Document 3eb1owRjvgGzqBkQ1BO96kv3x

6?,, Cat*. Four cats Inhaled the. lone-fiber asbostes dust far periods of Hi, 2$t 33 and l'-2 months, respectively, ana -rrer* immediately sacrificed, Two other catr alter being expoaed te dust Tor IS months, lired ir. a normal atcospnere for an .ddltiooai 2k months. 70, flatc and Tyre of reaction, Exposure for 1it souths *ran sufficient to produce cellular accumulations of phagocytes around terminal bronchiole* end peripheral artariolte together with compact col lections of sisriJ ir calls in the tracheobronchial lymph nodes. It that time there war* no typical asbestosis bodies, but ecocth pointed Telle*- fibers *sr seen very rarely. "ith continued exposure. up to U2 months, reaction in the locations noted progressed to the foraation of cellular connective tissue which sade rell-defiaed sheaths about the respiratory bronchioles srd arterioles, marked lyapbcid hyper plasia. and lymphoid infiltration of brouchiolsr rails- The bronchiolar epithsliun was icrsr and flattened, giTing the tubes aaooth contour* Typical asbesto&ix bedims were not fenssd although there -rat* an occasional reHow, smooth, pointed fiber. Ho pisuriny tw present, the reaction -was similar in location to that in the guinea pigs, but fibrosis r?, such slcrar in deveiopaeut and had not reached th* same degree of maturity, f j.. Ji-har wvangee* Roentgenograms of Vtirm cats were rads after expoaur* periods of ?Af 33 end lv2 months, but tisp.v* changes wera not dens* enough to be ism on an I-r*y 2-lo- 72, Hats* Although 20 rata -were pLtcad in tua dust rocss, nany died from pnsuujortLa and rr not suitable for study. five toimals, of which ets was erposad for I? months and four for 25 aonthij, sere r*$ frve pulsooary infec tion end offer a basis for conclusions.