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EXPERIMENTAL ASBESTOSIS--GROSS A DE TREVILLE 649 1. The characteristic early asbestotic le 9. The early chrysotile asbestotic lesion sion is situated in, and sharply localized to, in guinea pigs resembles that of rats, but it the proximal portion of the pulmonary ra- has not been adequately studied to permit cemus which, in the rat, consists of a very further characterization. short respiratory bronchiole and adjoining alveolar ducts. 2. Asbestosis in rats, caused by chrysotile This study was supported in part by Public Health ervioa grant OH 00132. Johns-Manville Company, through the courtesy of Kenneth W. Smith. MD. supplied the chrysotile asbestosis. dust, is nonprogreesive. 8. The evidence for the nonprogreeaive- References ness of chiysotQe asbestosis in rats consists of the observations that the minima] asbeetotic lesion is limited to the wall of the respiratory bronchiole and of the adjoining alveolar ducts and does not extend into ad 1. Roes, WX>., et al: Emotional Aspects of Reap)ratory Disorders Among Coal Miners, JAMA. 156*484 (Oct 2) 1954. Z Holt, P.F., and Young, D.K.: A Dust-Feed Mechanism Suitable for Fibrous Dust, Ann Oeeup joining normal alveoli and that the minimal Hyg 2:249,1960. asbestotic lesions heal by becoming collagenized and hypooellular. 4. The localization of the minimal asbes totic lesions is attributed to the proximal 8. Wright, B.M.: A Size-Selecting Sampler, for Air-Borne Dust, Brit J /ndustr Med 11:284,1954. 4. Gross, P,, and Tolker, E.B.: Dust Particles in Lung Sections: Some Notes on Methods of Their Visualization, Arch Environ Health 12:213. 1966. transport of dust from peripheral air spaces by the alveolar clearance mechanism and subsequent stagnation of the transported dust in the proximal portion of the racemus. 6. voc Hayek, H.: The Human Lung, VX, Krahl (irons). New York: Hefner Publishing Company, Inc, p 172. 6. Vorwald, A.J.; Durkan, T.M.; and Pratt, P.C.: Experimental Studies of Asbestosis, Arch lndustr 5. In rats chrysotile asbestotic lesions Hyg 8:1, 2051. heal in the absence of demonstrable (optical microscope) asbestos bodies and in the pres ence of chrysotile fibers, the latter becoming trapped in the scar tissue. 7. Gross, P.; P6txer. E.A.; and Hatch, T.F.: Al veolar Clearance: Its Relation to Lesions of the Re spiratory Bronchiole, Amer Rev Resp DU, 94:10, 1966. 6. Hatch. T.F.. and Gross, P.: Pulmonary Deposi 6. There is a considerable reduction in the amount of chrysotile dust found in the lung sections of rats one year or more after the imposition of the lung dust burden as tion and Retention of Inhaled Aerosols, New York: Academic Press, Inc., 1964, p 69. 8. Holt, PJ.; Mills. J.; and Young, D.K.: Early Effects of Chrysotile Asbestos Dust on Rat Lung. J Path Bact 87:15, 3964. compared with the amount of dust present 10. Gross, P.; deViUiere, AJ.; and deTrevillc, shortly after the dust burden was imposed. 7. The reaction of hamster lungs to chrys otile dust is the antithesis of that observed in rats. The lesion is progressive, extending R.T.P.: Experimental Silicosis, Arch Path 84:87-94, 1967. 11. Einbrodt, HJ.; KlosterkStter, W.; and Metze, H.: Vergleichende Untersucbungen fiber die Komgrtrsaen retinierter Staube in den Lungen von Mensch into peripheral air spaces so as to involve the entire racemus and thereby producing extensive consolidations leading to the death of the animals. The lesions do not heal, since the precollagenous stroma and und Tier. Beitr Silikosetorsch 6:491, 1963. 12. Groea, P.. and Smith, K.W.: Hie Topographic Distribution of Mineral Dusts in Some Pneumooooiotic Lungs, DU Chest 85:140, 1659. 13. Groes. P.: "Pathology of the Pneumoco nioses.*' in Lanza, AJ.L. (ed.): The Pneumoconioses, the high cellularity persists through the twoyear period of observation. At the same time, the amount of asbestos dust demon strable in the sections remains large and New York: Grune and Stratton, Inc., 1963, p SI. 14. Knox, J.F., and Beattie, J.: Mineral Content of the Lungs After Exposure to Asbestos Dust. Arch Jndustr Hyg 10:23. 1950. 15. Nagelschmidt. G.: Some Observations of the diffusely distributed. 8. The progressiveness of the chrysotile asbestotic lesion in hamsters is ascribed to a less effective pulmonary clearance mecha nism and to a greater reactivity of the pul Dust Cootent and Composition in Lungs With As- bestoaU, Ann HY Acad Set 132:64-76, 195516. Ray, S.C.; King. E.J.; and Harriaon, C.V.: The Action of Variable Amounts of Quartz oo the Lungs of Rats, Brit J Jndustr Med 8:62, 1951. 17. Siebert. F.T., and Fisher, E.R.: BronchioUr monary tissue than exist in rats. Emphysema, Amer J Path 83:1137, 1957. Arch Em>iron Hrofth--Vol 35, Not' 196? Panted end Putushed m r*e untied States of America 8005 1469 PRODUCED BY FORD