Document RjvJ8LoGKV3vGQgN68L3wEyeV

short-fiber asbestos was essentially the saoa as that already observed in the Qxperiawjt with Xirtg1 c floats asb-oton. The rats of reaction also was approxi- aately tha s-sos feot the extent of involriswnb with the snart-fibar dust was very raich less sad after 16 to 2li eaonth:: of nxpoeure only a vary few fcci of reaction, which generally required microscopic eranination for detection, were produced in the cadnea pigs. Until exposures had continued for approxiBately coo Tear, there was little tendency for dueb-cer.tainirg phagocytes to collect intc clasps. By 16 nonths phagocytes had befjen tc collect shout tho walls of a few of the respiratory bron chioles with a little proliforation or infiltration of sononaelear cells ia these walls. There were ;ilso soaa irultinucia&tsd cells but they were always of the inert fcrsign-body type. At 20 to 2k tenths the cellular ciuepa were sotaefclaee quite a&rked and aosstiaca changes in the epithaliua resulted in the adencesa-like or ?^de^srfctoid,, appaaraace previously described in Section IT. In aost of the subsequent Mahers of ths 3erics, tho reaction rocained cellular in type. In a fswt howsTer, fibrous elascats dominated the picture. In the Latter case, trie collages *w i*l3 in color ar.d tenuous uith no hearty swollen, hya.Td.nlta.tioa. As in the rats described below, iho alveolar wp-lli sight bo cade up of a bead of collagen supporting a layer of ardtheliUs*, hut with m contained capillaries. In the trechecbroasfei&l lyxph node*? the raaetion *5.3 ttoro pronounced in this erperl- nt than ia the prrficasf. cts with King' a .floats asbestos, probably beesuee of the trsssrpox^eticn of n excess of fine particl** to thfi nodes in arnrais inhaling shert-fib-sr aebweto.t., The reaction was **mbiaily on increase in rsticuiua, rattier then jl fifcrc4ie; i-ith preservation of tluj original cell& between the thickened reticular fiber*. Diffwe chronic plour1 tthout evidence of pulmonary infection pr*Bnt in 4 far v~' '