Histological features of endomysium,perimysium and epimysium in rat lateral pterygoid muscle

The distribution of the endomysium, perimysium, and epimysium and their constituent connective tissue fiber types in the mature rat lateral pterygoid muscle was examined with the light microscope. The endomysium and perimysium were relatively thin and consisted mainly of reticular fibers. The epimysium was thicker than the intramuscular sheaths and consisted of both collagen and reticular fibers; however, the thickness and constituent connective tissue fiber types of these sheaths varied regionally. Near the articular capsule and disc, the endomysium, perimysium, and epimysium were all thicker than in other regions of the muscle and consisted of collagen, reticular, and elastic fibers. The perimysium bound the bundles of muscle fibers together and frequently included blood vessels and nerves. As the superior head of the pterygoid muscle approached its insertion, sheaths of perimysium divided this head into smaller and smaller bundles of muscle fibers. In the inferior head, some of the perimysial sheaths and part of the epimysium were aponeurotic, and many muscle fibers attached to them. There were few such aponeurotic regions in the superior head. © 1996 Wiley-Liss, Inc.     

Analysis of fibronectin expression during human muscle differentiation

Fibronectin expression during human muscle differentiation was investigated by determining its distribution in foetal, normal adult and dystrophic muscle and in foetal, normal adult and dystrophic muscle cultures during myogenesis. Muscle sections and muscle cultures were studied by indirect immunofluorescence staining using polyclonal and monoclonal anti-human antibodies. Mass and clonal muscle cultures were prepared from foetal, adult and dystrophic muscle tissue. Immunofluorescence staining detected fibronectin on the epimysium, perimysium and endomysium of transverse sections of normal adult muscle, while sarcoplasm was devoid of this glycoprotein. In foetal muscle, some fibers showed a prominent ring of fibronectin. In mass and clonal cultures, myoblasts were found to synthesize and accumulate fibronectin while myotubes did not. No difference in fibronectin distribution was observed between Duchenne Muscular Dystrophy (DMD) and control myotubes. An enzyme-linked immunoassay (ELISA), performed on homogenated muscle, sonicated fibroblasts and muscle cells, showed a high fibronectin level in fibroblasts when compared with the other samples tested.     

The dynamics of compartmentalization of embryonic muscle by extracellular matrix molecules

In order to delineate the role of proteoglycans in muscle development, the immunohistological localization of glycosaminoglycans and proteoglycan core proteins was studied in embryonic chick leg at Hamburger-Hamilton stages (St.) 36, 39, 43, and 46, and at 2 weeks posthatching. A specific anatomical landmark was chosen (the junction between the pars pelvica and the pars accessoria of the flexor cruris lateralis muscle) in order to ensure the study of anatomically equivalent sites. Frozen cross sections were immunostained with monoclonal antibodies to chondroitin-4-sulfate, chondroitin-6-sulfate, dermatan sulfate, and keratan sulfate glycosaminoglycans; to the core proteins of muscle/mesenchymal chondroitin sulfate proteoglycan, dermatan sulfate proteoglycan, and basement membrane heparan sulfate proteoglycan; and to laminin and tenascin. Extracellular matrix zones corresponding to the endomysium, perimysium, epimysium, basement membrane, and myotendinous junction each show characteristic immunostaining patterns from St. 36 to St. 46 and have unique matrix compositions by St. 46. In some cases, there is a sequential or coordinate expression of epitopes, first in the epimysium, then the perimysium, and last in the endomysium. Dermatan sulfate proteoglycan is detected in the epimysium at St. 36, in the perimysium at St. 39 (there is no perimysium structure at St. 36), and is not detected in the endomysium until St. 43. A putative mesenchymal proteoglycan core protein (reactive to the monoclonal antibody MY-174) is detected at St. 39 in both epimysium and perimysium, but is not detected in the endomysium until St. 43. Keratan sulfate antibody immunostains epimysium at St. 39 and perimysium at St. 46, but is never detected in the endomysium. Some epitopes are expressed independently in each of the extracellular matrix zones: antibody to tenascin stains only a subset of the epimysium, at the myotendinous junction; and heparan sulfate proteoglycan and laminin are detected only in the endomysium. Between St. 36 and St. 39, the muscle/MY-174-reactive proteoglycan core protein staining decreases in intensity in the endomysium and becomes positive in the epimysium and perimysium. An inverse relationship is found between (1) the disappearance of muscle/MY-174-reactive proteoglycan core protein staining at the surface of myotubes from St. 36 to St. 39 and (2) the infiltration of laminin and heparan sulfate proteoglycan staining encompassing groups of myotubes (St. 36) to circumferential staining of all myotubes (St. 39).(ABSTRACT TRUNCATED AT 400 WORDS)     

