External Muscle Layers Research Articles

Lgr5 marks stem/progenitor cells contributing to epithelial and muscle development in the mouse esophagus

The existence and function of Lgr5+ cells within the developing esophagus remains unknown. Here, we document multiple discrete Lgr5+ populations in the developing mouse esophagus, predominantly within nascent epithelial and external muscle layers. Lgr5 expression initially emerges in the developing proximal embryonic epithelium, but progressively extends distally and persists within the distal epithelium of neonates. Fate mapping and ablation analyses reveal a long-term contribution of epithelial Lgr5+ cells to esophageal organogenesis. Additionally, Lgr5-expressing cells are present in the developing external muscle layer, particularly during the development of the striated component. Fate mapping reveals a significant contribution of these embryonic Lgr5+ cells to the adult muscle layer. Embryonic Lgr5+ epithelial cells are also found to be important for regulating epithelial development, serving as a key source of Wnt6, among other ligands, to promote epithelial cell proliferation and formation of epithelial layers. These findings significantly enhance our understanding of esophageal development and shed light on the involvement of Lgr5+ stem/progenitor cells during organogenesis. Importantly, this study lays the foundation for investigating esophageal diseases related to the Lgr5+ stem/progenitor cell pool.

Morphological analysis of the digestive tract of Antillean manatee (Trichechus manatus manatus, Linnaeus, 1758) in northeast Brazil

Morphological studies of the digestive tract are relevant to know the biology and understand the eating habits to conserve species. Our objective was to analyze macroscopically and microscopically the digestive tract of Antillean manatee (Trichechus manatus manatus). Samples were collected from 20 animals found dead stranded on the coast of northeastern Brazil or that died during the rehabilitation process in captivity between July 1995 and March 2017. The macroscopic analysis of the gastrointestinal tract was carried out from the in loco monitoring of the two necropsies. For microscopic evaluation, tissue fragments were collected during necropsy, fixed with 10% buffered formaldehyde and subjected to routine histological processing, with 5 μm thick slices, and subsequently submitted to the Hematoxylin-Eosin staining method, the Verhoeff method, and the periodic acid-Schiff method. Macroscopically, neonates and adults have the same digestive tract structures, namely esophagus, stomach, duodenum, jejunum, ileum, cecum, colon, and rectum. The microscopic analysis demonstrated that the digestive tract is formed by four histological layers (mucosa, submucosa, muscularis, and serosa or adventitia). In the esophagus, esophageal glands are absent and there are elastic fibers in the submucosal layer and between the external muscle and adventitial layers. The stomach has a structure called the cardiac gland, which microscopically presents ontogenetic differences regarding the depth of the lining epithelium and the orderly distribution of cells along the gastric gland. In the duodenal ampulla and in the diverticula, duodenal glands were identified in the submucosa. The luminal portion of the mucous layer of the cecal ampulla, colon, and rectum is lined by keratinized stratified squamous epithelium. The digestive tract of the species Antillean manatee is similar to what has been reported for the order Sirenia.

Prophylactic Sclerotherapy for Lymphatic Complications After Living Donor Renal Transplant: A Single-Center Experience.

Lymphocele formation after kidney transplant is a common complication that causes significant morbidity. In this study, we aimed to evaluate the safety and effectiveness of intraoperative prophylactic povidone-iodine sclerotherapy through the closed suction drain to prevent lymphocele after kidney transplant. In this retrospective comparative single-institution study, we compared patients who underwent intraoperative prophylactic povidone-iodine sclerotherapy through the closed suction drain (group A) with patients who did not receive sclerotherapy (group B). Patients were treated between September 2017 and July 2023. Atthe end of the kidney transplant surgery, after the closure of the external oblique muscle layer and before skin closure, 10 mL of 10% povidone-iodine in 40 mL of normal saline were instilled via the closed suction drain and dwelled in the cavity for 30 minutes. During the study period, 300 living-related donor kidney transplants were performed. Prophylactic povidone-iodine sclerotherapy was performed in 150 patients (50%).We noted a significantly lower incidence of lymphorrhea and lymphocele in group A. On postoperative days 1 and 5, we noted a significant reduction in drain output in group A (P < .001). One patient in group A and 5 patients in group B required ultrasonography-guideddrainage andpovidone-iodine sclerotherapy. No sclerotherapy-related complications were reported after a median follow-up of 16 months (range, 3-29 months). Intraoperative prophylactic povidoneiodine sclerotherapy appears to be an easy, safe, and effective procedure for preventing lymphatic complications after living donor kidney transplant.

