家兔小腿三头肌肌亚部区分和运动终板分布的观察

用家兔小腿三头肌做肌亚部区分和运动终板分布的研究。结果表明，腓肠外侧头可分为三个肌亚部，各肌亚部有一支一级神经支和一条运动终板带；腓肠肌内侧头和比目鱼肌无区分肌亚部的形态特征。作者认为，腓肠肌外侧头区分的肌亚部与运动终板的分具有相关性。用大体解剖法区分的肌亚部可通过肌运动终板的分布验证。     

家兔腓肠肌亚部神经切断对其肌内神经、运动终板和肌梭的影响

目的　切断家兔腓肠肌外侧头肌亚部神经后 ,观察肌内神经、肌梭、运动终板带、肌湿重等的形态学变化。方法　 4 0只家兔随机分成对照组和神经切断组。用Sihler s肌内神经染色法染肌内神经 ;用乙酰胆碱脂酶整肌染色法染肌运动终板 ;用HE染色法染肌梭。结果　 (1)术后 2周亚部肌湿重明显下降 (P <0 0 5 ) ,肌运动终板带模糊不清 ,肌内神经染色变浅 ,三级分支消失 ,但肌梭形态及梭内肌纤维尚无明显改变 ;(2 )术后 4周肌湿重进一步下降 (P <0 0 1) ,运动终板带完全消失 ,肌内二级分支染色无 ,肌梭形态及数量有改变 ;(3)术后 12周肌肉明显萎缩 ,发生纤维化 ,运动终板带无 ,肌内神经染色无 ,仅留有鞘管样结构 ,未见神经再生 ,肌梭形态、数量明显改变 ;(4)术后 16周各参数与 12周相比差异无显著性。邻近正常肌未见有侧支神经支配失神经的亚部。结论　 (1)家兔腓肠肌外侧头各亚部在神经切断术后 4周 ,运动终板、肌梭的数量和形态有改变 ;(2 ) 12周后肌内神经染色仅有神经外膜鞘管样结构残存 ;(3)术后 16周末见原位的神经再生和相邻亚部神经侧支的再支配。     

小白鼠股直肌的肌纤维类型及运动终板配布的组织化学研究

本文用琥珀酸脱氢酶(SDH)和乙酰胆碱酯酶(AchE)结合染色法,研究了小白鼠股直肌的三种肌纤维的分型和运动终板的配布。观察结果表明,股直肌纤维由深层至浅层红肌递减、白肌递增,在深层缺少中间肌,而中间肌在中浅层分布无明显差异。白肌纤维占40%,红肌纤维占34%,中间肌纤维占25%。白肌纤维最大直径70±9.25um,最小直径39.4±7.63um;红肌纤维最大直径41.66±5.54um,最小直径24.8±5.01um;中间肌最太直径53.35±6.82um,最小直径29.6±4.76um。白肌纤维上的运动终板数量占运动终板总数的77.2%,红肌纤维上的运动终板占运动终板总数的13.9%,中间肌纤维上的运动终板仅占运动终板总数的8.8%.     

家兔趾深屈肌肌构筑、肌内神经和运动终板分布

目的:探讨家兔趾深屈肌的肌构筑与肌内神经和运动终板分布的关系。方法:肌构筑法、改良Sihler s染色法、乙酰胆碱酯酶染色法。结果:家兔趾深屈肌为环羽肌。肌质量为(2.30±0.02)g,肌纤维长(1.00±0.01)cm,肌生理横切面积(2.17±0.12)cm2。肌的起端,神经干于腱板上方发出内侧和外侧两条初级支,初级支在肌内发出数目不等的次级支,继而向肌的深面和边缘发出终末支。有的次级支穿越腱板到达对侧。肌表面内、外两缘有线状排列的运动终板带,两带在肌止端相接,呈“V”形。结论:家兔趾深屈肌是环羽肌,倾向力量型设计;肌内神经分支存在越边支配;肌内神经和运动终板的分布与肌纤维排列有关;趾深屈肌有划分亚部的形态学特征。     

