Skeletal Muscle Bundles Research Articles

Resistance Training with Co-ingestion of Anti-inflammatory Drugs Attenuates Mitochondrial Function.

Aim: The current study aimed to examine the effects of resistance exercise with concomitant consumption of high vs. low daily doses of non-steroidal anti-inflammatory drugs (NSAIDs) on mitochondrial oxidative phosphorylation in skeletal muscle. As a secondary aim, we compared the effects of eccentric overload with conventional training.Methods: Twenty participants were randomized to either a group taking high doses (3 × 400 mg/day) of ibuprofen (IBU; 27 ± 5 year; n = 11) or a group ingesting a low dose (1 × 75 mg/day) of acetylsalicylic acid (ASA; 26 ± 4 year; n = 9) during 8 weeks of supervised knee extensor resistance training. Each of the subject's legs were randomized to complete the training program using either a flywheel (FW) device emphasizing eccentric overload, or a traditional weight stack machine (WS). Maximal mitochondrial oxidative phosphorylation (CI+IIP) from permeabilized skeletal muscle bundles was assessed using high-resolution respirometry. Citrate synthase (CS) activity was assessed using spectrophotometric techniques and mitochondrial protein content using western blotting.Results: After training, CI+IIP decreased (P < 0.05) in both IBU (23%) and ASA (29%) with no difference across medical treatments. Although CI+IIP decreased in both legs, the decrease was greater (interaction p = 0.015) in WS (33%, p = 0.001) compared with FW (19%, p = 0.078). CS activity increased (p = 0.027) with resistance training, with no interactions with medical treatment or training modality. Protein expression of ULK1 increased with training in both groups (p < 0.001). The increase in quadriceps muscle volume was not correlated with changes in CI+IIP (R = 0.16).Conclusion: These results suggest that 8 weeks of resistance training with co-ingestion of anti-inflammatory drugs reduces mitochondrial function but increases mitochondrial content. The observed changes were not affected by higher doses of NSAIDs consumption, suggesting that the resistance training intervention was the prime mediator of the decreased mitochondrial phosphorylation. Finally, we noted that flywheel resistance training, emphasizing eccentric overload, rescued some of the reduction in mitochondrial function seen with conventional resistance training.

Riedel’s thyroiditis in a 78 year old male: a rare experience.

We present a rare case of Riedel’s thyroiditis in a 78-year-old male, native of hilly region of Nepal who presented with chief complaint of long standing swelling of the thyroid with discharging sinus. Right hemithyroidectomy with excision of sinus was done. Gross examination showed asymmetrically enlarged right lobe of thyroid with adherent fibroadipose and muscular tissue. Microscopy revealed diffuse hyalinised fibrosis of the thyroid parenchyma with presence of variable number of atrophic to few normal thyroid follicles in between. The stroma showed dense lymphoplasmacytic infiltration with foci of calcifications and hemorrhage. There was extension of fibrosis beyond the thyroid capsule, encasing the skeletal muscle bundles at many places. Diagnosis of Riedel’s thyroiditis was made.Riedel’s thyroiditis is a rare entity but can occasionally be encountered. Various imaging modalities may not be helpful for the definite diagnosis. Diagnostic thyroidectomy should be performed for the accurate diagnosis and further management. DOI: 10.21276/APALM.1392

MACRO AND MICROSCOPIC MORPHOLOGY OF LYSSA BODY IN DOG

With the aim to study the gross and histomorphology of the lyssa body of dog, seven heads were collected from the healthy adult dogs used for dissection purpose in the laboratory of the Department of Anatomy and Histologyat Bangladesh Agricultural University, Mymensingh. The gross parameters such as weight, length and width were recorded for respective specimens.The present study revealed that the dog lyssa was pinkish white coloured and situated along the median plane on the ventral surface of the free portion of the tongue. The lyssa had more or less rod shaped. The weight, length and width of the lyssa were measured as 0.11 ± 0.01gm, 3.96 ± 0.4cm and 0.28 ± 0.03cm, respectively.Then the specimens were processed for histomorphology and stained with Hematoxylin and Eosin. The present study noticed that the entire body of the lyssa was formed from adipose tissue and striated muscle bundles, encircled by a thick connective tissue capsule of mainly collagen fibers.These results will be helpful to study the further functional importance of the lyssa body in dog.

