对位-二甲基氨基偶氮苯致癌过程早期之大白鼠肝脏組織学及組織化学覌察

HISTOLOGICAL AND HISTOCHEMICAL STUDY OF THE EARLY CHANGES IN THE RAT LIVER DURING p-DAB-INDUCED CARCINOGENESIS

1.大白鼠飼以含p-DAB膳食,第7天即見肝細胞胞浆嗜碱性物貭減少,并出現由嗜酸性細小顆粒聚集而成之"包涵体"状物。随肝細胞的退变及破坏,胆管上皮逐漸增生,至28天、肝小叶边緣大部被新生之胆管細胞所占据。殘存之肝細胞,有少部分呈現异常之肥大。2.肝細胞在p-DAB作用下,核糖核酸,糖元,蛋白貭結合硫氫基等均見減少,琥珀酸脱氢酶、非特异性酯酶活性减弱,伴以脂肪滴的出现和增多及碱性磷酸酶活性加强。3.肥大之肝细胞除偶见有"包涵体"状物外,大致呈现正常肝细胞的组织化学反应。4.肝细胞中出现的嗜酸性"包涵体"状物不被派若宁所着色,PAS反应阳性,硫氢基反应亦较强,碱性磷酸酶反应与胞浆其他成分一致。5.随胆管上皮之增殖,其核糖核酸,硫氢基,酯酶活性等逐见增加。新生的细胞具有碱性磷酸酶的强阳性反应。6.以上变化表示致癌物质对肝细胞的破坏作用和肝脏因而引起的反应性和代偿性的变化。

Thirty-nine male adult rats(body weight ranging 100—150 g)were selected,5 of them were fed with the basic diet and served as controls and the rest were fed with the same diet with p-DAB in addition(0.06 g/100 g diet).Sixteen of the latter group were kept until death with all of them developed hepatoma during 8—12 months,the remaining 18 were sacrified at the end of 4,7,14 and 28 days of p-DAB feeding.Specimens of the liver tissue were obtained from both the experimental and control groups for histological and histochemical examinations.The following methods were practised:methyl green-pyronin for ribonucleic acid(RNA);Barrnett-Seligman’s DDD reaction for protein-bound SH-groups;McManus-Hotchkiss’s periodic acid-Schiff’s reaction(PAS)for polysaccharides;SudanⅢfor fats;Gomori’s cobalt-calcium method for alkaline phosphatase(ALP);Nachlas-Seligman’s method for nonspecific esterase;and Nachlas et al.method for succinic dehydrogenase.The following facts were observed:1.In the cytoplasm of liver parenchymal cells,after p-DAB feeding for 7 days,there was a decrease of basophilia and the appearance of"inclusion bodies"which was formed by an accumulation of acidophil granules.The epithelium of the interlobular bile duct proliferated as the parenchymal cells degenerated,until 28 days,they invaded the periphery of liver lobules.Some of the residual parenchymal cells became hypertrophic.2.Under the action of the carcinogen,the degenerating parenchymal cells showed a decrease in content of RNA,glycogen,protein-bound SH-groups,a decline in succinic dehydrogenase and unspecific esterase activity,the appearance of fat globules and an increase in ALP activity.3.The histochemical picture of the hypertrophied parenchymal cells was essentially the same as that of the normal liver cells,except for the presence of occasionally observed"inclusion bodies".4.The"inclusion bodies"in the degenerating parenchymal cells were negative to pyronin staining,with positive reaction for PAS and strong reaction for SH-groups,while ALP activity was not distinguishable from that of the cytoplasm and other cell components.5.The RNA and SH content and esterase activity were all increased in the proliferating duct cells.These young cells showed strong positive reaction for ALP.The above results were discussed with contemporary theories of the action of DAB carcinogens and of the mechanism involved in the development of hepatoma.