制作运动终板电镜标本的一种简单方法

在运动终板的超微结构形态学研究中,由于在半薄切片中寻找到运动终板比较困难,因而在电镜下难以观察到运动终板,特别在长肌中要在电镜下观察到运动终板更加困难。由此导致在电镜制样时,工作量大;在电镜观察时,失败概率高。我们在工作实践中,逐步摸索出一种比较容易观察到运动终板的制样方法,即将长肌及其支配神经进行整体包埋,以神经进入肌束处为标志进行半薄切片,便于在半薄切片中寻找到运动终板,然后进行定位,再进行超薄切片观察的方法,现简要报道如下:1　标本的取材　捣毁蟾蜍脑脊髓,处死蟾蜍。剥皮去内脏后,将蟾蜍下半身固定于蛙板上,腹…     

氯化金法浸染运动终板的改进

氯化金法浸染运动终板的改进高杰，田应（沈阳市中国医科大学脑研究所１１０００１）显示神经末梢的方法很多，大致可分为银浸法，氯化金浸染法和美兰超生体染色等三类。我们体会氯化金浸染法对显示运动终板的整体构造效果较佳。具体的操作步骤如下；１．取新鲜眼球外肌或...     

软骨终板的形态与椎间盘退变的关系

软骨终板位于椎体上、下表面与椎间盘的纤维环和髓核之间 ,刘润田〔1〕等认为是椎间盘的一个组成部分 ,另一些学者〔2〕认为椎体上、下表面的皮质外层。软骨终板和纤维环一起将胶状的髓核密封 ,使椎间盘形成一个自行限制的密闭容器 ,起缓冲外力的作用。若软骨终板破裂 ,髓核会通过其破裂处突入椎体骨质内形成许莫结节 ( Schmorl) ;或向后突入椎管内形成椎间盘突出。本文就软骨终板的形态和功能作一综述 ,旨在为椎间盘退变的进一步研究和人工椎间盘置换术等临床应用提供解剖学依据。椎间盘是人体最大的无血运组织 ,其营养途径主要有 :( 1 )…     

终板凹陷角变化对腰椎运动节段生物力学影响的有限元分析

目的:研究终板凹陷程度变化对腰椎运动节段生物力学影响。方法:在以往建立的腰椎L4～5运动节段三维非线性有限元模型基础上,采用CAD方法精确构建三种不同终板凹陷角改变的有限元模型,有限元模型的椎间盘前凸角、小关节间隙等其余形态学参数及网格划分均保持一致。垂直压缩、屈曲、伸直、前后剪力5种载荷条件下,分别对三种有限元模型生物力学参数进行测试。结果:负载条件下,终板凹陷角增加、终板凹陷程度减小可导致终板-椎间盘界面应变减小,椎间盘刚度及髓核内压增加,椎间盘膨出、纤维环纤维张应力、纤维环基质应力、腰椎后部结构应力以及关节突接触力减小。结论:终板凹陷程度的减小增强了椎间盘对椎体的保护作用;同时可通过影响终板的形变减少对椎间盘的营养传递。     

兔腓肠肌肌亚部神经挤压后肌内神经、运动终板和肌梭等的变化

目的　本文旨在通过建立肌亚部神经挤压损伤的模型 ,以肌内神经、肌梭 ,运动终板带、肌湿重等为参数观察神经的损伤及修复。方法　 1.用sihler’s肌内神经染色法染肌内神经。 2 .用乙酰胆碱脂酶整肌染色法观察肌运动终板带变化。 3.用HE染色法观察肌梭。结果　实验组手术后两周肌亚部轻度萎缩 (肌湿重P <0 0 5 ) ,运动终板带变绍颜色变浅 ;肌内神经连续性存在 ,但三级末梢染色浅淡甚至消失 ;肌梭形态无明显变化。手术后五周到六周肌湿重增加 ,肌内神经着色深 ,三级末梢清晰可见 ,肌外观基本恢复正常。与其他亚部相比 ,腓肠肌内侧亚部各参数恢复较快。手术后八周所有各参数恢复与对照组比较无显著性差异 (肌湿重、肌梭密度p >0 0 5 )。结论　 1.家兔腓肠肌外侧头各亚部在神经挤压损伤六周后肌内神经分支分布恢复至正常形态 ,神经末梢感受器及运动终器恢复。 2 .在亚部水平神经被挤压后 ,神经的再生与修复速度较整肌更早 ,更快     

