Abou Salem E A, Saito K, Ishikawa H
Department of Anatomy, Gunma University School of Medicine, Maebashi, Japan.
Arch Histol Cytol. 1993 Mar;56(1):49-63. doi: 10.1679/aohc.56.49.
The effects of tenotomy on the surface morphology of muscle fibers including myotendinous junctions in the rat soleus muscle were studied by scanning electron microscopy (SEM). Using potassium hydroxide (KOH) and collagenase, the extracellular materials were successfully removed to expose the surface of muscle fibers. When the soleus muscle was tenotomized at both proximal and distal ends, virtually all muscle fibers showed marked alterations of the fiber surface characterized by the formation of numerous transverse grooves and folds along their length. Narrow longitudinal grooves and folds of the sarcolemma were also observed. At myotendinous junctions, the fiber ends showed an over-all rounded shape with several short sarcoplasmic processes, indicating that the processes were significantly retracted. These changes were clearly recognizable at 5 days after tenotomy, and most apparent at one week. Thin-section electron microscopy of the same SEM samples demonstrated that such folding of the sarcolemma was not directly related to the sarcomere pattern of the underlying myofibrils, suggesting that, once formed, the folds and grooves were retained for a certain period of time. At 2 and 3 weeks the surface morphology of the fibers underwent a recovery process of restoring the smooth surface on which the cross-striations of the underlying myofibrils were seen. At the fiber ends, sarcoplasmic processes regrew into slender, wavy and short forms. Such sarcoplasmic processes were greater in number and more elaborate than those in the control muscle. At 5 and 6 weeks the fiber surface resumed an almost normal morphology, except that the sarcoplasmic processes at the fiber end were still shorter and more numerous than those in the control. These observations support our previous results obtained by thin-section electron microscopy that the myotendinous junction undergoes a series of morphological changes of collapse and regrowth of the sarcoplasmic processes, reflecting changes in the underlying myofibrils. In conclusion, the changes in the surface morphology of tenotomized muscle fibers were well correlated chronologically to those of myofibrils such as the central core lesion.
通过扫描电子显微镜（SEM）研究了跟腱切断术对大鼠比目鱼肌肌纤维包括肌腱结合处表面形态的影响。使用氢氧化钾（KOH）和胶原酶成功去除细胞外物质以暴露肌纤维表面。当比目鱼肌的近端和远端都进行跟腱切断术时，几乎所有肌纤维都显示出纤维表面的明显改变，其特征是沿其长度形成许多横向凹槽和褶皱。还观察到肌膜的狭窄纵向凹槽和褶皱。在肌腱结合处，纤维末端呈整体圆形，有几个短的肌浆突起，表明这些突起明显回缩。这些变化在跟腱切断术后5天清晰可见，1周时最为明显。对相同SEM样本进行的薄切片电子显微镜检查表明，这种肌膜折叠与下层肌原纤维的肌节模式没有直接关系，这表明一旦形成，这些褶皱和凹槽会保留一段时间。在2周和3周时，纤维的表面形态经历了恢复过程，恢复到可见下层肌原纤维横纹的光滑表面。在纤维末端，肌浆突起重新生长为细长、波浪状且较短的形式。这种肌浆突起的数量比对照肌肉中的更多且更复杂。在5周和6周时，纤维表面几乎恢复正常形态，只是纤维末端的肌浆突起仍然比对照中的更短且更多。这些观察结果支持了我们之前通过薄切片电子显微镜获得的结果，即肌腱结合处经历了一系列肌浆突起塌陷和再生的形态学变化，反映了下层肌原纤维的变化。总之，跟腱切断术后肌纤维表面形态的变化在时间上与肌原纤维的变化如中央核心损伤密切相关。