First report of cutaneous infiltrative lipoma in goldfish Carassius auratus

Goldfish Carassius auratus is the most popular ornamental species, widely present in private and public aquaria. In the present case, 2 goldfish exhibited bilateral, multiple, variably sized, round, pale-white, soft, protruding masses on the body. The microscopic examination of the masses revealed well-differentiated adipocytes infiltrating the subcutaneous skeletal muscle bundles. The histological lesions were consistent with infiltrative lipoma. To our knowledge, this is the first report of cutaneous infiltrative lipoma in goldfish.

ORAL SARCOID LESION ASSOCIATED WITH DISCOID LUPUS ERYTHEMATOSUS: A CASE REPORT

A 54-year-old female patient with previous diagnosis of untreated discoid lupus erythematosus presented a 3-month history of labial nodular growths. This patient reported a previous injury on the nose, with the diagnosis of granulomatous dermatitis. Physical examination revealed multiple, firm, sessile, and normochromic labial nodules with approximately 2.0 × 3.0 cm. An incisional biopsy was performed and histopathologic examination revealed a fibrous connective tissue containing non-caseating compact granulomas that invaded the skeletal muscle and preserved nerve bundles. Grocott and Wade Fite staining were negative and the histopathologic finding was suggestive of sarcoid granulomas. Other laboratory tests were performed and supported this diagnosis (serum levels of angiotensin converting enzyme, immunoglobulins, alkaline phosphatase, calcium, urinary calcium, Montenegro's reaction, thoracic computed tomography, creatinine, and complete blood count). Before initiation of treatment, the lesions spontaneously regressed, and a follow-up at 18 months showed no recurrence.

Resistance Exercise Attenuates Mitochondrial Function

Although nonsteroidal anti-inflammatory drugs (NSAIDs) have been shown to modulate skeletal muscle adaptations and protein metabolism in response to resistance exercise, little is known about the effects of NSAIDs on mitochondrial function. Thus, the current study aimed to examine the effects of resistance exercise with concomitant NSAID consumption on mitochondrial oxidative phosphorylation in skeletal muscle. Twenty participants were randomized in a single-blinded fashion to either an experimental group receiving ibuprofen (IBU: 27±5 yr; n=11; 1200 mg/d) or a control group receiving a low-dose acetylsalicylic acid (CON: 26±4 yr; n=9; 75 mg/d) During this period, subjects performed 8 weeks of supervised resistance exercise involving the knee extensors muscles. Each of the subject’s legs were randomized to complete the training program using either a flywheel (FW) device emphasizing eccentric-overload, or a traditional weight stack machine (WS). Maximal mitochondrial oxidative phosphorylation (OXPHOS) from permeabilized skeletal muscle bundles was assessed using high resolution respirometry before and after the training intervention. Citrate synthase activity was assessed using spectrophotometric techniques. After training, OXPHOS decreased (P<0.05) in both IBU (23%) and CON (29%) with no difference across medical treatments. Although OXPHOS decreased in both legs, the decrease was greater (interaction P=0.015) in WS (33%, P=0.015) than in FW (19%, P=0.078). Citrate synthase (CS) did not change after the intervention. The increase in quadriceps muscle volume was not significantly correlated with the change in OXPHOS (R=0.15). These results suggest that 1) eight weeks of resistance training reduces mitochondrial function but not mitochondrial content, 2) The decreased mitochondrial function with resistance exercise was not affected by ibuprofen consumption, 3) flywheel resistance training, emphasizing eccentric overload, rescues some of the reduction in mitochondrial function seen with conventional resistance training.