家兔跖肌肌内神经、运动终板及肌梭的分布

目的 :探究家兔跖肌肌内神经、运动终板及肌梭的分布。方法 :改良Sihler’s染色法、乙酰胆碱酯酶染色法及HE染色法。结果 :肌的起端 ,神经主干上发出若干细小分支 ,尤以内侧部为多 ;肌的中上部 ,可见 2～ 4条“L”形初级支 ,分布到内侧部肌纤维 ;3～ 5条初级支 ,穿越肌内腱膜板后司外侧部肌纤维。运动终板呈线状排列于跖肌两缘 ,矢状和冠状切面上可见“V”形终板带 ,横断面上呈“S”型。肌梭密度为 (16 .94± 1.72 )个 / g。 结论 :家兔跖肌的肌内神经、运动终板和肌梭分布与肌纤维排列有关 ;肌内神经分支密集的部位 ,运动终板聚集呈带状 ,肌梭密度高 ;跖肌具有划分亚部的特征。     

Polyneuronal innervation of skeletal muscle in new-born rats and its elimination during maturation.

1. The events taking place during the elimination of polyneuronal innervation in the soleus muscle of new-born rats have been studied using a combination of electrophysiological and anatomical techniques. 2. Each immature muscle fibre is supplied by two or more motor axons which converge on to a single end-plate. There was no sign of electrical coupling between muscle fibres receiving multiple synaptic inputs. By the end of the second week after birth virtually all muscle fibres are innervated by only a single motor axon. 3. The average tension produced by individual motor units, measured in terms of the percentage of the total muscle twitch tension, declined dramatically during the first 2 weeks after birth. During this period there was no significant change in the number of motor neurones innervating the soleus muscle. Thus, the disappearance of polyneuronal innervation reflects a decrease in the number of peripheral synapses made by each motor neurone. 4. The decline in motor unit size was delayed, but not ultimately prevented, by the early surgical removal of all but a few motor axons to the soleus muscle. This procedure also caused a delay in the removal of polyneuronal innervation involving the remaining motor units. 5. Following a crush of the soleus nerve in neonatal animals, regenerating axons usually returned to the original end-plates. Polyneuronal innervation was extensive at early stages of re-innervation and it disappeared during the second week after birth just as in normal muscles. 6. Cross-innervation of neonatal muscles by an implanted foreign nerve caused a rapid disappearance of cholinesterase at denervated original end-plates and in most fibres prevented re-innervation by the original nerve. In the small proportion of fibres that did become innervated through both the foreign and original nerves the end-plates were more than 1 mm apart, and both foreign and original nerve end-plates could persist indefinitely. 7. Many cross-innervated fibres received multiple inputs through the foreign nerve. Some foreign end-plates were separated by distances ranging up to 1 mm. Polyneuronal innervation through the foreign nerve was completely eliminated during maturation but over a slightly longer period than in normal muscles. Apparently the elimination process can act over a distance up to but not much more than 1 mm. 8. These observations suggest that there are several factors influencing the elimination of redundant inputs in immature muscles. Individual motor neurones appear to have an inherent tendency to withdraw the majority of their original complement of peripheral terminals. The determination of which particular synapses are to survive, however, seems to be made in the periphery by a selection among all the synapses that innervate a limited region of each muscle fibre. There may be a competitive interaction among synapses in which those belonging to smaller motor units are less likely to be eliminated, thereby leading to a relatively uniform size of the motor units in the soleus.     

Estimation of the number and size of motor units in intrinsic laryngeal muscles using morphometric methods

The number and size of motor units in the intrinsic laryngeal muscles were estimated by morphometric methods. Laryngeal muscles with their respective nerve branches were obtained from 64 fresh cadavers (32 older than 60 years, mean age 74 +/- 9 years and 32 younger than 60 years, mean age 51 +/- 8 years). Myelinated nerve fibers and the total number of muscle fibers were counted. Motor unit size was estimated by dividing the total number of muscle fibers by the total number of motor units in each case. The mean number of motor units ranged from 268 +/- 1.3 (interarytenoid muscle) to 431 +/- 1.6 (cricothyroid muscle). Thyroarytenoid and cricothyroid muscle presented the smallest (9.8 +/- 0.2) and largest (20.5 +/- 0.9) motor unit size, respectively, suggesting that thyroarytenoid muscle has a greater capacity to fine-tune its total force compared with the other intrinsic laryngeal muscles. No differences in motor unit number or size were observed between the right and left sides or between younger and older subjects. It is suggested that synaptic rearrangements may occur at the level of the neuromuscular junction in the human larynx that may explain the age-related changes in motor units reported by clinical methods.     

