人类腓肠肌外侧头的肌纤维型分布

本文试以亚部化的原则,按神经肌支在肌内的第一级分支分布的规律,将人体的腓肠肌外侧头分成三个亚部,并研究各亚部内两型肌纤维分布的特点和各亚部间纤维比例的差异。结果表明,腓肠肌外侧头的外侧浅、深二亚部之间在纤维型的比例方面没有明显差异,快缩纤维在男性占43.67%,在女性占33.68%。但是,在一例6岁男孩的内侧亚部中,发现其快缩纤维的比例显著增高,达63.25%。作者认为这是先天决定的,并假设内旋亚部可能是肌纤维型变异最多的部分,因此内侧亚部值得进一步研究。另一事实是在腓肠肌外侧头的原肌束内,快缩纤维在肌束的周缘部更为集中,与中央部相比,在统计学上有极显著的差异,这是腓肠肌外侧头肌纤维型分布的另一特征。     

小腿三头肌构筑学研究

对１６侧人小腿三头肌的肌构筑研究表明，腓肠肌内侧头的肌重和生物横切面积分别是外侧头的１．４６倍和１．６６倍，但肌纤维长仅后者的５／６。外侧头的肌质亚部，其肌纤维长／生理横切面积比率（１．９４）显著大于其他亚部。比目鱼肌的生理横切面积是腓肠肌的１．４倍，但肌纤维长／生理横切面积的比率仅及后者的１／４。这提示，腓肠肌两个头均属力量型肌，内侧头产生的张力大于外侧头，但外侧头缩短速度的潜力比内侧头高。比目     

家兔小腿三头肌亚部化研究

目的：探讨家兔小腿三头肌的亚部划分及该肌的功能。方法：Sihler肌内神经染色法；肌构筑法；肌纤维分型法。结果：从肌内神经的走行进一步证实兔腓肠肌外侧头3个亚部的假设。肌构筑研究显示腓肠肌外侧头慢行时以远端的中间亚部活动为主，快行时有近端的内、外侧亚部更多参与。肌球蛋白ATPase分型研究表明腓肠肌外侧头的3个亚部和腓肠肌内侧头均以ⅡB型纤维居多，比目鱼肌以Ⅰ型纤维占绝对优势。结论：Sihler染色法划分骨骼肌亚部更直观、可靠；腓肠肌外侧头外侧亚部以产生力量，内侧亚部以发挥速度为主；腓肠肌内侧头主要是维持膝在静力和动力状态下的稳定性；比目鱼肌的功能在兔表现不明显。     

人三角肌亚部化,肌纤维型分布及面积的研究

根据人三角肌的肌纤维起止、排列和神经支配特征,将该肌分为前、中、后3个亚部。用新鲜男性尸体标本16侧三角肌,按上述3个亚部的浅、深区分别取材,作恒冷箱冰冻横向切片,肌球蛋白ATP酶染色,将肌纤维分为Ⅰ型和Ⅱ型。检测各区的肌纤维型构成比例,并用图像分析仪测量各区两型肌纤维的横切面积和直径。结果发现,肌中部的I型纤维比例明显高于前、后两部,各亚部深区的I型纤维比例均比浅区高,而左、右侧之间无差异。各亚部及浅、深区。Ⅰ、Ⅱ型肌纤维的直径都相似(57～6lμm),仅中部深区Ⅱ型纤维直径(52.9μm)较其他各区肌纤维明显细小;除中部深区外,右侧两型纤维的直径均比左侧稍大,但统计学分析左右侧差异不显著。作者认为,三角肌纤维型分布的肌内差异,与该肌功能的分化密切相关。中部深区的Ⅰ型纤维比例较高,Ⅱ型纤维直径较细,可能提示该区的主要功能是维持肩关节稳定。     

骨骼肌横切面内肌纤维数量的间接计数法探讨

应用直接和间接计数肌纤维方法,计算人的右侧腓肠肌外侧头外侧浅亚部所含的肌纤维数量。在直接计数法中,将肌横切面行重叠连续照相,照片放大后,再拼接构成肌横切放大图。直接计算肌纤维总数及两型肌纤维的构成比。间接计数法以抽样摄取部分切面,再测量全部切片的横切面积,然后估算切片内肌纤维总数,并计数两型肌纤维的构成比。     