CUG-BP, Elav-like family member 1 (CELF1) is required for normal myofibrillogenesis, morphogenesis, and contractile function in the embryonic heart.

CUG-BP, Elav-like family member 1 (CELF1) is a multifunctional RNA binding protein found in a variety of adult and embryonic tissues. In the heart, CELF1 is found exclusively in the myocardium. However, the roles of CELF1 during cardiac development have not been completely elucidated. Myofibrillar organization is disrupted and proliferation is reduced following knockdown of CELF1 in cultured chicken primary embryonic cardiomyocytes. In vivo knockdown of Celf1 in developing Xenopus laevis embryos resulted in myofibrillar disorganization and a trend toward reduced proliferation in heart muscle, indicating conserved roles for CELF1 orthologs in embryonic cardiomyocytes. Loss of Celf1 also resulted in morphogenetic abnormalities in the developing heart and gut. Using optical coherence tomography, we showed that cardiac contraction was impaired following depletion of Celf1, while heart rhythm remained unperturbed. In contrast to cardiac muscle, loss of Celf1 did not disrupt myofibril organization in skeletal muscle cells, although it did lead to fragmentation of skeletal muscle bundles. CELF1 is required for normal myofibril organization, proliferation, morphogenesis, and contractile performance in the developing myocardium. Developmental Dynamics 245:854-873, 2016. © 2016 Wiley Periodicals, Inc.

Cell Density and Joint microRNA-133a and microRNA-696 Inhibition Enhance Differentiation and Contractile Function of Engineered Human Skeletal Muscle Tissues

To utilize three-dimensional (3D) engineered human skeletal muscle tissue for translational studies and in vitro studies of drug toxicity, there is a need to promote differentiation and functional behavior. In this study, we identified conditions to promote contraction of engineered human skeletal muscle bundles and examined the effects of transient inhibition of microRNAs (miRs) on myogenic differentiation and function of two-dimensional (2D) and 3D cultures of human myotubes. In 2D cultures, simultaneously inhibiting both miR-133a, which promotes myoblast proliferation, and miR-696, which represses oxidative metabolism, resulted in an increase in sarcomeric α-actinin protein and the metabolic coactivator PGC-1α protein compared to transfection with a scrambled miR sequence (negative control). Although PGC-1α was elevated following joint inhibition of miRs 133a and 696, there was no difference in myosin heavy chain (MHC) protein isoforms. 3D engineered human skeletal muscle myobundles seeded with 5 × 10(6) human skeletal myoblasts (HSkM)/mL and cultured for 2 weeks after onset of differentiation consistently did not contract when stimulated electrically, whereas those seeded with myoblasts at 10 × 10(6) HSkM/mL or higher did contract. When HSkM were transfected with both anti-miRs and seeded into fibrin hydrogels and cultured for 2 weeks under static conditions, twitch and tetanic specific forces after electrical stimulation were greater than for myobundles prepared with HSkM transfected with scrambled sequences. Immunofluorescence and Western blots of 3D myobundles indicate that anti-miR-133a or anti-miR-696 treatment led to modest increases in slow MHC, but no consistent increase in fast MHC. Similar to results in 2D, only myobundles prepared with myoblasts treated with anti-miR-133a and anti-miR-696 produced an increase in PGC-1α mRNA. PGC-1α targets were differentially affected by the treatment. HIF-2α mRNA showed an expression pattern similar to that of PGC-1α mRNA, but COXII mRNA levels were not affected by the anti-miRs. Overall, joint inhibition of miR-133a and miR-696 accelerated differentiation, elevated the metabolic coactivator PGC-1α, and increased the contractile force in 3D engineered human skeletal muscle bundles.

