions were present between the visceral and parietal pleurae in all animals receiving erythromycin and TCN, but not in those receiving saline. On light microscopy, pleurae treated with erythromycin or TCN were histologically identical, showing inflammation, edema, and fibroblast proliferation in the submesothelial tissues. The saline-treated animals had a normal pleura. Because erythromycin produced pleural inflammation and adhesions within 8 d of treatment, we propose that it may have a potential role as a pleural sclerosant.

Animals↗
PubMed1998

Clara cell protein (CC16) in pleural fluids: a marker of leakage through the visceral pleura.

Pleural fluid (PF) proteins either derive from serum by diffusion or are locally secreted within the pleural space. Another hypothetical origin is a leakage of lung secretory proteins across the visceral pleura. To test this hypothesis, we investigated the occurrence, sources, and determinants in PF of CC16, a small-size and readily diffusible protein of 16 kDa secreted by bronchiolar Clara cells. CC16 concentration was determined by a sensitive latex immunoassay in serum and PF of 117 subjects (86 exudates and 31 transudates) and, for purpose of comparison, in ascites samples from another group of 38 subjects (7 exudates and 31 transudates). CC16 was also studied in serum and PF of normal rats and in rats with pleural exudate induced by alpha-naphthyl-thiourea (ANTU). The levels of CC16 in PF and ascites were highly correlated with that in serum, suggesting a diffusional exchange across the pleural/blood and peritoneal/blood barriers. Whereas CC16 occurs at similar levels in ascites and serum, the protein was found to be more concentrated in PF than in serum in both humans (geometric mean in microg/L, 26.2 versus 14.6, p < 0.0001) and rats (213 versus 16.2, p < 0.001). A local synthesis of CC16 appeared unlikely in view of the lack of CC16-immunostaining in pleura of both species. The only plausible explanation for these findings is that CC16 in PF originates from two sources: diffusion from plasma and a leakage from the lung into the pleural space across the semipermeable visceral pleura. This interpretation is supported by a markedly increased leakage of CC16 in experimental exudates induced by ANTU and the finding of high CC16 concentrations in human transudates associated with congestive heart failure, two conditions wherein PF has been shown to arise from the interstitial spaces of the lung.

Aged↗
PubMed1998

[A morphological study to elucidate the differences in visceral pleura in young and old mice].

The pleura is not only a mechanical envelope for the lung but also represents a crossroad for the exchange of cells and fluids. We studied ultrastructural differences in the visceral pleura of male mice in a young age group (aged 1 day, 1 week (wk), 2 wks) and an old age group (10 months (mos), 16 mos, 18 mos, 28 mos, and 30 mos), by both scanning and transmission electron microscopy. Surface microvilli (SMV) of mesothelial cells appeared to be sparse at day 1, then gradually increased in density and reached a plateau at approximately 10 mos. The length of the SMV changed in parallel with density which was confirmed by a morphometric study. After 28 mos, the SMV was partially loose, with an irregular and thin appearance. The morphological properties of pleural connective tissues, including collagen, elastin, and fibroblasts, changed in morphology with the changes in mesothelial cells; the elastic layer beneath mesothelial cells formed at 2wks and was maintained until 28 mos; collagen bundles increased in volume density throughout life, whereas cellular components including mesothelial cells, fibroblasts, and alveolar epithelial cells became atrophic with aging. From these observations, we concluded that although SMV do not have any known functions in the pleura, they change with age in a manner that likely corresponds to the changes in pleural connective tissue as well as structural changes in lung parenchyma.

Aging↗
PubMed1992

The role of closed pleural needle biopsy in the diagnosis of malignant mesothelioma of the pleura.

Malignant mesothelioma of the pleura is a disease that requires a biopsy procedure for a definitive diagnosis. In the past, closed pleural needle biopsy (CPNB) has given poor yields due to the small amount of tissue obtained, and the patient has subsequently been subjected to a diagnostic thoracotomy. In recent years, the availability of more accurate histopathologic tests have enabled the pathologist to make a diagnosis more easily on samples obtained at CPNB. In this retrospective study of 20 consecutive cases of malignant mesothelioma of the pleura diagnosed between 1980 and 1990, we found that a blind CPNB was diagnostic in five of seven procedures and CT-guided CPNB was diagnostic in five of six procedures. An open pleural biopsy (OPB) was diagnostic in ten of ten procedures performed. There were no complications associated with any of the CPNB procedures. We conclude that CPNB is a safe and effective manner of diagnosing malignant mesothelioma of the pleura, and should be attempted prior to OPB.

Aged↗
PubMed1997

Roles of the visceral pleura in the production of pleural effusion in permeability pulmonary edema.