大鼠胸深肌肌纤维型的组成及分布

目的探讨SD大鼠胸深肌的肌纤维型组成和分布,借以了解该肌功能。方法采用Guth-Samaha肌球蛋白ATP酶组织化学染色法并稍做改良,对成年SD大鼠胸深肌冰冻切片进行肌纤维分型研究。结果大鼠胸深肌经肌球蛋白ATP酶组织化学染色后可明确分出2型肌纤维,即明亮色白的Ⅰ型纤维(慢缩纤维)和幽暗深褐的Ⅱ型纤维(快缩纤维),并且,两种纤维在肌内呈棋盘样均匀分布;图像分析仪下计数Ⅱ型纤维达到65%±6%,而Ⅰ纤维仅占35%±5%,前者明显高于后者(P<0.01)。结论大鼠胸深肌以Ⅱ型纤维为主,属于力量和速度型肌。     

大鼠腹外斜肌肌纤维型组成及分布研究

目的探讨大鼠腹外斜肌的肌纤维型组成和分布,借以了解该肌功能,并为运动训练模型的建立提供理论依据和研究平台。方法采用Guth-Samaha肌球蛋白ATP酶组织化学染色法并稍做改良,对成年SD大鼠腹外斜肌冰冻切片进行肌纤维分型研究。结果SD大鼠腹外斜肌经肌球蛋白ATP酶组织化学染色后可明确分出2型肌纤维,即明亮色白的Ⅰ型纤维(慢缩纤维)和幽暗深褐的Ⅱ型纤维(快缩纤维),并且,2种纤维在肌内呈棋盘样均匀分布;图像分析仪下计数Ⅱ型纤维达到(84.8±5.3)%,而Ⅰ纤维仅占(15.2±2.1)%,前者占绝对优势(P<0.01)。结论SD大鼠腹外斜肌以Ⅱ型纤维为主,除了起保护腹腔脏器作用外,还参与力量和速度运动。     

人四肢骨骼肌两型肌纤维的横切面积研究

目的 为查清人四肢骨骼肌两型肌纤维的横切面积和直径。方法 用死后２４ｈ内男性尸体５具（年龄２１￣２８岁）,分别取双侧上、下肢２９块肌共４８块肌组织,作恒冷箱冰冻横切片。以肌球蛋白ＡＴＰ酶组织化学染色（ｐＨ９．４）,将肌纤维分为Ｉ型和Ⅱ型。用网形测微尺测量两型肌纤维的横切面积和直径。结果 人四肢不同骨骼肌的肌纤维粗细各不相同,其平均横切面积范围在１７８０￣４７６０μｍ＾２之间,平均直径为４７．６￣７     

大鼠胸浅肌肌纤维型组成及其葡萄糖转运蛋白4表达特征

目的:研究大鼠胸浅肌不同肌纤维型的组成分布及其葡萄糖转运蛋白4(GLUT4)表达差异,了解该肌功能。方法:采用Guth-Samaha肌球蛋白ATP酶染色法并稍做改良,对成年SD大鼠胸浅肌冰冻切片进行肌纤维分型研究,并用免疫组织化学法对肌纤维分型后的切片进行GLUT4表达分析。结果:大鼠胸浅肌经肌球蛋白ATP酶染色后可明确分出明亮色白的Ⅰ型纤维和幽暗深褐的Ⅱ型纤维,2种纤维在肌内呈棋盘样均匀分布;Ⅰ型纤维比例为(52·6±6·3)%,Ⅱ纤维为(48·4±5·7)%,两者比例均等。免疫组织化学显色结果显示,GLUT4主要存在于包裹肌束的肌膜和Ⅰ型纤维膜上,而Ⅱ型纤维膜表达不明显。结论:大鼠胸浅肌两型纤维比例均等,属耐力兼速度型肌;Ⅰ型纤维膜的GLUT4表达高于Ⅱ型纤维,表明前者葡萄糖摄取能力高于后者。     

实验大鼠斜方肌肌纤维型组成及分布研究

目的探讨大鼠斜方肌的肌纤维型组成和分布,借以了解该肌功能。方法取成年SD大鼠斜方肌升部肌组织进行冰冻切片(8μm厚),采用Guth-Samaha肌球蛋白ATP酶组织化学染色法并稍做改良,对其进行肌纤维分型研究。结果SD大鼠斜方肌经肌球蛋白ATP酶组织化学染色后可明确分出2种肌纤维型,即白色的Ⅰ型纤维(慢缩纤维)和深褐色的Ⅱ型纤维(快缩纤维),2种肌纤维在肌内呈棋盘样均匀分布;图像分析计数其Ⅰ型纤维占(48.8±6.9)%,Ⅱ型纤维比例为(51.2±6.9)%,2者比较差异无统计学意义(P>0.05)。结论SD大鼠斜方肌2型肌纤维所占比例均等,与其维持颈背部姿势的作用一致。     