Organization of the dorsoventral musculature in the wings of the pteropod mollusc Clione limacina

AbstractThe wings of the pteropod mollusc Clione limacina provide forward propulsive force through flapping movements in which the wings bend throughout their length in both dorsal and ventral directions. The musculature of the wings includes oblique, striated muscle bundles that generate the swimming movements of the wings, longitudinal and transverse (smooth) muscle bundles that collapse the wings and pull them into the body during a wing withdrawal response, and dorsoventral muscles that control the thickness of the wings. All muscles act against a hydrostatic skeleton that forms a central hemocoelic space within the wings. Of these muscle types, all have been thoroughly described and studied except the dorsoventral muscles. The fortuitous discovery that the dorsoventral musculature can be intensely labeled with an antibody against the vertebrate hyperpolarization‐activated cation channel (HCN2) provided the opportunity to describe the organization of the dorsoventral musculature in detail. In addition, electrical recordings and microelectrode dye injections supported the immunohistochemical data, and provided preliminary data on the activity of the muscle fibers. The organization and activity of the dorsoventral musculature suggests it may be involved in regulation of wing stiffness during the change from slow to fast swimming.

Acellular bi-layer silk fibroin scaffolds support functional tissue regeneration in a rat model of onlay esophagoplasty

Surgical management of long-gap esophageal defects with autologous gastrointestinal tissues is frequently associated with adverse complications including organ dysmotility, dysphagia, and donor site morbidity. In order to develop alternative graft options, bi-layer silk fibroin (SF) scaffolds were investigated for their potential to support functional tissue regeneration in a rodent model of esophageal repair. Onlay esophagoplasty was performed with SF matrices (N = 40) in adult rats for up to 2 m of implantation. Parallel groups consisted of animals implanted with small intestinal submucosa (SIS) scaffolds (N = 22) or sham controls receiving esophagotomy alone (N = 20). Sham controls exhibited a 100% survival rate while rats implanted with SF and SIS scaffolds displayed respective survival rates of 93% and 91% prior to scheduled euthanasia. Animals in each experimental group were capable of solid food consumption following a 3 d post-op liquid diet and demonstrated similar degrees of weight gain throughout the study period. End-point μ-computed tomography at 2 m post-op revealed no evidence of contrast extravasation, fistulas, strictures, or diverticula in any of the implant groups. Ex vivo tissue bath studies demonstrated that reconstructed esophageal conduits supported by both SF and SIS scaffolds displayed contractile responses to carbachol, KCl and electrical field stimulation while isoproterenol produced tissue relaxation. Histological (Masson's trichrome and hematoxylin and eosin) and immunohistochemical (IHC) evaluations demonstrated both implant groups produced de novo formation of skeletal and smooth muscle bundles positive for contractile protein expression [fast myosin heavy chain (MY32) and α-smooth muscle actin (α-SMA)] within the graft site. However, SF matrices promoted a significant 4-fold increase in MY32+ skeletal muscle and a 2-fold gain in α-SMA+ smooth muscle in comparison to the SIS cohort as determined by histomorphometric analyses. A stratified squamous, keratinized epithelium expressing cytokeratin 5 and involucrin proteins was also present at 2 m post-op in all experimental groups. De novo innervation and vascularization were evident in all regenerated tissues indicated by the presence of synaptophysin (SYP38)+ boutons and vessels lined with CD31 expressing endothelial cells. In respect to SIS, the SF group supported a significant 4-fold increase in the density of SYP38+ boutons within the implant region. Evaluation of host tissue responses revealed that SIS matrices elicited chronic inflammatory reactions and severe fibrosis throughout the neotissues, in contrast to SF scaffolds. The results of this study demonstrate that bi-layer SF scaffolds represent promising biomaterials for onlay esophagoplasty, capable of producing superior regenerative outcomes in comparison to conventional SIS scaffolds.

