Intermuscular Connective Tissue Research Articles

Microscopic changes in experimentally damaged rabbit muscles under the influence of transplanted mesenchymal stem cells

The relevance of the work is related to the possibility of artificially adjusting the intensity of skeletal muscle tissue regeneration in animals, which will significantly affect the tactics of rehabilitation treatment of muscle injuries in the future. The purpose of the research was to determine the effectiveness of the transplanted mesenchymal stem cells on the recovery processes in experimentally injured rabbit muscles. The method of histological examination of microscopic changes in the experimentally damaged muscle tissue of the pelvic head of the biceps femoris muscle of rabbits was used. Microscopic studies of the regeneration process of experimentally damaged striated muscle tissue established that in animals after intramuscular injection of allogeneic mesenchymal stem cells, connective tissue developed around the defect on day 2 of the experiment. On day 4, a large number of stem cells were detected in the connective tissue at the site of muscle tissue damage. On day 6, only relatively small foci of muscle tissue regeneration were observed in this area. On day 8, only small focal accumulations of stem cells were detected in this location. On the 10th day after intramuscular injection of mesenchymal stem cells, newly developed muscle fibres appeared at the site of injury. On the 14th day after intramuscular injection of mesenchymal stem cells, fully developed muscle fibres and intermuscular connective tissue were observed at the site of injury. In rabbits, after intramuscular injection of allogeneic mesenchymal stem cells, all regenerative processes were more active than in animals of other experimental groups and were completely completed by day 14 of the experiment. The practical value of the results obtained is to clarify the patterns of development of reparative processes in the damaged muscle area and to determine the effectiveness of using transplanted allogeneic mesenchymal stem cells in stimulating recovery processes, which is important to consider in the treatment of muscle injuries using regenerative therapy

Longitudinal Changes in MRI Muscle Morphometry and Composition in People With Inclusion Body Myositis.

Limited data suggest that quantitative MRI (qMRI) measures have potential to be used as trial outcome measures in sporadic inclusion body myositis (sIBM) and as a noninvasive assessment tool to study sIBM muscle pathologic processes. Our aim was to evaluate changes in muscle structure and composition using a comprehensive multiparameter set of qMRI measures and to assess construct validity and responsiveness of qMRI measures in people with sIBM. This was a prospective observational cohort study with assessments at baseline (n = 30) and 1 year (n = 26). qMRI assessments include thigh muscle volume (TMV), inter/intramuscular adipose tissue (IMAT), muscle fat fraction (FF), muscle inflammation (T2 relaxation time), IMAT from T2* relaxation (T2*-IMAT), intermuscular connective tissue from T2* relaxation (T2*-IMCT), and muscle macromolecular structure from the magnetization transfer ratio (MTR). Physical performance assessments include sIBM Physical Functioning Assessment (sIFA), 6-minute walk distance, and quantitative muscle testing of the quadriceps. Correlations were assessed using the Spearman correlation coefficient. Responsiveness was assessed using the standardized response mean (SRM). After 1 year, we observed a reduction in TMV (6.8%, p < 0.001) and muscle T2 (6.7%, p = 0.035), an increase in IMAT (9.7%, p < 0.001), FF (11.2%, p = 0.030), connective tissue (22%, p = 0.995), and T2*-IMAT (24%, p < 0.001), and alteration in muscle macromolecular structure (ΔMTR = -26%, p = 0.002). A decrease in muscle T2 correlated with an increase in T2*-IMAT (r = -0.47, p = 0.008). Deposition of connective tissue and IMAT correlated with deterioration in sIFA (r = 0.38, p = 0.032; r = 0.34, p = 0.048; respectively), whereas a decrease in TMV correlated with a decrease in quantitative muscle testing (r = 0.36, p = 0.035). The most responsive qMRI measures were T2*-IMAT (SRM = 1.50), TMV (SRM = -1.23), IMAT (SRM = 1.20), MTR (SRM = -0.83), and T2 relaxation time (SRM = -0.65). Progressive deterioration in muscle quality measured by qMRI is associated with a decline in physical performance. Inflammation may play a role in triggering fat infiltration into muscle. qMRI provides valid and responsive measures that might prove valuable in sIBM experimental trials and assessment of muscle pathologic processes. This study provides Class I evidence that qMRI outcome measures are associated with physical performance measures in patients with sIBM.