A study of frog muscle maintained in organ culture

1. Frog muscles are isolated and maintained in organ culture conditions for periods of up to 2 months. During the first 2 weeks, muscle fibres have normal resting membrane and action potentials. Subsequently the potentials decline in amplitude.2. Slow muscle fibres also survive in culture and retain their ability to give maintained contractures.3. Muscle sensory receptors continue to function in culture until the axon terminals degenerate at about 2 weeks.4. Neuromuscular transmission is normal during the first few days of culture, after which the motor endings degenerate. Transmission persists longer (up to 17 days) if a long segment of nerve is left attached to the muscle. With short-nerve preparations failure of transmission in vivo occurs at about the same time as in culture. With long-nerve preparations failure of transmission is delayed even further in culture.5. In short-nerve preparations miniature end-plate potentials disappear, in general, at about the time that transmission fails. In long-nerve preparations some end-plates continue to have miniature end-plate potential activity for a short time after nerve impulses cease to evoke any response; but eventually miniature potential activity disappears from all end-plates.6. After a few days of electrical silence, miniature end-plate potentials reappear at some of the denervated end-plates. The proportion of denervated end-plates which show miniature end-plate potentials in culture is smaller than in muscles denervated in situ.7. Electron microscopy shows that muscle structure is well preserved in culture, that the axons degenerate and that the Schwann cells move to occupy the space vacated by the axons. The Schwann cells are very probably the source of the acetylcholine which evokes miniature potentials in the denervated end-plates.     

Nerve implants in botulinum poisoned mammalian muscle

1. In albino rats the botulinum poisoned gastrocnemius muscle was supplied with an accessory motor nerve in order to investigate whether muscle fibres with structurally intact but non-transmitting synapses would accept additional innervation. As a control similar operations were made in unpoisoned rats.2. One to three months after nerve implantation the muscles were examined histologically for the presence of a new end-plate zone. In botulinum treated muscles 1662 +/- 165 (mean +/- S.D.) of new end-plates were found. In the control animals only a few (90 +/- 13) were observed in the immediate vicinity of the implanted nerve trunk.3. Following recovery from the paralysing action of botulinum toxin electrical stimulation of both the implanted and the original motor nerve evoked strong mechanical twitches in the gastrocnemius muscle.4. When the nerves were stimulated simultaneously little or no summation of tension occurred, indicating that presumably many of the muscle fibres with new end-plates also had functionally intact junctions from the original nerve. The presence of two end-plates in a muscle fibre was confirmed in a few experiments on single curarized fibres by intracellular recording of end-plate potentials on stimulation of each nerve.     

Sprouting of frog motor nerve terminals after long-term paralysis by botulinum type A toxin

A single sublethal injection of botulinum type A toxin (BoTx-A) to winter frogs induced a general and complete paralysis of skeletal muscles, which lasted several months. Quantitative analysis of 483 end-plates from 8 BoTx-A poisoned muscles and 495 endplates from 8 control muscles revealed a higher and significant incidence of terminal and ultraterminal sprouts in poisoned junctions when taking into account the normal remodelling of motor innervation. We conclude that prolonged neuromuscular blockade by BoTx-A results in the extension of the nerve terminal arborization.     

Cholinergic Receptors at Denervated Mammalian Motor End-Plates

The number of acetylcholine receptors at normal and denervated end-plates in rat soleus muscles was studied using the binding of [¹²⁵I] α-bungarotoxin as a quantitative assay. Normal end-plates bound several thousand times as much toxin as equal areas of extra-synaptic muscle membrane. After short-term denervation (up to 2.4 weeks) the extrajunctional binding increased, but there was no change in specific binding to the motor end-plate. Denervation for longer periods (up to 7 weeks) reduced binding sites at the end-plate by up to 60–70%. Direct electrical stimulation of these muscles for the entire period of denervation did not prevent the loss of junctional binding sites even though it was adequate to abolish the increase in extrajunctional toxin binding. In contrast, denervated end-plates on muscle fibres cross-innervated by a Foreign nerve at a distant location continued to bind normal amounts of toxin for over four months.     