Nascent muscle fiber appearance in overloaded chicken slow-tonic muscle

The application of a weight overload to the humerus of chickens induces a hypertrophy of anterior latissimus dorsi (ALD) muscle fibers. This growth is accompanied by a rapid and almost complete replacement of one slow-tonic myosin isoform, SM-1, by another slow-tonic isoform, SM-2. In addition, a population of small fibers appears mainly in extrafascicular spaces and, concurrently, three additional myosin bands are detected by gel electrophoresis. Five antibodies against myosin heavy chain (MHC) isoforms were selected as immunocytochemical probes to determine the cellular location and nature of these myosins. The antibodies react with ventricular, fast skeletal muscle and either SM-1 or SM-2, or both the slow-tonic MHCs. The antifast and antiventricular antibodies react with myosin present in the 10-day embryonic ALD muscle but do not react with myosin in posthatch ALD muscle. The small fibers in overloaded muscle contain a myosin isoform characteristically expressed during the embryonic stage of ALD muscle development and therefore are named nascent myofibers. Some of the nascent myofibers do not react with the antibody to both slow-tonic MHCs, indicating the lack of the normal adult slow-tonic myosins which are expressed in 10-day embryos. In order to explore the origin of the nascent fibers, an electron microscopic study was performed. Stereological analysis of the existing fibers shows a stimulation of numbers and sizes of satellite cells. In addition, the volume occupied by nonmuscle and undifferentiated cells increases dramatically. Myotube formation with incipient myofibrils is seen in extrafascicular spaces. These data suggest that new muscle fiber formation accompanies hypertrophy in overloaded chicken ALD muscle, and the process may involve satellite cell migration.     

Non-neural and neural expression of myosin heavy chains by regenerated intrafusal fibers of rats.

Expression of myosin heavy chain (MHC) isoforms was studied in rat soleus (SOL) and extensor digitorum longus (EDL) muscles which regenerated in the presence or absence of innervation. Frozen sections of two 5 day denervated SOL and EDL grafts, two 40 day denervated SOL and EDL grafts, and two reinnervated 40 day SOL and EDL grafts were processed for demonstration of motor endplates, sensory endings, myosin adenosine triphosphatase (mATPase) and for expression of 4 MHCs. No qualitative differences in MHC expression were noted between 5 day or 40 day denervated grafts of the SOL and EDL muscles. All regenerated intrafusal and extrafusal myotubes or myofibers reacted to antibodies against neonatal and fast-twitch MHCs, but not to antibodies against slow-twitch and slow-tonic MHCs in these grafts. These data indicate that MHCs expressed by regenerated intrafusal myotubes do not parallel those expressed by myotubes which give rise to the three types of intrafusal fibers during development and that MHC expression by regenerated intrafusal myotubes parallels that of regenerated extrafusal myotubes prior to innervation. However, some regenerated intrafusal fibers in 40 day nerve-intact grafts bound antibodies to slow-twitch and slow-tonic MHCs, thus expressions of these two MHCs are nerve-dependent in regenerated muscle spindles.     

Limb myosin heavy chain isoproteins and muscle fiber types in the adult goat (Capra hircus)

The primary focus of this study was the accurate classification of limb skeletal muscle fiber types in adult goats (Capra hircus) according to the myosin heavy chain (MHC) isoform they express. Combined methodologies of gel electrophoresis, immunoblotting, immunohistochemistry, myofibrillar ATPase (mATPase), and quantitative metabolic enzyme histochemistry of M. semitendinosus samples were developed. Three MHCs were identified and tentatively designated as types I, IIA, and IIX. Five fiber types were defined immunohistochemically according to their MHC content: I, I+IIA, IIA, IIAX, and IIX. The hybrid fast-twitch fibers (IIAX) totaled 21% of the fiber population analyzed. The three major pure fibers (I, IIA, and IIX) could be objectively separated upon the basis of their mATPase activities after acid and alkaline preincubations. The prominent number of hybrid fibers, however, could not be delineated with these mATPase methods. Metabolic and size properties of muscle fibers varied according to their MHC content, but overlapped the full range of muscle fiber phenotypes. These integrated data demonstrate that type II skeletal muscle fibers of small ruminants have been misclassified in previous studies. The immunohistochemical approach developed in the present study offers new prospects for muscle fiber typing in caprine experimental studies and meat production technologies.     