Immunohistochemical localization of genetically distinct types of collagen in muscle of kuruma prawn Penaeus japonicus

• 1.1. The location of genetically distinct types of collagen in muscular tissue of the kuruma prawn was examined using immunohistochemical techniques.
• 2.2. Collagen was distributed not only in muscle connective tissues, which were classified into three forms, epimysium, perimysium and endomysium, but also in subcuticular membrane, which was mainly composed of two layers, hypodermis and subcuticular connective tissue.
• 3.3. The α1(Pr) component existed in all connective tissues in the kuruma prawn muscle. Type AR-II collagen was distributed in all the connective tissues except for the hypodermis, while the α2(Pr) component existed in the thin connective tissues, the perimysium and endomysium, and in the hypodermis.

     

Characterization of muscle epimysium, perimysium and endomysium collagens

In the past it has been proven difficult to separate and characterize collagen from muscle because of its relative paucity in this tissue. The present report presents a comprehensive methodology, combining methods previously described by McCollester [(1962) Biochim. Biophys. Acta 57, 427-437] and Laurent, Cockerill, McAnulty & Hastings [(1981) Anal. Biochem. 113, 301-312], in which the three major tracts of muscle connective tissue, the epimysium, perimysium and endomysium, may be prepared and separated from the bulk of muscle protein. Connective tissue thus prepared may be washed with salt and treated with pepsin to liberate soluble native collagen, or can be washed with sodium dodecyl sulphate to produce a very clean insoluble collagenous product. This latter type of preparation may be used for quantification of the ratio of the major genetic forms of collagen or for measurement of reducible cross-link content to give reproducible results. It was shown that both the epimysium and perimysium contain type I collagen as the major component and type III collagen as a minor component; perimysium also contained traces of type V collagen. The endomysium, the sheaths of individual muscle fibres, was shown to contain both type I and type III collagen as major components. Type V collagen was also present in small amounts, and type IV collagen, the collagenous component of basement membranes, was purified from endomysial preparations. This is the first biochemical demonstration of the presence of type IV collagen in muscle endomysium. The preparation was shown to be very similar to other type IV collagens from other basement membranes on sodium dodecyl sulphate/polyacrylamide-gel electrophoresis and was indistinguishable from EHS sarcoma collagen and placenta type IV collagen in the electron microscope after rotary shadowing.     

Protocol for rat single muscle fiber isolation and culture

To attain a superior in vitro model of mature muscle fibers, we modified the established protocol for isolating single muscle fibers from rat skeletal muscle. Muscle fiber cultures with high viability were obtained using flexor digitorum brevis muscle and lasted for at least 7 days. We compared the expression levels of adult myosin heavy chain (MyHC) isoforms in these single muscle fibers with myotubes formed from myoblasts; isolated fibers contained markedly more abundant adult MyHC isoforms than myotubes. This muscle fiber model, therefore, will be useful for studying the various functions and cellular processes of mature muscles in vitro.     

