Document LpkDjMw8GLQ1xD5DR5mv1zrez

EXPERIMENTAL A8BE8TOS1B--QROS8 A DE TREVJLLS 646 were bundles of smooth muscle that often encroaching upon the lumens. Occasionally, constituted masses 50p to 100/i in thick the argyrophilic stroma extended into the ness (Fig 6). These muscle bundles were lumen of an alveolar duct or a bronchiole in sharply delimited and related to the wall of a polypoid manner, occluding it The con thickened alveolar ducts. They had no con densation of thin argyrophilic fibers to form nection with blood or lymph vessels nor parallel thick fibers devoid of arboresoence could a relationship to the muscularis of a and the transformation into collagen, char terminal bronchiole be demonstrated. In the acteristic of the lesions in rats, was not seen newly formed connective tissue about some at all or to a very minor extent in these of the alveolar ducts and respiratory bron hamsters. For the most part, the occlusion of chioles, there were scattered gland-like the air spaoes was caused mainly by massed structures. These pseudo-glands represent alveolar cells, but the contribution of the ar- surviving units of the evaginating alveoli gyrophilic stroma should not be dismissed. that have become lined by tall columnar epi It should also be emphasized that in con thelium, occasionally ciliated. No acid-insol trast to the situation in rat lungs where the uble mineral ash was demonstrable in the involvement was sharply limited to the al area- occupied by the proliferated muscle veolar duct and its evaginating alveoli, there fibers. The regions, pervaded by the more was no such delimitation in the hamster cellular and active inflammation, some con lung. Here, the cellular as well as the stro taining leukocytes, were also devoid of de mal proliferation extended without abate monstrable mineral ash. ment to the peripheral alveoli, thus aooount- Hamsters (Intratracheal Injection).--Of ing for the diffuseness of the consolidation. 19 hamsters, 16 died as a result of the ashes- Following incineration, abundant acid- totic inflammation that followed the intra insoluble mineral dust was observed in the tracheal injection of chrysotile dust. The involved reoemi, Many individual fibers three survivors had received only one injec could be identified; some straight or wavy, tion and were killed 21 months after the im others coiled and forming tangled masses. position of the lung dust burden. The aver Compared with the amount of dust found in age survival of the hamsters that had one rat lungs, the chrysotile dust in the hamster intratracheal injection was 16% months, lungs was much more abundant and more with a range of 13% to 20Vi months. The diffusely distributed (Fig 9). Asbestos bod animals that had received two intratracheal ies were found in abundanoe throughout the injections survived, on the average, 14% affected regions. They were considerably months from the time of the first injection, smaller than those seen in human lungs but with a range of 12% to 16% months. The were readily recognized. They were best three survivors that were killed after 21 seen under dark-field illumination with dry months were emariated and also had exten objectives in unstained sections (Fig 10). sive asbestotic disease. Many of the lung sections showed exten sive consolidation with relatively few patent air spaces. In other lung sections, the consol idation was patchy, Beemingly oonoentrated about larger air spaces with relatively little aerated tissue between the consolidated por However, there was no parallelism between the number of luminescent asbestos bodies seen in the unstained sections and the amount of dust found in the same field after microincineration. The amount of dust pres ent was much greater than might be sus pected from the number of asbestos bodies tions. The consolidated portions were com obeerved. Most of the dust and the asbestos posed of masses of cells with vesicular round or oval nuclei--apparently alveolar cells (Fig 7). Leukocytes were not seen. Al veoli or larger air spaces usually could not be identified in these regions except after silver impregnation (Fig 8). The argyrophil- bodies were situated in the air spaces. When observed within tissue, the asbestos bodies and the dust were found trapped within the network of inflammatory argyrophilic fibers and associated oells that tended to occlude the air spaces. ic mural stroma of all air 6paoes in the solid Guinea Pigs (Inhalation).--Barely recog ified regions was greatly thickened by ar nizable, minimal mural thickening of an oc borescent fibers that formed a loose network casional alveolar duct and respiratory bron- Arch Environ Health--Vol IS, Nov 1967 8005 1465 PRODUCED BY FORD