Tongue of Laughing Dove (Stigmatopelia senegalensis): Histochemical and Ultrastructural Characteristics

This study examined the morphology and histology of the adult laughing dove tongue from birds of both sexes and compared the results those reported in the literature concerning other bird species. The tongue of the adult laughing dove has an elongated triangular shape and a median groove. Both dorsal and ventral lingual surfaces were covered by keratinized stratified squamous epithelium, which decreased in thickness and degree of keratinization, when progressing toward the root. The dorsal surface of the lingual apex and body showed desquamated epithelial cells with differences in size, shape and appearance of these cells according to their location on the tongue. The openings of lingual glands were observed on the ventrolateral surface of the caudal half of the body of the tongue. A narrow rim of fibrous connective tissue beneath the epithelium surrounding the central lingual core was composed of a single cartilaginous plate and skeletal muscle bundles. Large conical papillae were located symmetrically between the body and root of the tongue. An additional row of conical papillae were located behind the previously mentioned row. The ventral aspect of the tongue was free from any papillae but had numerous shallow folds in addition to a row of three openings for lingual salivary glands.

Age-related different relationships between ectopic adipose tissues and measures of central obesity in sedentary subjects.

Accumulation of fat at ectopic sites has been gaining attention as pivotal contributor of insulin resistance, metabolic syndrome and related cardiovascular complications. Intermuscular adipose tissue (IMAT), located between skeletal muscle bundles and beneath muscle fascia, has been linked to physical inactivity, ageing and body mass index, but little is known about its relationship with the other AT compartments, in particular with increasing age. To address this issue, erector spinae IMAT, epicardial (EAT), intraabdominal (IAAT) and abdominal subcutaneous adipose tissue (SAT) were simultaneously measured by Magnetic Resonance Imaging (MRI) and related to waist circumference measurements and age in 32 sedentary subjects without cardiovascular disease (18 men; 14 women; mean age 48.5±14 years). Fasting glucose, triglycerides and HDL-cholesterol were also assessed. We observed that, after dividing individuals according to age (≤ or >50 years), IMAT and EAT depots were significantly more expanded in older subjects (63.2±8.3 years) than in the younger ones (38.4±5.2 years) (p<0.001). Overall, both IMAT and EAT showed stronger positive associations with increasing age (β = 0.63 and 0.67, respectively, p<0.001 for both) than with waist circumference (β = 0.55 and 0.49, respectively, p<0.01 for both) after adjusting for gender. In addition, the gender-adjusted associations of IMAT and EAT with waist circumference and IAAT were significant in individuals ≤50 years only (p<0.05 for all) and not in the older ones. In contrast, no age-related differences were seen in the relationships of IAAT and SAT with waist circumference. Finally, serum triglycerides levels turned out not to be independently related with ectopic IMAT and EAT. In conclusion, the expansion of IMAT and EAT in sedentary subjects is more strongly related to age than waist circumference, and a positive association of these ectopic depots with waist circumference and IAAT amount can be postulated in younger individuals only.

Congenital midline cervical cleft.

Congenital midline cervical cleft.

Hamartomatous Polyp of Minor Salivary Gland Arising in the Tongue: A Report of the First Case

Benign tumorous condition can be encountered at very unusual location in oral cavity and pharyngeal region, which leads diagnostic difficulty. Here we describe a very unusual presentation of polypoid hamartoma on the root of the tongue. A 59-year-old woman presented with a polypoid tumor mass on the dorsal root of the tongue. Microscopically, it was hamartoma showing normal salivary glands of mucinous and serous types, lymphoid hyperplasia, and skeletal muscle bundles. Major differential diagnoses include accessory tongue, adenomatoid hyperplasia, and idiopathic hyperplasia of sublingual glands. To our knowledge, this is the first report of hamartoma arising in the root of the tongue presenting as polypoid mass. Correct diagnosis based on pathologic examination is essential for proper treatment.