Developmental expression of extracellular matrix components in intramuscular connective tissue of bovine semitendinosus muscle

 We have investigated the expression patterns of extracellular matrix components in intramuscular connective tissue during the development of bovine semitendinosus muscle by means of indirect immunofluorescence techniques. Types I, III, V, and VI collagen and fibronectin were located in the endomysium and the perimysium. Type IV collagen, laminin, and heparan sulfate proteoglycans (PGs) were exclusively located in the endomysium, and dermatan sulfate PGs existed only in the perimysium. The localization of these components in the intramuscular connective tissue of semitendinosus muscle remained unchanged throughout prenatal and postnatal growth of cattle, suggesting that they are essential for forming and maintaining structures of the endomysium and perimysium in bovine semitendinosus muscle. On the other hand, decorin was undetectable in the endomysium of neonates, although other matrix components were already expressed. It was expressed slightly in the endomysium of 2-month-old calves, and clearly detectable in the endomysium of cattle more than 6 months old. Chondroitin sulfate PGs were barely detectable in the perimysium of fetuses and neonatal calves, and progressively appeared during postnatal development of the muscle. It seems likely that these PGs are closely related to the postnatal development of the endomysium and perimysium. Accepted: 30 October 1996     

Localization of hyaluronan in various muscular tissues

Summary The histochemical distribution of hyaluronan (hyaluronic acid, HYA) was analysed in various types of muscles in the rat by use of a hyaluronan-binding protein (HABP) and the avidin-biotin/peroxidase complex staining procedure. Microwave-aided fixation was used to retain the extracellular location of the glycosaminoglycan. In skeletal muscles, HYA was detected in the connective tissue sheath surrounding the muscles (epimysium), in the septa subdividing the muscle fibre bundles (perimysium) and in the connective tissue surrounding each muscle fibre (endomysium). HYA was heterogeneously distributed in all striated muscles. In skeletal muscles with small fibre dimensions (e.g., the lateral rectus muscle of the eye and the middle ear muscles), HYA was predominantly accumulated around the individual muscle fibres. Perivascular and perineural connective tissue formations were distinctly HYA-positive. In cardiac muscles, HYA was randomly distributed around the branching and interconnecting muscle fibres. In comparison, smooth muscle tissue was devoid of HYA.     

Diversity of extracellular matrix morphology in vertebrate skeletal muscle

Existing data suggest the extracellular matrix (ECM) of vertebrate skeletal muscle consists of several morphologically distinct layers: an endomysium, perimysium, and epimysium surrounding muscle fibers, fascicles, and whole muscles, respectively. These ECM layers are hypothesized to serve important functional roles within muscle, influencing passive mechanics, providing avenues for force transmission, and influencing dynamic shape changes during contraction. The morphology of the skeletal muscle ECM is well described in mammals and birds; however, ECM morphology in other vertebrate groups including amphibians, fish, and reptiles remains largely unexamined. It remains unclear whether a multilayered ECM is a common feature of vertebrate skeletal muscle, and whether functional roles attributed to the ECM should be considered in mechanical analyses of non-mammalian and non-avian muscle. To explore the prevalence of a multilayered ECM, we used a cell maceration and scanning electron microscopy technique to visualize the organization of ECM collagen in muscle from six vertebrates: bullfrogs (Lithobates catesbeianus), turkeys (Meleagris gallopavo), alligators (Alligator mississippiensis), cane toads (Rhinella marina), laboratory mice (Mus musculus), and carp (Cyprinus carpio). All muscles studied contained a collagen-reinforced ECM with multiple morphologically distinct layers. An endomysium surrounding muscle fibers was apparent in all samples. A perimysium surrounding groups of muscle fibers was apparent in all but carp epaxial muscle; a muscle anatomically, functionally, and phylogenetically distinct from the others studied. An epimysium was apparent in all samples taken at the muscle periphery. These findings show that a multilayered ECM is a common feature of vertebrate muscle and suggest that a functionally relevant ECM should be considered in mechanical models of vertebrate muscle generally. It remains unclear whether cross-species variations in ECM architecture are the result of phylogenetic, anatomical, or functional differences, but understanding the influence of such variation on muscle mechanics may prove a fruitful area for future research.     