Supplementary studies on Myxobolus talievi Dogiel, 1957 (Cnidaria, Myxozoa) from the skeletal muscle of the cottoid fish Cyphocottus eurystomus in Lake Baikal: Morphological, histological and molecular characterisations.

Myxobolus talievi Dogiel, 1957 was originally described from the eyes, skeletal muscles and body cavity of endemic cottoid fish from Lake Baikal. In the present study, we supply new information on the myxospore morphology and histopathology of M. talievi; furthermore, we complete the original species description by Dogiel and Bogolepova (1957) with 18S ribosomal DNA (rDNA) sequence data. Histopathological analysis showed that the plasmodium was encapsulated by a thin layer of connective tissue and located in the intermuscular connective tissue among muscle cells. No inflammation was observed. Phylogenetic analysis revealed that M. talievi clustered with Myxobolus sp. 2 (NCBI Acc. No. U13830), an unidentified Myxobolus species from cottoid fish studied by Smothers et al. (1994), and located in the sister clade of Myxobolus spp. developing spores in the nerves of salmonids.

Heart damage in the combined types of systemic amyloidosis

To identify and determine the clinical and morphological characteristics of combined types of SA in patients with biventricular chronic heart failure (CHF). Eighty autopsy protocols for biventricular CHF deaths were retrospectively analyzed. Immunohistochemistry and confocal laser scanning microscopy (CLCM) with antibodies to amyloid A (AA), serum amyloid-P (SAP), prealbumin, and immunoglobulin kappa (κ) and lambda (λ) light chains were performed. The myocardium showed a combination of different types of SA in 6 (7.5%) cases, including Alλ-CA+ATTR-CA, ALκ-CA+ATTR-CA, and AA-CA+ATTR-CA in 4, 1, and 1 cases, respectively. Macroscopically, the heart mass averaged 470±20 g; the thickness of the left and right ventricular myocardium was 1.5±0.2 and 0.4±0.1 cm, respectively; the interventricular septum averaged 1.2±0.2 cm; and the cardiac index was 0.008. The myocardium was dense, dark red with diffuse layers of whitish dense fibrous connective tissue; the heart cavities were enlarged. Microscopically, in 25% of cases, all heart parts had ALλ-CA that was characterized by massive amyloid deposits localized predominantly in the intramyocardial vessel wall, intermuscular connective tissue, and perivascularly. The myocardium also displayed small amyloid deposits of ALλ-CA and ATTR-CA in the intermuscular connective tissue and intramyocardial vessel wall. Amyloid deposits were located in different parts of the myocardium; there were also areas of co-localization of ALλ-CA+ATTR-CA. The combined types of SA occurred under the guise of coronary heart disease and the dilated cardiomyopathy phenotype. The combined amyloid AL-CA and ATTR-CA was generally localized in the interstitium and myocardial vessels. There were also small areas of co-localization of amyloid deposits, which were found mainly in the intramyocardial vessels.

ИДЕНТИФИКАЦИЯ ВОЗБУДИТЕЛЕЙ ЗООНОЗОВ У КАБАНА (SUS SCROFA, LINNAEUS, 1758) ПРИ ВЕТЕРИНАРНО-САНИТАРНОЙ ЭКСПЕРТИЗЕ ПРОДУКТОВ УБОЯ

The paper presents the results of a veterinary and sanitary study of meat and offal of wild boar (Sus scrofa). According to the results of our study, adult boars were infected with helminths, which are dangerous for humans: in two boars (14,3%) plerocercoids Spirometra sp. (sparganum) were found in the intermuscular connective tissue, in two samples (14,3%) microcysts of protozoa Sarcocystis sp. were detected, in one sample (7,1%) a large number of nematodes of the genus Metastrongylus were found in the lungs. Trichinosis, cysticercosis, echinococcosis, fascioliasis were not registered by us in the presented material.

Histologic Evaluation of Nonvisual Afferent Sensory Upper Eyelid Proprioception.