Ultrastructural observations on muscle spindles in extraocular muscles of pig

Human and some mammals such as the sheep, goat and domestic and wild pigs have more or less muscle spindles in the extrinsic eye muscles, especially the domestic pigs having abundant muscle spindles (Matsuyama, 1987). The muscle spindles play a large role in maintaining the stable visual posture of the eyeballs. To define the morphological properties of the muscle spindles relative to the eye movement, the ultrastructure of the spindles was investigated in 6 extraocular muscles of the pigs by electron microscopy. The muscle spindles in the pig extraocular muscles consist of 4 to 5 intrafusal muscle fibers, one of which is nuclear bag fiber and 3 to 4 are nuclear chain fibers. The outer capsule is thin, composing of few layers, and the inner capsule ramifying to enwrap the individual fiber, accompanied by the medullated and unmedullated nerve fibers and blood capillaries. The nuclear bag fiber, 14 micron in diameter, is innervated by the atypical annulospiral sensory terminals and the chain fiber by the typical annulospiral terminal packed with mitochondria and microvesicles. The intrafusal fibers are innervated by the flower-spray sensory terminals anchoring deeply into the sarcoplasma, having abundant neurotubules and few mitochondria. The gamma motor end-plates have a relatively smooth synaptic cleft with a width of 70 nm and synaptic boutons containing few synaptic vesicles, sometimes, revealing a shallow fold of postsynaptic sarcolemma and abundant synaptic vesicles. The alpha motor end-plates reveal a relatively smooth synaptic cleft with a width of 80 nm, sometimes with a rough postsynaptic infolding, and boutons containing few synaptic vesicles and small-sized mitochondria. The satellite cells are innervated by the sensory terminals in various ways. The muscle spindles in the pig extraocular muscles are found to be much simpler in structure than those in the other antigravity muscles of the body. Their ultrastructure seems to reflect the morphological adaptation relative to the eyebal movement.     

Cholinergic receptors at denervated mammalian motor end-plates.

The number of acetylcholine receptors at normal and denervated end-plated in rat soleus muscles was studied using the binding of [125A] alpha-bungarotoxin as a quantitative assay. Normal end-plates bound several thousand times as much toxin as equal areas of extra-synaptic muscle membrane. After short-term denervation (up to 2.4 weeks) the extrajunctional binding increased, but there was no change in specific binding to the motor end-plate. Denervation for longer periods (up to 7 weeks) reduced binding sites at the end-plate by up to 60-70%. Direct electrical stimulation of these muscles for the entire period of denervation did not prevent the loss of junctional binding sites even though it was adequate to abolish the increase in extrajunctional toxin binding. In contrast, denervated end-plates on muscle fibres cross-innervated by a foreign nerve at a distant location continued to bind normal amounts of toxin for over four months.     

Structural differences of pale and strongly stained motor end-plates of the rat diaphragm

According to the staining intensities for AChE, the motor end-plates of the rat diaphragm can be classified into strong (S) and pale (P) types. About 34% of the total end-plates of the rat diaphragm are of S type and 50% of P type. The P end-plates differ from S end-plates in two aspects. First, the secondary subneural clefts of the S end-plates are well developed. They are numerous, long, closely packed and often branched. On the other hand, the secondary subneural clefts of the P end-plates are short, sparse and usually unbranched. Secondly, there seems to be a variation in AChE activity in the P end-plates. Focal negative AChE areas are found in the subneural apparatus of some P end-plates. It is concluded that the less well developed secondary subneural clefts and focal areas of negative AChE activity contribute to the paler staining of the P end-plates.     

神经肌蒂移植至环杓后肌的应用解剖

在21具成尸标本上,针对喉返神经损伤后的有关问题观察了支配舌骨下肌群和环甲肌的神经.从解剖学角度认为神经肌蒂移植时首选肩胛舌骨肌上腹肌支、胸骨舌骨肌上肌支或环甲肌肌支。暴露环(?)后肌的手术层次是咽下缩肌、咽肌、梨状隐窝和环(?)后肌筋膜。