正常人眼外肌组织学初步研究

Histiocytic study of extraocular muscles of normal human

目的探讨正常人眼外肌组织细胞学结构并通过组织化学染色法对眼外肌纤维分类。方法10条正常人眼外肌分为肌腹部、赤道部和近肌腱部,行肌球蛋白三磷酸腺苷酶(mATPase)和还原型辅酶Ⅰ四唑氮还原酶(NADH-TR)染色,测量肌纤维及构成比。另15条正常人眼外肌,行常规组织病理学染色和Masson染色。结果正常人眼外肌在肌腹部可分为眶层和球层;赤道部无明显分层,肌肉周边部有斜行或横行肌纤维伴较多结缔组织穿插,肌肉外周包绕增厚胶原结缔组织环。近肌腱部为球层肌纤维。组织化学染色可将眼外肌纤维分为5类,肌腹部、赤道部和近肌腱部各类肌纤维比例不同。结论人眼外肌结构独特,分为不同肌纤维特点的眶层和球层,球层通过肌腱附着于巩膜,眶层终止于眼球赤道部的Pulley结构。组织化学染色法可将眼外肌纤维分类,不同位置的肌纤维构成不同。

Objective Extraocular muscles are special skeletal muscle with unique structural properties. Histochemical and ultrastructural analysis have demonstrated that the conventional muscle fiber classification schemes are not applicable to the extraocular muscles. This study was to investigate the histiocytic structure of extraocular muscles of normal human and classify the muscle fibers in the basis of histochemical result. Methods Ten extraocular muscles harvested from normal donors aged from 22 to 31 years were cut in different muscle planes （midbeIIy, equatorial and distal part）, and consecutive transversal cryostat sections were stained with nicotinamude tetrazolium reductase（NADH-TR） and myosin-adenosine triphosephatase （mATPase） following alkaline and acid preincubations. The types of muscle fibers were identified based on their staining characteristics in the consecutive sections. And the distribution and perimeter of different types of fibers were assessed. The haematoxylin and esoin （HE） and Masson＇ s trichrome were performed for the consecutive transversal sections in 15 normal human extraocular muscles. Results The normal human extraocular muscles were divided into orbital and global layers with different types of fiber in the midbelley part. At the equatorial part, the extraocular muscles could not be classified distinctly with a thickened sleeve-like collagen ring. Some fibers in the peri-muscle were slanted and fused into connective tissue. Only the fibers of global layer were presented in the distal extraocular muscles with abundent connective tissue. Histochemical study result indicated that there were five types of fibers：orbital layer singly innervated muscle fiber, orbital layer multiply innervated muscle fiber, global layer coarse fiber,global layer granular fiber and global fine fiber. The distributions and amount of different types of fibers varied upon the different muscle portions. Conclusion Extraocular muscle consist of orbital and global layer in midbelley. Global layer fibers via muscle tendon insert onto the scalera and the orbital layer fibers inserted into the Pulley near the global equator. Extraocular muscle fiber types could be classified with bistocbemical study.