Sarcoplasmic Masses Research Articles

An adult-onset myopathy characterized by a double ring appearance of muscle fibers

We report a 33-yr-old man with an unusual neuromuscular disorder characterized by progressive generalized weakness of 3 yr duration whose muscle biopsy showed a double ring appearance in most muscle fibers. This double ring appearance was due to a peripheral outer sarcoplasmic mass and an inner ring of annular myofibrils surrounding a core of normal longitudinally oriented myofibrils. Nerve conduction studies were normal. Electromyography showed fibrillations, positive waves, and increased brief duration, low amplitude, polyphasic potentials.

Skeletal muscle changes associated with equine myotonic dystrophy

A progressive neuromuscular disorder in young horses, clinically apparent as early as 1 month of age, is characterized by generalized myotonia, muscle stiffness, muscle weakness and atrophy. Myotonia is identified by percussion dimpling and myotonic EMG discharges. Changes in one case included testicular hypoplasia, cataract formation, and glucose intolerance, indicating a systemic involvement. Pathologic changes in skeletal muscles from three affected foals were examined. Sarcoplasmic masses, ringed fibers, internal positioning of sarcolemmal nuclei, and nuclear rowing were among the primary histologic changes noted. Variation in fiber diameter size, especially atrophy, and type I predominance were also prominent changes. A neurogenic involvement was indicated by type grouping changes in several muscles.

Desmin and actin associated with cytoplasmic bodies in skeletal muscle fibers: immunocytochemical and fine structural studies, with a note on unusual 18- to 20-nm filaments

In a fine structural and immunocytochemical study, the latter performed on semithin sections of epoxy resin embedded skeletal muscle fibers, three types of cytoplasmic bodies were identified in a case of cytoplasmic body myopathy: (1) The first type, the classical type, showed a central core and a light halo with radiating actin filaments at the periphery. (2) The second type, the spheroid body was characterized by irregularly arranged granular masses associated with intermediate filaments. Desmin immunoreactivity occurred in the central and peripheral parts, where filaments of intermediate size were visualized by electron microscopy. Desmin immunoreactivity was noted also at the Z-bands of striated annulets, within areas of disordered myofibrils, such as sarcoplasmic masses, and in atrophic muscle fibers. (3) The third type of the cytoplasmic body was composed mainly of large masses of uneven granularity and electron density. The center of this type reacted to anti-actin antibody suggesting that the 5- to 6-nm filaments, which ultrastructurally proved to be a major component, were of the actin type. By contrast, neither intermediate filaments nor actin microfilaments were found by electron microscopy in cytoplasmic bodies in a second case where no immunoreaction to desmin or actin occurred. Anti-vimentin antibody stained only the cytoplasm of endomysial cells, but not the inclusion bodies. Some other, unusual inclusions with 18- to 20-nm tubulo-filamentous structures have to be distinguished from the various types of filaments in cytoplasmic bodies. It is concluded, that pleomorphism and heterogeneity of "cytoplasmic bodies" have to be taken into consideration when classifying cytoplasmic body myopathies.

Ultrastructural changes in skeletal muscle in ovine muscular dystrophy.

The initial ultrastructural changes in skeletal myofibers in ovine muscular dystrophy (MD) consisted of focal degeneration of myofibrils and the formation of Z-disc abnormalities, including nemaline rods, in adjacent sarcomeres. Peripheral and central sarcoplasmic masses, which occurred initially in large diameter fibers, contained a mixture of normal organelles and abnormal tubular and fibrillar formations. Vesiculate sarcolemmal nuclei with prominent nucleoli accumulated in central and subsarcolemmal locations in small clusters and short rows. Deformed individual nuclei were sometimes present within nuclear rows. Loss of the myofibrillar mass, increased density of small spherical nuclei, collections of fibrillar and tubular arrays, excessive folding of the sarcolemma and greatly reduced fiber diameter were seen in the end stage of the dystrophic process. Resting satellite cells were present at all stages of lesion development. The morphological progression of the lesions suggested an inherited inability to effectively replace lost myofibrils with ultimate exhaustion of the capacity for repair followed by pathological fiber atrophy.

Skeletal muscle pathology in ovine congenital progressive muscular dystrophy. 1. Histopathology and histochemistry.