Recent research has suggested a possible role for proprioception in ipsilateral frontalis activation in the setting of ptosis; however, there has not been any robust histologic or anatomic evidence to support this theory. To further elucidate proprioceptive structures in the eyelid, this investigation uses validated histologic techniques to explore the presence of proprioceptive structures or afferent neural networks in the Levator Palpebrae Superioris (LPS) and Müller muscle. Müller muscle and LPS samples were evaluated by a laboratory with extensive experience with the histology of extraocular muscle proprioception. Immunofluorescence and confocal laser scanning microscopy were used to analyze the tissue samples. Thirty-four Müller muscle samples and 10 LPS samples were analyzed. Golgi tendon bodies and muscle spindles were not identified in the Müller muscle and LPS samples. This result is expected in the Müller muscle given that these structures are not typically present in smooth muscle, but noteworthy in the skeletal muscle of the LPS. Previously undescribed synaptophysin-positive free nerve terminals within the intermuscular connective tissue of the Müller muscle were identified. The nerve terminals identified are anatomically consistent with free nerve endings present in the extraocular muscles that have been implicated in proprioception. These findings advance our current knowledge of the ultrastructure of Müller muscle and the LPS and suggest a possible mechanism for proprioception in the upper eyelid that may have a role in ipsilateral brow elevation in the setting of ptosis.The authors describe proprioception in the upper eyelid: A histologic analysis.

Myofascial Loads Can Occur without Fascicle Length Changes.

Many studies have shown that connective tissue linkages can transmit force between synergistic muscles and that such force transmission depends on the position of these muscles relative to each other and on properties of their intermuscular connective tissues. Moving neighboring muscles has been reported to cause longitudinal deformations within passive muscles held at a constant muscle-tendon unit (MTU) length (e.g., soleus [SO]), but muscle forces were not directly measured. Deformations do not provide a direct measure of the force transmitted between muscles. We combined two different muscle preparations to assess whether myofascial loads exerted by neighboring muscles result in length changes of SO fascicles. We investigated the effects of proximal MTU length changes of two-joint gastrocnemius (GA) and plantaris (PL) muscles on the fascicle length of the one-joint SO muscle within (1) an intact muscle compartment and (2) a disrupted compartment that allowed measurements of fascicle length and distal tendon force of SO simultaneously. SO muscle bellies of Wistar rats (n = 5) were implanted with sonomicrometry crystals. In three animals, connectivity between SO and GA+PL was enhanced. Measurements were performed before and during maximal excitation of all plantar flexor muscles. In both setups, MTU length of GA+PL did not affect the length of SO fascicles, neither during passive nor active conditions. However, lengthening the MTU of GA+PL increased distal tendon force of SO by 43.3-97.8% (P < 0.001) and 27.5-182.6% (P < 0.001), respectively. This indicates that substantial myofascial force transmission between SO and synergistic muscle can occur via a connective tissue network running parallel to the series of SO sarcomeres without substantial length changes of SO fascicles.

Clinical Aspects and Cellular Mechanisms of Fascia, their Interactions, and Importance in Medicine