Morphology of connective tissue in skeletal muscle

The arrangement and distribution of connective tissue in six different skeletal muscles and smooth muscle was examined by scanning electron microscopy. The endomysial arrangement of collagen was similar in all types of muscle and consisted of three components: (1) myocyte-myocyte connectives; (2) myocyte-capillary connectives; and (3) a weave network of collagen intimately associated with the basal laminae of the myocytes. The perimysium of the different muscles was qualitatively similar but quantitatively dissimilar. The perimysium consisted of large tendon-like bundles of interwoven collagen which connected with the dense weave collagen that surrounded groups of muscles. The arrangement of the collagen in the perimysium and endomysium would explain differences in the mechanical properties of the different muscle. The contribution of the connective tissue to mechanical properties of muscle is discussed.     

Chick myotendinous antigen. I. A monoclonal antibody as a marker for tendon and muscle morphogenesis

Extracellular matrix components are likely to be involved in the interaction of muscle with nonmuscle cells during morphogenesis and in adult skeletal muscle. With the aim of identifying relevant molecules, we generated monoclonal antibodies that react with the endomysium, i.e., the extracellular matrix on the surface of single muscle fibers. Antibody M1, which is described here, specifically labeled the endomysium of chick anterior latissimus dorsi muscle (but neither the perimysium nor, with the exception of blood vessels and perineurium, the epimysium ). Endomysium labeling was restricted to proximal and distal portions of muscle fibers near their insertion points to tendon, but absent from medial regions of the muscle. Myotendinous junctions and tendon fascicles were intensely labeled by M1 antibody. In chick embryos, " myotendinous antigen" (as we tentatively call the epitope recognized by M1 antibody) appeared first in the perichondrium of vertebrae and limb cartilage elements, from where it gradually extended to the premuscle masses. Around day 6, tendon primordia were clearly labeled. The other structures labeled by M1 antibody in chick embryos were developing smooth muscle tissues, especially aorta, gizzard, and lung buds. In general, tissues labeled with M1 antibody appeared to be a subset of the ones accumulating fibronectin. In cell cultures, M1 antibody binds to fuzzy, fibrillar material on the substrate and cell surfaces of living fibroblast and myogenic cells, which confirms an extracellular location of the antigenic site. The appearance of myotendinous antigen during limb morphogenesis and its distribution in adult muscle and tendon are compatible with the idea that it might be involved in attaching muscle fibers to tendon fascicles. Its biochemical characterization is described in the accompanying paper ( Chiquet , M., and D. Fambrough , 1984, J. Cell Biol. 98:1937-1946).     

Metabolism of myosin heavy chain in steady-state chick skeletal muscle cultures.

Synthesis, accumulation and breakdown of the 200000-mol.wt. heavy subunit of myosin were analysed over an 11 day period in muscle cell cultures isolated from the leg muscle of 12-day chick embryos. Muscle cells accumulated myosin heavy chain rapidly from days 2 to 5 and maintained a maximum, constant myosin-heavy-chain concentration between days 7 and 11. Myosin-heavy-chain content and breakdown rate were compared in steady-state muscle cultures grown either in the presence of an optimum batch of horse serum (control) or in the presence of horse serum that had been pre-selected for its ability to inhibit several-fold the rate of synthesis of myosin heavy chain (inhibitory). The quantity of myosin heavy chain in the inhibited cultures was decreased in direct proportion to the decrease in the rate of synthesis of myosin heavy chain; however, the half-lives of myosin heavy chain (control, 17.7h; inhibitory, 17.0h) were virtually identical. In contrast, the absolute rate of breakdown of myosin heavy chain, expressed as molecules/min per nucleus, was approx. 5-fold lower in the inhibited cultures (4.3 X 10(3) molecules/min per nucleus) than in the control cultures (21.7 X 10(3) molecules/min per nucleus). Thus, inhibition of myosin-heavy-chain synthesis in this case was accompanied by diminished myosin-heavy-chain concentration and absolute breakdown rate at the altered steady state, but relative myosin-heavy-chain breakdown rates were unchanged.     