The histopathological lesions of ovine congenital progressive muscular dystrophy (CPMD) were characterized by myofiber hypertrophy, focal myofibrillar degeneration, formation of peripheral and central sarcoplasmic masses devoid of myofibrils and internal nuclei often in chains. Progressive loss of myofibrils was associated with atrophy of the fiber and eventual collapse of the sarcolemma. The process was polyphasic, consequently in mature lesions there was great variation in fiber diameter. Split fibers were common but ring fibers occurred rarely. Myofiber loss was associated with fatty or fibrous tissue replacement. Only type I (red, slow twitch, oxidative) fibers were affected and there was no histological evidence of effective regeneration. Ovine CPMD has many histopathological features in common with dystrophia myotonica in humans.

Neuromuscular plasticity following limb immobilization.

The effects of immobilization on the ultrastructure of the rat neuromuscular junction of type I and type II muscle fibres were studied both qualitatively and quantitatively. Muscle fibre areas were measured as well. The plantaris muscle was immobilized in a shortened position by applying a plaster cast for three weeks. Immobilized muscles were then compared to normal litter mates. Both type I and type II immobilized muscle fibres atrophied. Endplates from type II muscle fibres exhibited greater amounts of degeneration than type I endplates. Degeneration consisted of nerve terminal disruption, exposed junctional folds, postsynaptic areas which contained little or no postjunctional folds, and subjunctional sarcoplasmic masses. In addition to degeneration, the type II endplates also exhibited regeneration in the same endplate consisting of small terminals associated with large expanses of junctional folds, several small terminals occurring within the same primary synaptic cleft, and several axons wrapped by the same Schwann cell. These observations suggest terminal axonal regeneration. Our results demonstrate that limb immobilization produces muscle atrophy as well as denervation-like changes at the neuromuscular junctions which leads to terminal axonal sprouting and an ultrastructural remodelling.

Structural Alterations in Overacting Inferior Oblique Muscles

Primary and secondary overacting inferior oblique muscles were examined by light and electron microscopy and compared to normal inferior oblique muscles. The most conspicuous light microscopic difference between primary overacting and normal muscles was the presence of granular fibers in overacting muscles that contained sarcoplasmic masses. Some primary and secondary overacting muscles also contained fibers displaying increased vacuolization and atrophy. Other secondary overacting muscles showed only numerous fibers at various stages of atrophy. The affected fibers were distributed throughout the central and global regions of the posterior portion of the muscle. Electron microscopic examination showed aggregations of mitochondria and degenerating mitochondrial profiles. Longitudinal fiber splitting and activated satellite cells were associated with fibers displaying increased vacuolization. The results suggest that the primary overacting inferior oblique muscle is the result of a bilateral paresis of the superior oblique muscle.

HISTOCHEMICAL ANALYSES IN THE SOLEUS MUSCLE OF RATS TREATED WITH NEOSTIGMINE

Cholinesterase staining and Gomori's trichrome staining were performed in serial sections of soleus muscles of rats daily administered with 0.625mg/kg neostigmine for 2 or 3 weeks. In the affected muscle fibers, abnormally expanded subsarcolemmal sarcoplasmic masses were frequently observed with a homogenous greenish blue appearance by Gomori's trichrome staining. Cholinesterase activities were clearly demonstrated in serial sections at the areas corresponding to these sarcoplasmic masses.In teased fibers of the affected muscles, the areas adjacent to cholinesterase activities appeared enlarged and expanded.It is evident that there exists a close relationship between the sarcoplasmic mass and the motor endplate histochemically.

Histological and ultrastructural studies on the ringbands in human extraocular muscles

Ringbands are a typical finding in the extraocular muscles of individuals of twenty years and older. The number of these structures increases distinctly after the 60th year of life. In optimally fixed muscles the ringbands are separated from the sarcolemma by a space containing the so-called sarcoplasmic masses. These masses were composed of vaculated mitochondria, dilated tubules of the sarcoplasmic system and, in some fibers, of fragments of myofibrils. Structures from which a neoformation of myofibrils as the origin of the ringbands could be concluded (as proposed by Jonecko, 1967), were never observed in this hypolemmal area. In contrast, the formation of the ringbands seems to be correlated to the ultrastructural alterations of the myofilaments and the looser arrangement of the myofibrils which can first be observed in extraocular muscles of 10-year-old patients and increasingly in older patients (Mühlendyck, 1977). These alterations lead to continous and repeated changes in the orientation of the myofibrils during the extension and contraction processes of the muscle fiber. Thus, the myofibrils undergo a constant mechanical stress which they cannot resist indefinetly, leading to disruption of some of the fibrils. The disrupted free end contracts, deviates almost at a right angle from its former course and, while the sarcolemma forms thread-like folds during the contraction of the muscle fiber, it is coiled around the longitudinal undisrupted fibrillar core. This leads to a disfunction of the muscle fiber and aids in explaining the steady decrease of the excursion of the eye after about 30 years of age.

