Document o9ZbpXEX6nGoVdw63MyOMmGw3

16 month* ft dolloste fibrosis mado its appeeranoo. Tho process evolvod gradually and the number of fine Intercellular oollagenoue fiber* steadily Inaroeood. Aethie fibrosis contracted, it partially closed and distorted tho alveoli, and trlth this change the alveoli boooae.lined with cuboid*1 cellft. The recult iai an adenoma-llke appoaranoe which freqwntly io co'cnoalcs ehronia pulaonary inflammation resulting froxa many oaueaa. it deocrlbed a similar atme turn la the lunge of guinea pig* la* haling silicon carbldo. The longer exposure* to eebeetoe reeulted only In more thickonlng of tho voile of the air apseea, largely due to aa laoreaae In tho amount of flbroels. Tho flhroue tleeue always remained oellular and failed to show the hyallolratlon oharaotorletle of alllooale. Asbea* , tosle bodiee (fig. 3), flret seen-in the lunge of the guinea pigs that had Inhaled duct for about 2 nonthe, became more msnoroua and more die* tlactly sog&ontad with Increasing exposure. Tho reaction produood In guinea plga expoeod for 6 end 9 month# did not progroee significantly during a subsequent period of 35 end 37 month# when the anlnale lived in a nernal ataoephoro (figs. 0 and 7). Between. 8 and 11 months after exposure ceased, the cellular roaotlon In the lung had been completely replaced by thin strands of fibroue tissue. At later periods, tho soar tleeue vaa leas In amount but In tho laet animal sacri flood, 37 montha after discontinuing dust expo euro, sane flbroeia wee etlll vlelblo. TT^ " 10* tflllle, n.S. end Bruteaert, P. Tuaor-llko Stmoturea la the Lung* of Oulnea Plga Artificially Exposed to Silica Dust. Aa. Hoy. Tuboro. lit 268, 1928.