马杜霉素对不同虫株柔嫩艾美耳球虫超微结构的影响

鸡体内用5mg/kg马杜霉素作用于柔嫩艾美耳球虫（Eimeria tenella)敏感虫株和抗药虫株，比较裂殖生殖阶段超微结构的差异。敏感株型裂殖体体积变小，所生成裂殖子的数目变小，裂殖子膨胀，裂殖子间（带虫空泡内）微管膨胀，结构模糊，有髓鞘样结构出现；限制膜外突和细胞质分离形成空隙，膜结构模糊，有破损；细胞浆空泡化，出现附加体和髓鞘样结构；少数细胞核的外膜外突和内膜分离，有的部位的核膜模糊、破损。首次发现裂殖子顶体结构发生异常变化，棒状体消失，微线数目减少或者消失；线粒体表现为形态改变，嵴脱落，内部形成空泡、膜状结构和髓鞘样结构，线粒体的嵴与长辆平行排列，且贯穿线粒体。抗药虫株没有发现异常变化。推理抗生素类抗球虫药的作用机理为破坏虫体结构和抑制虫体的生理机能两个方面；球虫对该类药物产生抗药性的机制是基因突变和药物选择的结果。

The Ultrastructural Effect of Maduramasin to Different Strains of Eimeria Tenella

Two Eimeria tenella strains,one of which is resistant to maduramasin and the other is sensitive to it,were treated with 5mg/kg maduramasin,the ultrastructural difference between the two strains was observed and discribed.As for the sensitive strain,the meronts became smaller,and the number of merozoites in it decreased.The microtubules between them swelled,and the marrow sheathed figure between them was found.The merozoite membrane separated from the plasma,broke and was vague.The cell plasma vacuolated,swelled and the marrow sheathed figures and embody were found in it.The membrane of the nuclei was vague and swollen,and the outer membrane separated from the inner membrane. The rhoptry of the merozoite disappeared and the microneme of them reduced or disappeared.The form of mitochondrion changed,its cristae paralleled to the longititude axis and run through it,the cristae separated and turned into vacuole,the marrow sheathed and membrane figures were found in it. The changes of resistant strain were not found. The mechanism that the polyther ionophorous extinguish the coccidia is to destroy the structure and functions of them.The mechanism of the resistance is gene mutation and drug selection.