A light microscopic study on tongue development in Korean native goats (Capra hircus)

The purpose of this study was to identify the composition and organization of lingual tissues underlying the histo-structural change of developing tongue in Korean native goats by light microscopy (LM). Tongues of the fetuses on days 60, 90, 120 and neonate were examined for the morphological development. In the 60-day-old fetuses, the tongue tissues were differentiated into epithelium, lamina propria and muscle layer. Primordia of filiform, conical, lentiform, fungiform and vallate papillae appeared and rudiments of taste bud were observed in the epithelia of the primordia of the gustatory papillae. The dorsal surface of the lingual epithelia showed a weak PAS positive reaction. Collagenous fibers and small blood vessels were shown in the connective tissues. In the 90-day-old fetuses, Von Ebner’s glands were moderately PAS positive while the muscle fibers and connective tissue were strongly positive for PAS. The collagenous fibers increased and came to have a more complex arrangement in the tongue. The muscle fibers were spread out at various directions and developed in striated muscle bundles. In the 120-day-old fetuses, taste buds were observed in the epithelia of the gustatory papillae, and several well-developed tissues visible such as blood vessels, collagenous fibers, muscle fiber bundles and Von Ebner’s glands. In the neonates, many taste buds were found in a transverse section of the vallate papilla. The muscle layers, Von Ebner’s glands, collagenous fibers and blood vessels were more developed than those of the 120-day old fetuses. These findings indicate that goat tongues have a variety of different shapes during prenatal development.

Recombinant insulin-like growth factor-1 activates satellite cells in the mouse urethral rhabdosphincter

BackgroundThe goal of this study is to demonstrate the efficacy of a new method for the treatment of urinary incontinence by stimulation of urethral rhabdosphincter satellite cells. We show that satellite cells do exist in the sphincter muscle of retired male mice breeders by staining for c-Met, a satellite cell specific protein. Once activated by recombinant mouse Insulin-like Growth Factor-1(rIgf-1), the satellite cells develop into muscle cells within the rhabdosphincter thereby potentially strengthening it.Methods20 μl (1 μg/μl) of rIgf-1 was surgically injected directly into the urethral wall of retired male mouse breeders. Mice injected with phosphate buffered saline (PBS) were used as controls. 4 weeks later, urethras were harvested and serially-sectioned through the sphincter for routine hematoxylin-eosin staining as well as immunohistochemical staining with satellite cell specific anti-c-Met antibody and proliferation specific anti-Ki-67 antibody.ResultsAnti-c-Met antibody positive cells (c-Met+) were identified in the rhabdosphincter. c-Met+ cells increased by 161.8% relative to controls four weeks after rIGF-1 injection. Anti- Ki-67 antibody positive cells were identified and characterized as cells with centrally located nuclei in striated muscle bundles of rIGF-1 treated animals.ConclusionsSatellite cells in the mouse rhabdosphincter can be activated by rIGF-1 treatment, which subsequently are incorporated into existing skeletal muscle bundles. Using this approach, the rhabdosphincter can be induced to regenerate and potentially strengthen via satellite cell activation and likely improve urinary continence.

Mature Intracranial Teratoma

SUMMARY Teratomas constitute a group of nongerminomatous germ cell tumors that are composed of an admixture of different tissue types representative of ectoderm, endoderm and mesoderm. Intracranial teratomas are rare, comprising approximately 0.5% of all intracranial tumors. They preferentially involve the midline structures, and occur primarily in children. We presented an unusual case of mature intracranial teratoma with extracranial extension in a 24-year-old man who complained of headache, nausea and vomiting. The intracranial expansive lesion was localized in the left frontotemporobasal region extending into the ipsilateral orbit. The patient underwent total resection of the tumor. No adjuvant treatment was given. On gross examination, the resected tumor was lobulated, containing heterogeneous solid and cystic components. Histologic investigation revealed the presence of various fully differentiated tissues representative of the three germ cell layers, including adipose tissue, cartilage, bone, striated muscle bundles, brain tissue, respiratory epithelium and glandular structures. The diagnosis of mature teratoma was established. Follow-up at four years did not show any evidence of recurrence. The presented case is an unusual example of mature teratoma with regards to the age of the patient and, especially, to the location of the tumor, both intraand extracranially. It is critical to recognize this rare entity by extensive sampling to rule out the presence of immature elements which may constitute only a minor part of the tumor.