A study on the congruence and proximity of the sling and clasp fibres at the cardio-esophageal junction of the stomach.

The cardio-oesophageal sphincter that is located in close longitudinal proximity to the origin of the lesser curvature of the stomach has a unique pattern of external muscle fibres whose inner oblique layer would normally form an elongated sling and the middle partially circular layer would form a projecting clasp into the already existing muscular sling of the former congruently, which would result in the formation of an anatomical sphincter in that area that would normally be devoid of the external longitudinal muscle layer coat. Certain authors have disagreed with the notion of this standard literature and have proposed that the clasp and sling fibres need not necessarily be congruent and may even remain independent of each other with partial contributions from the longitudinal muscle layers as well that may arise tangentially in different populations, which may in turn contribute to reflux oesophagitis in that population. Hence, the clasp and sling fibre muscular patterns were observed in six formalin-embalmed cadavers at the department of anatomy in a tertiary care institute as part of routine dissections in series, and the findings were then reported. At the junction of the lesser curvature of the stomach with the oesophagus, all six cadavers showed a longitudinal sling pattern as opposed to the conventional oblique sling. The circular muscle layer was found to be merged with the outer longitudinal muscle layer to form the sling that pulled away from the clasp, resulting in a loss of congruency for the same. The clasp fibres, however, were found to be contributed by the inner oblique muscle layer. The conventional perpendicular or tangential merging of the clasp with the sling was not observed; instead, an obtuse, blunt angular merging of the clasp with the sling was observed. The deviation of the sling from the clasp could indicate a lack of a proper fit between them at the cardio-oesophageal sphincter. The lack of robustness in the attachment of the clasp to the sling may possibly contribute to the diminished taut pull of the clasp in this subset of the population. These would be significant determinants for a predisposition to reflux oesophagitis and Barrett's oesophagus.

Histological Effects of Aqueous Extract of Saffron Flowers Crocus sativus on Ovaries and Oviduct of Females White Mice Mus musculus

The present study was conducted to identify the histological effects of the aqueous extract of saffron flower on ovaries and oviducts of the adult female mouse at doses of 15, 30 and 60 mg/kg of body weight (b.w.).for the periods 7,15 and 30 days, respectively and once a day. Behavioral changes were include the abnormal hyperactivity, irritability followed by introversion and reduction of motor activity, as well as loss of appetite for food and drinking water for several hours. The results showed histopathological changes of mice ovaries at a dose of 15 mg /kg of B.W. for the above periods a slight increase in primordial follicles, congestion of blood vessels, necrosis and degeneration. At a dose of 30 mg/kg. there was slight deposition of hyaline material, deposition of hemosiderin dye, congestion and increase of primordial follicles numbers, while at a dose of 60 mg/kg lymphatic cells infiltration were observed, with some ovarian stromal cells decaying. while the oviduct, and for the above periods changes included thickening of canal wall, endothelial cells degeneration and blood vessel congestion in the muscular area at a dose of 15 mg/kg, increased flattening of the mucosal folds also was observed. At a dose of 30mg /kg. an increased damage with increased blood vessels congestion, fibrosis of oviduct wall and degeneration of the external muscle layer of the oviduct at a dose of 60 mg /kg was obvious.

Role of Macrophages and Mast Cells as Key Players in the Maintenance of Gastrointestinal Smooth Muscle Homeostasis and Disease.

The gut contains the largest macrophage pool in the body, with populations of macrophages residing in the mucosa and muscularis propria of the gastrointestinal (GI) tract. Muscularis macrophages (MMs), which are located within the muscularis propria, interact with cells essential for GI function, such as interstitial cells of Cajal, enteric neurons, smooth muscle cells, enteric glia, and fibroblast-like cells, suggesting that these immune cells contribute to several aspects of GI function. This review focuses on the latest insights on the factors contributing to MM heterogeneity and the functional interaction of MMs with other cell types essential for GI function. This review integrates the latest findings on macrophages in other organs with increasing knowledge of MMs to better understand their role in a healthy and diseased gut. We describe the factors that contribute to (muscularis macrophage) MM heterogeneity, and the nature of MM interactions with cells regulating GI function. Finally, we also describe the increasing evidence suggesting a critical role of another immune cell type, the mast cell, in normal and diseased GI physiology.