The fascial system is a 3D continuum of soft, collagen‐containing, loose and dense fibrous connective tissues, widely including adipose tissue, adventitiae and neurovascular sheaths, aponeuroses, deep and superficial fasciae, epineurium, membranes, joint capsules, ligaments, meninges, myofascial expansions, periostea, retinaculae, septa, tendons, visceral fasciae, and all the intramuscular and intermuscular connective tissues including endo‐/peri‐/epimysium. These muscle layers may seem distinct in 2D sections, but the borders are somewhat arbitrary when viewed as an extensive 3 D network, with connective tissue fibers extending both along and across muscle fibers. The fascial system interpenetrates and surrounds all organs, muscles, bones and nerve fibers, endowing the body with a functional structure, and providing an environment that enables all body systems to operate in an integrated manner. Fascia is traditionally named according to the discrete anatomic structure that it surrounds which obscures its continuity and distinct layers.Fascial tissue provides a structural framework, continuously adapting and transmitting mechanical and chemical signals to differentiate tissue. The continuum of fascia throughout the body allows it to serve as a body‐wide mechanosensitive signaling system. The extracellular matrix plays an essential role in the development of skeletal musculature in the embryo. Fascia is a composite material of collagen fibers and matrix. In outer layers of the extremities and neck, fibers are found in parallel directions oriented at 55 degrees to the layer underneath, similar to a garden hose, which resists pressure and remains flexible. In other layers, collagen fibers are less regular and may have a wavy or helical structure. Fascia may also vary in proportions of collagen type I, III, IV and V and in rate of turnover. Fascial structure has functional implications. For example, when one muscle contracts against a thick, resistant fascia layer, the compartment pressure increases, and this pumps blood and lymphatic fluid against gravity and raises the contractile efficiency of other muscles in the same compartment. A fiber connects a muscle to the nitric oxide receptor of its arteriole, which is pulled open during contraction to increase blood flow. Thoracolumbar fascia balances abdominal and spinal muscle tension.Fascia is gaining interest from researchers, physicians and many types of therapists. Manual therapy techniques treat the fascial layers by altering density, tonus, viscosity, and the arrangement of fascia. Manual stimulation of sensory nerve endings may lead to tonus changes in muscle. The fascial system is now being recognized in the etiology of pain and proprioception. Fascia research can help understand aspects of musculoskeletal problems such as myofascial trigger points, low back pain, and fibromyalgia. Connective tissue influences the normal or pathological processes in a wide variety of organ systems e.g. intramuscular connective tissue architecture changes after immobilization of an extremity.The mechanical interactions among muscle, tendon and fascia in humans developed over many thousands of years and allow us to adapt to a wide range of activities. We are just beginning to understand these enough to develop specific fascial exercises and activities.This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Evidence of adaptations of locomotor neural drive in response to enhanced intermuscular connectivity between the triceps surae muscles of the rat.

The aims of this study were to investigate changes 1) in the coordination of activation of the triceps surae muscle group, and 2) in muscle belly length of soleus (SO) and lateral gastrocnemius (LG) during locomotion (trotting) in response to increased stiffness of intermuscular connective tissues in the rat. We measured muscle activation and muscle belly lengths, as well as hindlimb kinematics, before and after an artificial enhancement of the connectivity between SO and LG muscles obtained by implanting a tissue-integrating surgical mesh at the muscles' interface. We found that SO muscle activation decreased to 62%, while activation of LG and medial gastrocnemius muscles increased to 134 and 125%, respectively, compared with the levels measured preintervention. Although secondary additional or amplified activation bursts were observed with enhanced connectivity, the primary pattern of activation over the stride and the burst duration were not affected by the intervention. Similar muscle length changes after manipulation were observed, suggesting that length feedback from spindle receptors within SO and LG was not affected by the connectivity enhancement. We conclude that peripheral mechanical constraints given by morphological (re)organization of connective tissues linking synergists are taken into account by the central nervous system. The observed shift in activity toward the gastrocnemius muscles after the intervention suggests that these larger muscles are preferentially recruited when the soleus has a similar mechanical disadvantage in that it produces an unwanted flexion moment around the knee.NEW & NOTEWORTHY Connective tissue linkages between muscle-tendon units may act as an additional mechanical constraint on the musculoskeletal system, thereby reducing the spectrum of solutions for performing a motor task. We found that intermuscular coordination changes following intermuscular connectivity enhancement. Besides showing that the extent of such connectivity is taken into account by the central nervous system, our results suggest that recruitment of triceps surae muscles is governed by the moments produced at the ankle-knee joints.

A lumped stiffness model of intermuscular and extramuscular myofascial pathways of force transmission.