Slow and fast myosin heavy chain content defines three types of myotubes in early muscle cell cultures

We prepared monoclonal antibodies specific for fast or slow classes of myosin heavy chain isoforms in the chicken and used them to probe myosin expression in cultures of myotubes derived from embryonic chicken myoblasts. Myosin heavy chain expression was assayed by gel electrophoresis and immunoblotting of extracted myosin and by immunostaining of cultures of myotubes. Myotubes that formed from embryonic day 5-6 pectoral myoblasts synthesized both a fast and a slow class of myosin heavy chain, which were electrophoretically and immunologically distinct, but only the fast class of myosin heavy chain was synthesized by myotubes that formed in cultures of embryonic day 8 or older myoblasts. Furthermore, three types of myotubes formed in cultures of embryonic day 5-6 myoblasts: one that contained only a fast myosin heavy chain, a second that contained only a slow myosin heavy chain, and a third that contained both a fast and a slow heavy chain. Myotubes that formed in cultures of embryonic day 8 or older myoblasts, however, were of a single type that synthesized only a fast class of myosin heavy chain. Regardless of whether myoblasts from embryonic day 6 pectoral muscle were cultured alone or mixed with an equal number of myoblasts from embryonic day 12 muscle, the number of myotubes that formed and contained a slow class of myosin was the same. These results demonstrate that the slow class of myosin heavy chain can be synthesized by myotubes formed in cell culture, and that three types of myotubes form in culture from pectoral muscle myoblasts that are isolated early in development, but only one type of myotube forms from older myoblasts; and they suggest that muscle fiber formation probably depends upon different populations of myoblasts that co-exist and remain distinct during myogenesis.     

Expression of myosin heavy chain isoforms in regenerating myotubes of innervated and denervated chicken pectoral muscle

Monoclonal antibodies were prepared to stage-specific chicken pectoral muscle myosin heavy chain isoforms. From comparison of serial sections reacted with these antibodies, the myosin heavy chain isoform composition of individual myofibers was determined in denervated pectoral muscle and in regenerating myotubes that developed following cold injury of normal and denervated muscle. It was found that the neonatal myosin heavy chain reappeared in most myofibers following denervation of the pectoral muscle. Regenerating myotubes in both innervated and denervated muscle expressed all of the myosin heavy chain isoforms which have thus far been characterized in developing pectoral muscle. However, the neonatal and adult myosin heavy chains appeared more rapidly in regenerating myotubes compared to myofibers in developing muscle. While the initial expression of these isoforms in the regenerating areas was similar in innervated and denervated muscles, the neonatal myosin heavy chain did not disappear from noninnervated regenerating fibers. These results indicate that innervation is not required for the appearance of fast myosin heavy chain isoforms, but that the nerve plays some role in the repression of the neonatal myosin heavy chain.     

Developmental appearance of myosin heavy and light chain isoforms in vivo and in vitro in chicken skeletal muscle

Three myosin heavy chain isoforms with unique peptide maps appear sequentially in the development of the chicken pectoralis major muscle. An embryonic isoform is expressed early and throughout development in the embryo. A second isoform appears just after hatching and predominates by 10 days ex ovo. A third isoform, indistinguishable from adult myosin heavy chain, predominates by 8 weeks after hatching. This sequence of myosin isoform change does not, however, appear during myogenesis in vitro. In cultures prepared from embryonic myoblasts only embryonic myosin heavy chain is expressed. This is true even in cultures maintained for 30 days. Myosin light chain expression also changes in vivo with a progressive increase in fast light chain 3 accumulation. In vitro, however, this shift to increasing fast light chain 3 accumulation does not occur. The results indicate that the myosin heavy chain and light chain pattern observed in vitro is identical to that of the embryonic muscle and that the conditions necessary for the shift in expression to a more mature myosin phenotype are not present in myogenic cultures. These cultures are therefore potentially of great value in probing further the neural and humoral determinants of muscle fiber maturation and growth.     