We investigated the roles of the mesothelium of the visceral pleura on hydraulic conductivity in dogs under normal conditions and condition of permeability pulmonary edema. Nineteen mongrel dogs were divided into following 4 groups: thoracotomy alone (control group, n = 7); thoracotomy and striping of the mesothelium using Gelfilm (C + G group, n = 4); injection of oleic acid to increase the permeability of the pulmonary vessels (OA group, n = 4); injection of oleic acid and striping of the mesothelium (OA + G group, n = 4). A hemispherical capsule filled with physiological saline was attached to the visceral pleura. The transpleural fluid flow (delta V) was measured at given incremental or decremental hydrostatic pressures (delta Pcap) in the capsule. Hydraulic conductivity was calculated from the slope of linear regression line obtained from relationship between delta Pcap and the fluid flow rate (v) according to the Starling's equation. The conductivity obtained were 1.49 +/- 0.69 (nl.min-1.cmH2O-1.cm-2) in the control group, 1.37 +/- 0.88 in the C + G group, 3.75 +/- 0.74 in the OA + G group, and 7.07 +/- 2.49 in the OA + G group. The hydraulic conductivity was not increased by striping of the mesothelium (1.49 +/- 0.69 [nl.min-1.cmH2O-1.cm-2] vs. 1.37 +/- 0.88, in the control group vs. C + G group, respectively). Visceral pleural hydraulic conductivity following OA injection was increased by striping of the mesothelium (3.75 +/- 0.74 vs. 7.07 +/- 2.49 in OA group vs. OA + G group, respectively). These findings suggest that the wall of pulmonary vessels acts as a barrier to movement of pleural effusion under normal conditions, whereas the mesothelium of the visceral pleura acts as that under condition of permeability pulmonary edema.

Animals↗
PubMed2004

[Localized fibrous tumors of the pleura: clinical and surgical evaluation].

Solitary fibrous tumors of the pleura are uncommon and mainly arise in the pleura itself. Such tumors are generally asymptomatic and slow-growing. We report a series of 10 cases (8 men and 2 women with a mean age of 58.6 years) treated over a period of 54 months. The tumors were classified histologically as benign or malignant according to the criteria used by England. The treatment of choice was complete resection of the tumor. Six posterolateral thoracotomies and 4 video-assisted resections were performed. Histology showed a mixture of fibroblast-like cells and collagenous stroma. Sarcomatous degeneration was observed in the excised tumor of 1 patient. The patients were followed for a mean of 23.9 months. We conclude that although fibrous tumors of the pleura are considered benign histologically, complete resection and follow up for all patients are recommended.

Adult↗
PubMedDate not supplied

Benign solitary fibrous tumour of the pleura: a clinical review and report of six cases.

Primary tumours of the pleura are commonly divided into two major categories: diffuse and localised. Whereas the diffuse variant is known for its association with asbestos and its poor outcome, the localised one is rare and remains a subject of controversy. Electron microscopy and immunohistochemistry have recently demonstrated that these tumours are of mesenchymal rather than mesothelial origin, and therefore the term "localised mesothelioma" was abandoned. Such tumours are now called solitary fibrous tumours of the pleura (SFTP). The Authors describe a series of 6 cases of benign solitary fibrous tumours of the pleura, surgically treated over the period 1982-2000.

Adult↗
PubMed1990

[A case of malignant mesothelioma of the pleura].

An operative case of malignant localized mesothelioma of the pleura, a 63-year-old male, came to our clinic with the chief complaint of hemosputa. On suspicion of lung tumor, right upper lobectomy and lymph node cleaning were performed. The tumor was embedded in the lung; there was no infiltration into the chest wall. After the operation, radiotherapy was added but tumor recurrence occurred in the 5th month, and the patient died 7 months after surgery. From the form of the recurrence it was considered a diffuse-type transition case. The prognosis of this disease is known to be poor, but since there have also been cases of long survival, cases of resection are studied in Japan. Based on macroscopic tumor findings, cases of occurrence in the visceral pleura have poor prognosis if embedded in the lung, while cases of occurrence in the parietal pleura have varied prognoses, but the differentiation line is yet unclear. Among six cases of diffuse-type transition, including this case, five cases were of the histological type which included the epithelial component. Further study of these cases is necessary in the near future.

Humans↗
PubMed1985

Pleura in pneumothorax. Comparison of patients with cystic fibrosis and idiopathic spontaneous pneumothorax.

We studied pleura from patients with cystic fibrosis (CF) in order to define abnormalities that predispose to pneumothorax or are unique to CF. We compared the histology of CF pleura with that of young non-CF adults with "idiopathic" pneumothorax. Both CF and non-CF patients with pneumothorax showed distorted elastic fibers in areas of pleural fibrosis, adhesions, or air "cysts." Following pneumothorax, chronic inflammation, granulation tissue, fibrosis, mesothelial hyperplasia, and reactive eosinophilic pleuritis were also common. Although CF pleura appeared more intensely inflamed, only myxoid connective tissue and vascular proliferation were significantly more frequent in CF. Columnar, vacuolated mesothelial cells (Dunnill lesion) were focally observed only in patients with CF. We conclude that extensive degenerative pleural changes may predispose to pneumothorax in CF and represent a nonspecific response to chronic inflammation.

Adolescent↗