Mechanical behavior of skeletal muscles is commonly modeled under the assumption of mechanical independence between individual muscles within a muscle group. Epimuscular myofascial force transmission via the connective tissue network surrounding a muscle challenges this assumption as it alters the force distributed to the tendons of individual muscles. This study aimed to derive a lumped estimate of stiffness of the intermuscular and extramuscular connective tissues and to assess changes in such stiffness in response to a manipulation of the interface between adjacent muscles. Based on in situ measurements of force transmission in the rat plantar flexors, before and after resection of their connective tissue network, a nonlinear estimate of epimuscular myofascial stiffness was quantified and included in a multi-muscle model with lumped parameters which allows for force transmission depending on the relative position between the muscles in the group. Such stiffness estimate was assessed for a group with normal intermuscular connective tissues and for a group with increased connectivity, mimicking scar tissue development. The model was able to successfully predict the amount of epimuscular force transmission for different experimental conditions than those used to obtain the model parameters. The proposed nonlinear stiffness estimates of epimuscular pathways could be integrated in larger musculoskeletal models, to provide more accurate predictions of force when effects of mechanical interaction or altered epimuscular connections, e.g. after surgery or injury, are substantial.

Immunohistochemical Analysis of MMP-2 Expression in the Myocardium During the Postinfarction Period.

Immunohistochemical analysis revealed 2.5-fold increased of expression MMP-2 in myocardium samples during the early period (up to 3 days) of postinfarction reparative regeneration. During this period, MMP-2 was detected mainly in monocytes/macrophages circulating in the blood and migrating to the necrotic zone, while expression in the intermuscular and perivascular connective tissue was lower. At later terms, with development of large focal and diffuse cardiosclerosis, MMP-2 expression significantly decreased (to the initial level) and was detected mainly in the foci of intermuscular and perivascular fibrosis, its area in the sections increased by 1.8 times. Evaluation of MMP-2 expression in the blood vessels showed that the immunohistochemical reaction was the most pronounced in the walls of new sinusoidal vessels and the minimum in the intramural arteries of medium diameter. These results attest to an important role of MMP in connective tissue remodeling (proteolytic degradation) during the early period of postinfarction reparative regeneration. The decrease in MMP-2 expression observed at later terms correlated with myocardial fibrosis progression.

Anisotropic Tissue Motion Induced by Acupuncture Needling Along Intermuscular Connective Tissue Planes

Acupuncture needle manipulation causes mechanical deformation of connective tissue, which in turn results in mechanical stimulation of fibroblasts, with active changes in cell shape and autocrine purinergic signaling. We have previously shown using ultrasound elastography in humans that acupuncture needle manipulation causes measurable movement of tissue up to several centimeters away from the needle. The goal of this study was to quantify the spatial pattern of tissue displacement and deformation (shear strain) in response to acupuncture needling along an intermuscular connective tissue plane compared with needling over the belly of a muscle. Eleven (11) healthy human subjects underwent a single testing session during which robotic acupuncture needling was performed while recording tissue displacement using ultrasound. Outcome measures were axial and lateral tissue displacement as well as lateral shear strain calculated using ultrasound elastography postprocessing. Tissue displacement and strain extended further in the longitudinal direction when needling between muscles, and in the transverse direction when needling over the belly of a muscle. The anisotropic tissue motion observed in this study may influence the spatial distribution of local connective tissue cellular responses following acupuncture needle manipulation.

Tissue preference of some myxobolids (Myxozoa: Myxosporea) from the musculature of European freshwater fishes

For several species of fish myxosporeans known at present, the musculature has been designated as the location of intrapiscine development. In the majority of these cases, plasmodia and spores are actually found in the muscle cells, but there are also myxosporeans that select intermuscular connective tissue, fish bones, nerves and capillaries of the musculature as their site of development. During the plasmodial development of Myxobolus, Henneguya and Thelohanellus species in fish inhabiting Hungarian freshwaters, 3 main locations of development inside the muscles were identified. Pseudodispar-type plasmodia, such as M. cyprini, M. musculi and M. pseudodispar, form plasmodia intracellularly in the muscle cells, while the plasmodia of M. pfeifferi, M. sandrae and T. hovorkai develop in the intermuscular connective tissue. A similar development in the connective tissue of the ventricle and the bulbus arteriosus was observed for M. dogieli, a heart parasite found in some cyprinid fishes. The third type of development is represented by M. tauricus, which prefers the collagenous elements of the fin rays, but its plasmodia are commonly found in the muscle attached to the fish bones.