The effect of neonatal deafferentation or deefferentation on myosin heavy chain expression in intrafusal muscle fibers of the rat

Summary Muscle spindles were either deafferented or deefferented by selectively severing the sensory or motor nerve supply to neonatal soleus muscles of rats at a time when spindles are formed but when intrafusal muscle fibers are structurally and immunocytochemically immature. Experimental muscles wereexcised two months after nerve section. Control and experimental spindles were examined using monoclonal antibodies specific for myosin heavy chains of slow-tonic (ALD58) and fast-twitch (MF30) chicken muscles. Only intrafusal fibers bound these antibodies in intact soleus muscles. The deefferented spindles exhibited a pattern of ALD58 and MF30 binding similar to that of normal adult intrafusal fibers, whereas deafferented intrafusal fibers were unreactive with the two antibodies. Thus intact sensory innervation is essential for myosin heavy chain expression in intrafusal muscle fibers during postnatal development of rat spindles.     

The effect of neonatal deafferentation or defferentation on myosin heavy chain expression in intrafusal muscle fibers of the rat

Muscle spindles were either deafferented or deefferented by selectively severing the sensory or motor nerve supply to neonatal soleus muscles of rats at a time when spindles are formed but when intrafusal muscle fibers are structurally and immunocytochemically immature. Experimental muscles were excised two months after nerve section. Control and experimental spindles were examined using monoclonal antibodies specific for myosin heavy chains of slow-tonic (ALD58) and fast-twitch (MF30) chicken muscles. Only intrafusal fibers bound these antibodies in intact soleus muscles. The deefferented spindles exhibited a pattern of ALD58 and MF30 binding similar to that of normal adult intrafusal fibers, whereas deafferented intrafusal fibers were unreactive with the two antibodies. Thus intact sensory innervation is essential for myosin heavy chain expression in intrafusal muscle fibers during postnatal development of rat spindles.     

Myosin heavy chain isoforms in postnatal muscle development of mice

In this study, using a high-resolution gel electrophoresis technique, we have characterized the myosin heavy chain composition in different skeletal muscle of the mouse during postnatal development. The pattern of myosin heavy chain expression was studied in four hind limb muscles, the diaphragm, the tongue and the masseter. All of these muscles displayed the usual sequential transitions from embryonic to neonatal and to adult myosin heavy chain isoforms but more interestingly these transitions occur with a distinct chronology in the different muscles. In addition, our results demonstrated a transitory pattern of expression for certain adult myosin heavy chain isoforms in the soleus and the tongue. In the soleus muscle IIB and in the tongue IIA myosin heavy chain isoforms were detected only for a short time during postnatal life. Our results demonstrate that muscles of the mouse with different functions are subjected to a distinct programs of myosin isoform transitions during postnatal muscle development. This study describes new data which will help us to understand both postnatal muscle development in transgenic mouse muscles as well as in muscle pathology.     

Myosin heavy-chain isoforms in human smooth muscle

The myosin heavy-chain composition of human smooth muscle has been investigated by sodium dodecyl sulfate/polyacrylamide gel electrophoresis, enzyme immunoassay, and enzyme-immunoblotting procedures. A polyclonal and a monoclonal antibody specific for smooth muscle myosin heavy chains were used in this study. The two antibodies were unreactive with sarcomeric myosin heavy chains and with platelet myosin heavy chain on enzyme immunoassay and immunoblots, and stained smooth muscle cells but not non-muscle cells in cryosections and cultures processed for indirect immunofluorescence. Two myosin heavy-chain isoforms, designated MHC-1 and MHC-2 (205 kDa and 200 kDa, respectively) were reactive with both antibodies on immunoblots of pyrophosphate extracts from different smooth muscles (arteries, veins, intestinal wall, myometrium) electrophoresed in 4% polyacrylamide gels. In the pulmonary artery, a third myosin heavy-chain isoform (MHC-3, 190 kDa) electrophoretically and antigenically distinguishable from human platelet myosin heavy chain, was specifically recognized by the monoclonal antibody. Analysis of muscle samples, directly solubilized in a sodium dodecyl sulfate solution, and degradation experiments performed on pyrophosphate extracts ruled out the possibility that MHC-3 is a proteolytic artefact. Polypeptides of identical electrophoretic mobility were also present in the other smooth muscle preparations, but were unreactive with this antibody. The presence of three myosin heavy-chain isoforms in the pulmonary artery may be related to the unique physiological properties displayed by the smooth muscle of this artery.