Core/targetoid fibres and multiple cytoplasmic bodies in organophosphate neuropathy

From correlated histochemical and ultrastructural investigations of biopsy specimens of a rare case with delayed-onset neuropathy due to organophosphate (Dipterex) intoxication, several pathological characteristics were recognized in the muscle fibres. Most striking was concurrence of core/targetoids and multiple cytoplasmic bodies in the same fibres. Foci of markedly reduced or absent oxidative enzyme activity were revealed in 71.6% of type I fibres and in 3.4% of type II fibres. Most of those foci were two-zoned core/targetoids. Cytoplasmic bodies were also revealed selectively in type I fibres contrary to the previous reports. Targets, targetoids, cores and multicores were suggested to be strongly related to each other pathogenetically and to be due to the disturbance of some neurotrophic influences. In the biopsy specimen taken 220 days after exposure to the drug, numerous sarcoplasmic masses were revealed, and they were very likely to represent special forms of regeneration.

Ringed fibres in skeletal muscles--a contribution to the statement of these structures in unselected obductions (author's transl)

26 muscles with one or more ringed fibres, corresponding to 2,83%, have been found in 939 muscles out of 313 unselected obductions. Taking into consideration that in the M. rectus femoris alone. 21 ringed fibres were found, raises the quota to 6.7%. After desintegration into primary diseases, the cardiovascular illnesses have been accompanied with ringed fibres in 20.6%, in comparison to the other disease groups which have been rarely or not at all affected. Apart from one case probably traumatic ringed fibres formation, individuals above 49 years old are exclusively striken, at which by far the male sex prevails. The number of ringed fibres continually increases with the age, and all cases with 20 or more ringed fibres have exceeded the 60th year. Besides there is also a relation between the ringed fibres frequency and the atrophy degree of the muscle. The fact that this relation is not reversible the presence of an additional dispositional factor must be concluded. The distribution pattern of the ringed fibres is non-uniform, they occur partly disseminated or also partly flock formed, heaped up ringed fibres. They are mostly simple closed circular fibres. Compound forms are sporadically observed. A coincidence of sarcoplasmic masses was in all cases not traceable. The information at hand will be discussed. The frequent appearance in cardiovascular illnesses leads back to stress factors like hypoxidosis, acidosis etc. by reduced cardiac output, the frequency in age to multifactor reasons. The preponderance of catabolic metabolism, electrolyte shifting and disturbances of transmineralisation is particularly made responsible. Etiological traumas play an additional role particularly in younger individuals. The frequent occurrence in the male sex is referred to the different gender-dependent gauge conditions of the two fibre types.

The light and electron microscopic changes in the skeletal muscles during paralysis in thyrotoxic periodic paralysis.

Light microscopy of the biopsied quadriceps muscles during paralysis in 17 patients with thyrotoxic periodic paralysis (TPP) showed no abnormalities in 23.5 per cent, sarcolemmal nuclear proliferation in 35.5 per cent, atrophy of muscle fibers in 29.4 per cent, central nuclei in 23.5 per cent, fatty infiltration in 17.6 per cent, vacuolation in 11.8 per cent, and sarcoplasmic masses in 11.8 per cent. The muscle specimens were also examined by electron microscopy in ten of these patients; the main changes observed were vacuolation (90 per cent), mitochondrial abnormalities (100 per cent), glycogen granules accumulation (100 per cent), disruption of the myofibers (50 per cent), and changes in the T-system (40 per cent). The light and electron microscopic changes in the skeletal muscles during paralysis were not well correlated with the severity of the muscle weakness of hypokalemia.

A myopathy associated with myotonia in the dog.

The pathology of two cases of canine myopathy associated with myotonia are presented. The changes were interpreted as dystrophic. The most obvious features were a rounding on cross section and variation in fibre size with numerous internal nuclei, many of which formed chains. Degeneration and regeneration were seen and there was a slight increase in perimysial and endomysial connective tissue. Only one ringed fibre was seen, but no sarcoplasmic masses. Enzyme histochemistry failed to demonstrate any selective Type I fibre atrophy. The peripheral and central nervous systems were normal in both cases.

Muscle and central nervous system metamorphosis. Histology and autoradiography.