Immunolocalization of a beta-defensin (Tu-BD-1) in the skin and subdermal granulocytes of turtles indicate the presence of an antimicrobial skin barrier

The resistance of turtle skin to infections is likely due to the production of a thick corneous layer but also of soluble antimicrobial molecules released in the stratum corneum. The present study has determined the localization of beta-defensin peptides previously identified by biomolecular analysis in turtle skin. After the production of a specific antibody for one peptide indicated as Ts-BD-1, light and ultrastructural localization indicates that the peptide is mainly present in some variably dense primary granules of granulocytes. These cells are sparse in the connective tissues and within blood vessels present in the dermis and subdermal inter-muscular connective tissue. A weak labeling is also present in the epidermis, especially localized in sparse secretory granules discharged among corneocytes of the stratum corneum. This localization suggests that antimicrobial peptides are common constituents of the narrow extracellular spaces located among superficial corneocytes where bacteria or their remnants are frequently detected. The study suggests that turtle beta-defensins are mainly contained in granulocytes involved in the immunological surveillance of the skin and that they become active after skin wounding.

The relationship between structural/MHC changes in upper airway palatopharyngeal muscle morphology and obstructive sleep apnea/hypopnea syndrome

The aim of this study is to explore the relationship between structural/MHC changes in upper airway palatopharyngeal muscle morphology and obstructive sleep apnea/hypopnea syndrome. Palatopharyngeal muscle specimens were taken from 51 patients with obstructive sleep apnea hypopnea syndrome (OSAHS) who underwent uvulopalatopharyngoplasty (UPPP) resection. Patients were divided into light, medium and severe in terms of the severity of their OSAHS. There were 17 patients in each severity group. Palatopharyngeal muscle specimens were also taken from 17 patients suffering from chronic tonsillitis for comparison as the control group. All specimens were stained using Masson and observed for structural changes, especially in muscle fiber morphology, density and arrangement, as well as intermuscular connective tissues, under light microscopy. All specimens were also analyzed for MHC-I, MHC-IIa and MHC-IIb phenotype and protein expression differences using mRNA quantitative reverse transcription polymerase chain reaction (RT-PCR) and immunofluorescence staining. The results from each group were then statistically analyzed using semi-quantitative analysis. Light microscopy with Masson staining revealed that in the control group, the muscle fibers are closely connected and arranged neatly. In specimens from patients suffering from OSAHS, the palatopharyngeal muscle fibers are larger with obvious hypertrophy and there was an increase in elastic fibers. The mucosal lamina propria was thickened, and the density of muscle fibers was reduced. Muscle fibers are not neatly arranged and degeneration was observed. The amount of muscular pathology and fibrosis corresponds to the severity of disease in the patients. In patients with severe OSAHS, the proportion of collagen to muscle fibers was increased significantly. Immunofluorescence results reveal that there were significantly more fast muscle fibers and less slow muscle fibers in the study group than the control group. mRNA quantitative reverse transcription polymerase chain reaction (RT-PCR) revealed similar results, i.e., the proportion of MHC-II palatopharyngeal muscle fibers is higher in the study group than the control group, and increases with the severity of OSAHS. Pathological change occurs in both the collagen and muscle of OSAHS patients and corresponds to the degree of severity of OSAHS. Pathological change in palatopharyngeal muscle tissues is therefore, likely to be related to the occurrence and development of OSAHS. The increase in the proportion of the MHC-1I type fibers in OSAHS patients is likely to have an effect on the amount of airway support conferred by the muscle. This is likely the reason behind the lack of clinical improvement in some patients with severe OSAHS despite surgical treatment.

Three cases of Parafilaria bovicola infection in Belgium, and a few recent epidemiological observations on this emergent disease

Parafilariosis is a vectorborne parasitic disease caused by the development of the nematode Parafilaria bovicola in the subcutaneous and intermuscular connective tissues of cattle. On February 28, 2012, the so-called...

Three cases of Parafilaria bovicola infection in Belgium, and a few recent epidemiological observations on this emergent disease

Parafilariosis is a vectorborne parasitic disease caused by the development of the nematode Parafilaria bovicola in the subcutaneous and intermuscular connective tissues of cattle. On February 28, 2012, the so-called...

