目的　进一步观察肉毒杆菌毒素A(BTA)所致的眼外肌形态学改变并探讨其作用机制。方法　用组化 3种方法 (HE染色 ,BEST卡红法 ,1%氯化金染色 )对注射BTA后不同时间的兔眼外肌行光镜下组织结构检查 ,并用透射电子显微镜观察其超微结构的变化。结果　注射BTA后 1周出现肌浆网的增多和扩张 ,线粒体的基质着色加深 ,肌糖原颗粒增多。注药后 1月眼外肌出现肌糖原纤维的节段性痉挛。注药后两月眼外肌出现不可逆萎缩。结论　BTA作用部位的眼外肌纤维出现节段性不可逆萎缩 ,随注药后时间的延长神经肌肉接头处神经再生 ,从而产生肌纤维的节段性增生 ,使眼外肌力得到部分或全部的恢复。 Objective To observe the morphological changes of extraocular muscle caused by botulinum toxin A (BTA) and to explore its mechanism. Methods The histopathology of rabbit extraocular muscles at different time after BTA injection was examined by light microscopy using the three methods of histochemistry (HE staining, BEST card red staining and 1% gold chloride staining). The ultrastructure of the rabbit extraoral surface was observed by transmission electron microscopy Structural changes. Results There was an increase and expansion of sarcoplasmic reticulum in the first week after injection of BTA, the mitochondria matrix was deepened and the muscle glycogen granules were increased. In January after injection of muscle extraocular muscle muscle spasm of muscle glycogen fibrillation. Irregular contractions of extraocular muscles occurred two months after injection. Conclusions The extraocular muscle fibers in the active site of BTA exhibit segmental irreversible atrophy. With the time prolonged after drug injection, nerve regeneration at the neuromuscular junction results in segmental hyperplasia of muscle fibers and partial or complete recovery of extraocular muscle strength.