In the tadpole and during the early metamorphotic stage of<i>Rana temporaria</i>, sarcoplasmic masses occur throughout the musculature. During the metamorphotic stage of<i>Xenopus laevis</i>, denervation features occur with (in lesser degree) sarcoplasmic masses or granular degeneration. Autoradiographic study in<i>X laevis</i>has revealed a blood-brain barrier in the tadpole to levothyroxine l 125, liothyronine I 125, sodium iodide 125, liothyronine 1131, and levothyroxine I 131. This barrier persists in the tail segment of the spinal cord during metamorphosis, but disappears for the brain and the trunk level of the cord. Similar observations were made with levothyroxine l 131 in<i>R temporaria</i>.

Variations in muscle status with age and systemic diseases.

The confusion and lack of histopathological information concerning the effects of ageing and selected systemic non-neuromuscular diseases on the muscle fiber have hampered overwhelmingly our understanding of muscular disease. In the superior recturs muscle sarcoplasmic masses akin to those seen in myotonic dystrophy appear early in adulthood and increase in size and number thereafter. Furthermore, it was found that with advancing age, there occurs in the skeletal muscles either a generalized decrease in muscle fiber diameter or a scattered or grouped atrophy of muscle fibers. The scattered muscle fiber atrophy seems to precede the grouped atrophy.

Early ultrastructural and biochemical changes in muscle in dystrophia myotonica

Muscle specimens from 8 patients with dystrophia myotonica at various stages of the disease have been studied. While the ultrastructural organization of the myofibrils appeared remarkably well-preserved, the sarcotubular system showed well-defined abnormalities which concerned mainly the sarcoplasmic reticulum and varied from discrete swelling to disorganization of the SR structures. The T-system was less severely involved. Longitudinal orientation, however, was found in all cases, while networks of proliferated T-tubules were observed in 1 case. The ultrastructural evidence also supported the view that sarcoplasmic masses are regenerative in nature. The data from studies of the calcium uptake activity of the microsomal fraction indicated that the decreased calcium uptake activity noted in advanced cases was probably due to the dystrophic process. The relevance of these changes to the dystrophic process and to the myotonic phenomenon is discussed.

A congenital progressive ovine muscular dystrophy.

A congenital progressive myopathy affecting 2% of a flock of Merino sheep involved most of the muscles of the pelvic and pectoral girdles. The vastus intermedius muscle was consistently affected; at 2 years of age 50% of its fibers were replaced by fat and at 5 years almost all. Lesions were bilaterally symmetrical. Usually all components of the quadriceps muscle were involved, but scattered affected fibers were found in most other appendicular muscles. The lesions in the quadriceps muscles resulted in inability to flex the femoro-tibial joint, with consequent difficulty in locomotion, which, under range conditions, resulted in death from inability to forage. Histologically, affected muscles had rounded fibers with central and peripheral sarcoplasmic masses. The fibers contained vesicular nuclei that usually formed rows of up to 15, but occasionally up to 50. In 6-week-old lambs, muscle fibers ranged in diameter from 15-100 μ. No lesion was detected in the peripheral or central nervous system.

Myopathy of the quadriceps muscles

A description is given of 2 brothers, aged 34 and 38 years respectively, who were both suffering from a very slowly progressive paresis and atrophy of the quadriceps muscles, with EMG changes indicative of a myopathy. Although the other muscles showed no signs of paresis, electromyographic examination did disclose myopathic changes elsewhere. Both patients showed creatinuria and increased serum creatine-phosphokinase activity. The muscle biopsy disclosed a variation in the diameter of muscle fibres, with increased fat and connective tissue and many ringed fibres and sarcoplasmic masses. The disease was interpreted as being a special form of muscular dystrophy.

A dystrophy-like myopathy in thyroidectomized rabbits

The histopathological and enzyme histochemical changes in the muscles of thyroidectomized rabbits are described. Between 4 and 18 months after thyroidectomy, the muscles were found to show changes reminiscent of muscular dystrophy, e.g. marked variation in fibre diameter, rounding of fibres, central migration of nuclei, vesicular nuclei with prominent nucleoli, sarcoplasmic masses and, in the later stages, a marked increase in connective tissue and a moderate increase in adipose tissue. Enzyme histochemical changes were also significant, both with oxidative and with glycogenolytic enzymes. Sarcoplasmic masses have been produced experimentally in the muscles of thyroidectomized rabbits.

The ultrastructural morphology of the muscle fiber in myotonic dystrophy

Biopsies from three patients with different clinical and pathological stages of myotonic dystrophy were studied by phase and electron microscopy. Large sarcoplasmic masses and spiral annulets were prominent in Cases 1 and 2 while in Case 3, featured clinically by atrophic weakness, they were infrequent. In the latter the residual fibers were either large and dystrophic or small and atrophic.