Different changes in mastication between crisp grass carp (Ctenopharyngodon idellus C.et V) and grass carp (Ctenopharyngodon idellus) after heating: The relationship between texture and ultrastructure in muscle tissue

In order to study special mastication of Crisp grass carp (CGC), the relationships between the texture and ultrastructure in raw fresh and heated CGC and grass carp (GC) were studied. In raw samples, all textural results of raw CGC (RCGC) were higher than those of raw GC (RGC). From the ultrastructural results, short muscle fiber diameter, dense fiber density, large collagen amounts, narrow intermyofibrillar spaces and gaps determined the texture of fillets. In the heated samples, the hardness, chewiness, resilience and springiness of heated CGC (HCGC) were higher than in heated CG (HCG). Compared to raw samples, the hardness, fracturability, springiness and chewiness of HCGC were higher than those of RCGC. However, all textural results of HGC were significantly reduced. The ultra-structural results showed that the better mastication of HCGC was connected with denaturation and coagulation of myofibrillar and sarcoplasmic proteins, the low ratio of shrinking in inter-muscular connective tissue, large interstitial material, much less fiber–fiber detachments and myofiber–myocommata detachments.

Refined distribution of myelinated trigeminal proprioceptive nerve fibres in Mueller's muscle as the mechanoreceptors to induce involuntary reflexive contraction of the levator and frontalis muscles

Stretching of mechanoreceptors in Mueller's muscle induces reflexive contraction of not only the levator muscle but also the frontalis muscle as two different eyelid-opening muscles. Previously, we reported that fine neural myelinated structures, acting as mechanoreceptors, were found in the proximal Mueller's muscle. Since there is a risk of misunderstanding that the middle and distal Mueller's muscle does not contain mechanoreceptors and can be invalidated or resected, the accurate distribution of myelinated trigeminal proprioceptive nerve fibres as mechanoreceptors in Mueller's muscle was refined horizontally in this study. We explored 10 whole Mueller's muscles between the levator muscle and the tarsus of the upper eyelids obtained from five Japanese cadavers. The specimens were serially sliced along the horizontal plane and stained with HE, S-100 protein to determine the presence of Schwann cells, and smooth muscle actin antibody to determine the presence of Mueller's smooth muscle fibres. Although all myelinated nerve fibres in the intermuscular connective tissues among the sympathetically innervated Mueller's multi-unit smooth muscle fibres may not correspond to the proprioceptive nerve fibres, the nerve bundles consisting of multiple myelinated nerve fibres were well distributed in the proximal Mueller's muscle, and single myelinated nerve fibres were well distributed in the middle and distal Mueller's muscle. We believe that the mechanoreceptors in Mueller's muscle consist of myelinated proprioceptive nerve fibres with nerve endings possibly attached to collagen fibres in the intermuscular connective tissues present among Mueller's smooth muscle fibres. As the myelinated nerve fibres innervate the middle and distal Mueller's muscle to a greater extent than those in the proximal Mueller's muscle, the former may be more important as mechanoreceptors than the latter and should not be invalidated or excised during surgery for treatment of blepharoptosis to prevent reduction of reflexive contraction of the levator and frontalis muscles.

Angiopoietin‐like protein 1 expression is related to intermuscular connective tissue and cartilage development

Angptl1, a member of the angiopoietin-related protein family, is known to regulate angiogenesis, but little is known of its potential role in other processes. To identify the expression pattern and possible role of angptl1 during embryogenesis, we used gene targeting to generate angptl1-deficient, nLacZ knockin mice. Staining for beta-galactosidase from embryonic day 9.5 to 6 months of age revealed that angptl1 was initially expressed in the paraxial mesoderm. Expression then shifted to intermuscular connective tissue (fascial plane), joint capsules, and perichondrium (laryngo-trachea, ribs, and long bones), but not the muscles. The vasculature, central and peripheral nervous systems, digestive, respiratory, and other major organ systems did not show any angptl1 expression. This expression pattern suggests that angptl1 is related to development of the connective tissue and cartilage. Lack of phenotype in mutant mice may be due to a functional redundancy from other related factors.