Vagal afferent innervation of the lower esophageal sphincter

To supply a fuller morphological characterization of the vagal afferents innervating the lower esophageal sphincter (LES), specifically to label vagal terminals in the tissues forming the LES in the gastroesophageal junction, the present experiment employed injections of dextran biotin into the nodose ganglia of rats. Four types of vagal afferents innervated the LES. Clasp and sling muscle fibers were directly and prominently innervated by intramuscular arrays (IMAs). Individual IMA terminals subtended about 16° of arc of the esophageal circumference, and, collectively, the terminal fields were distributed within the muscle ring to establish a 360° annulus of mechanoreceptors in the sphincter wall. 3D morphometry of the terminals established that, compared to sling muscle IMAs, clasp muscle IMAs had more extensive arbors and larger receptive fields. In addition, at the cardia, local myenteric ganglia between smooth muscle sheets and striated muscle bundles were innervated by intraganglionic laminar endings (IGLEs), in a pattern similar to the innervation of the myenteric plexus throughout the stomach and esophagus. Finally, as previously described, the principle bundle of sling muscle fibers that links LES sphincter tissue to the antropyloric region of the lesser curvature was innervated by exceptionally long IMAs as well as by unique web ending specializations at the distal attachment of the bundle. Overall, the specialized varieties of densely distributed vagal afferents innervating the LES underscore the conclusion that these sensory projections are critically involved in generating LES reflexes and may be promising targets for managing esophageal dysfunctions.

Rhabdomyomatous (Mesenchymal) Hamartoma Presenting as Haemangioma on the Upper Lip: A Case Report with Immunohistochemical Analysis and Treatment with High-Power Lasers

Rhabdomyomatous hamartoma is a rare disease that occurs predominantly in the skin. This paper describes a congenital lesion in a 17-year-old male, who came to our clinic presenting a circumscribed swelling involving the oral mucosa and vermillion border of the upper lip, purplish in color, and blanching under pressure. The patient reported that he had had lesion since his birth. A clinical diagnosis was of congenital haemangioma, and the patient was treated by photocoagulation using diode laser. When the lesion became smaller, by having its blood content reduced, the upper portion of the lesion was sliced off with CO2 laser and the tissue was sent for microscopic analysis. Histopathological examination showed an oral mucosa fragment with proliferation of striated muscle bundles admixed with small blood vessels, collagen, and nerve fibres. A supplementary analysis with immunohistochemistry demonstrated positivity for desmin, HHF35, smooth muscle actin, S-100, and CD34. Based on these findings, the lesion was diagnosed as rhabdomyomatous hamartoma. The aesthetic result has been very satisfactory after a 14-month followup.

Study of human adult parotid duct in the area of penetration through buccinator muscle and their functional relationship as a sphincter.

The adult human parotid duct is roughly 6-8 cm long. From the parotid gland, parotid duct traverses through masseter muscle, penetrates through buccinator muscle, and opens into the oral cavity. This unique form of the parotid duct is likely correlated with the function of the duct, directly affected by the movement of the buccinator muscle during mastication and swallowing. Histological structure of the duct is known to be different in each region, and details of smooth muscle present in the parotid duct are mostly unclear. In this study, we conducted SEM and histological observations of the area where the parotid duct penetrates the buccinator muscle, and an observation of smooth muscle to investigate its existence using alpha-smooth muscle antibody. We confirmed the presence of an abundance of skeletal muscle bundles likely originating from the buccinator muscle under the epithelium of the parotid duct wall in the region where it penetrates the buccinator muscle. We also observed that some of the muscle fibers were completely attached to the epithelium. We observed a lack of smooth muscle in this region of the duct wall. From these results, we suggest that the area of the duct penetrating buccinator muscle plays a role in regulating the salivary passage through the contraction of the surrounding buccinator muscle fibers.