Segmental Distribution of Myosin Heavy Chain Isoforms Within Single Muscle Fibers

Despite many studies looking at the distribution of myosin heavy chain (MHC) isoforms across a transverse section of muscle, knowledge of MHC distribution along the longitudinal axis of a single skeletal muscle fiber has been relatively overlooked. Immunocytochemistry was performed on serial sections of rat extensor digitorum longus (EDL) muscle to identify MHC types I, IIA, IIX, IIY, and IIB. Sixteen fascicles which contained a total of 362 fibers were randomly and systematically sampled from the three EDL muscles. All MHC type I and type II isoforms were expressed. Segmental expression occurred within a very limited segment. MHC isoform expression followed the accepted traditional order from I?IIA?IIX?IIB, however, in some samples expression of an isoform was circumvented from IIB to I or from I to IIB directly. Segmental distribution of MHC isoforms along a single muscle fiber may be because of the myonuclear domain. Anat Rec, 300:1636–1642, 2017. © 2017 Wiley Periodicals, Inc.     

Morphological,histochemical, and myosin isoform analysis of the diaphragm of adult horses,Equus caballus

The horse provides an interesting model for study of the structure and function of the mammalian diaphragm. Multiple regions of diaphragm from seven adult horses were prepared for histochemistry, immunocytochemistry, myosin heavy chain electrophoresis, and native myosin electrophoresis. Two additional adults were dissected to demonstrate myofiber and central tendon morphology and stained for acetylcholinesterase to demonstrate motor endplates. All regions of the adult diaphragm were histochemically characterized by a preponderance of type I fibers with some type IIa fibers. Type IIb fibers were absent in all adult specimens. Myosin heavy chain electrophoresis supported the histochemical study: two isoform bands were present on SDS gels that comigrated at the same rate as rat type I and IIa myosin heavy chain isoforms. No isoform was determined to comigrate with rat type IIb heavy chain isoforms. Native myosin isoform analysis revealed two isoforms that comigrated with rat FM-4 and FM-3 (FM = fast myosin) and two isoforms that comigrated with rat SM-1 and SM-2 (SM = slow myosin) isoforms. In some samples, a third slow native myosin isoform was observed that comigrated at the same rate as the SM-3 of the equine biceps brachii muscle. This doublet (or “triplet”) of slow isoforms is unique to some horse muscles compared with other adult animals studied. It is not known if these multiple slow native myosin isoforms confer some functional advantage to the equine muscles. The adult equine diaphragm also differs in its morphology by having a large central tendon compared to that in other mammals, and is predominantly slow in fiber type and myosin isoform composition. © 1994 Wiley-Liss, Inc.     

Myosin heavy and light chain expression during human skeletal muscle development and precocious muscle maturation induced by thyroid hormone

Summary It has now been well established that during mammalian muscle development there is a sequential transition of the myosin isoforms, with the developmental isoforms being replaced just before or just after birth by the adult isozymes. In a previous study of human fetal muscle, we demonstrated the differentiation of two fiber populations as early as 15 weeks: one population of large diameter fibers containing predominantly slow myosin heavy and light chains, and another population which stained homogeneously for fetal myosin heavy chain and corresponded to histochemical type IIC fibers. We have carried out an immunocytochemical and bio-chemical study of human fetal quadriceps between 7 and 40 weeks. A chronology of the changes which occur in the expression of the myosin heavy and light chains is correlated with the results obtained by enzyme histo-chemistry. Evidence is also presented that in man excessive amounts of thyroid hormone act directly on the muscle, and result in a precocious accumulation of the adult myosin heavy chains and a precocious maturation of the muscle.     

Heterogeneous postnatal transitions in myosin heavy chain isoforms within the rabbit temporalis muscle

Postnatal changes in the fiber type composition and fiber cross-sectional area were investigated in the superficial (TEM1) and deep (TEM23) temporalis of male rabbits. It was hypothesized that, due to the transition from suckling to chewing during early postnatal development, the proportion of fast fiber types would decrease, while the proportion of fibers positive for myosin heavy chain (MyHC) cardiac alpha would increase, and that, due to the influence of testosterone during late postnatal development, the proportion of these alpha fibers would decrease again. Classification of the fibers types was performed by immunohistochemistry according to their MyHC content. The proportion of alpha fiber types significantly increased in both muscle portions from 2% and 8% for TEM1 and TEM23 at week 1 to 29% and 54% at week 8, respectively,. While in TEM1 the proportion of this fiber type did not change thereafter, it decreased again to 27% in TEM23 at week 20. The change for the fast fiber types was opposite to that of the alpha fiber types. Significantly more MyHC IIX fibers were found in TEM1 than in TEM23 in adult rabbits. In the first 8 weeks, the cross-sectional areas of all fibers increased. After this period, only MyHC cardiac alpha + I fibers continued to increase significantly. It was concluded that there are developmental differences in the myosin heavy chain transitions of the two portions of the temporalis muscle.