Neuronal regulation of the gut immune system and neuromodulation for treating inflammatory bowel disease.

The gut immune system in the healthy intestine is anti‐inflammatory, but can move to a pro‐inflammatory state when the gut is challenged by pathogens or in disease. The nervous system influences the level of inflammation through enteric neurons and extrinsic neural connections, particularly vagal and sympathetic innervation of the gastrointestinal tract, each of which exerts anti‐inflammatory effects. Within the enteric nervous system (ENS), three neuron types that influence gut immune cells have been identified, intrinsic primary afferent neurons (IPANs), vasoactive intestinal peptide (VIP) neurons that project to the mucosa, and cholinergic neurons that influence macrophages in the external muscle layers. The enteric neuropeptides, calcitonin gene‐related peptide (CGRP), tachykinins, and neuromedin U (NMU), which are contained in IPANs, and VIP produced by the mucosa innervating neurons, all influence immune cells, notably innate lymphoid cells (ILCs). ILC2 are stimulated by VIP to release IL‐22, which promotes microbial defense and tissue repair. Enteric neurons are innervated by the vagus, and, in the large intestine, by the pelvic nerves. Vagal nerve stimulation reduces gut inflammation, which may be both by stimulation of efferent (motor) pathways to the ENS, and stimulation of afferent pathways that connect to integrating centers in the CNS. Efferent pathways from the CNS have their anti‐inflammatory effects through either or both vagal efferent neurons and sympathetic pathways. The final neurons in sympathetic pathways reduce gut inflammation by the action of noradrenaline on β2 adrenergic receptors expressed by immune cells. Activation of neural anti‐inflammatory pathways is an attractive option to treat inflammatory bowel disease that is refractory to other treatments. Further investigation of the ways in which enteric reflexes, vagal pathways and sympathetic pathways integrate their effects to modulate the gut immune system and gut inflammation is needed to optimize neuromodulation therapy.

Microanatomical and secretory characterization of the salivary gland of the Rhodnius prolixus (Hemiptera, Reduviidae, Triatominae), a main vector of Chagas disease.

Rhodnius prolixus is the principal vector of Trypanosoma cruzi, the aetiological agent of Chagas disease in American countries. This insect is haematophagous during all life cycles and, to antagonize its haemostatic, inflammatory and immune systems, it secretes saliva while feeding on the vertebrate host's blood. Here, we investigated characteristic changes of the salivary glands (SG) that occur during insect development. Two pairs of lobules and ducts comprise the SG of R. prolixus. The organ's size increases over time, but the microanatomical structures are preserved during insect development. Both lobules have a single layer epithelium formed by binucleated cells, which surrounds the saliva reservoir. The principal lobule presents higher polysaccharide and total protein contents than the accessory lobe. A network of external muscle layers is responsible for organ contraction and saliva release. Apocrine, merocrine and holocrine secretion types occur in the secretory epithelium. Dopamine, serotonin and tyrosine-hydroxylase are neural-related molecules that regulate SG function both during and after feeding.

FMRF-related peptides in Aedes aegypti midgut: neuromuscular connections and enteric nervous system.

FMRFamide-related peptides (FaRPs) are a class of neuropeptides that participate in a variety of physiological processes in invertebrates. They occur in nerves of stomatogastric ganglia and enteroendocrine cells of the insect digestive tract, where they may control muscle functions. However, their direct involvement in muscle function has never been shown in situ. We studied the relationship between FaRPs and midgut muscle during larval-pupal transition of the mosquito Aedes aegypti. In late L4, FaRP-positive neuronal extensions attach to the bundles of the external circular muscle layer, and muscle stem cells start to undergo mitosis in the internal circular layer. Thereafter, the external muscle layer degenerates, disappearing during early pupal development, and is completely absent in the adult mosquito. Our results indicate that FaRP-based neural signals are involved in the reorganization of the muscle fibers of the mosquito midgut during the larval-pupal transition. In addition to confirming FaRP involvement in muscle function, we show that the mosquito midgut muscles are largely innervated, and that circular and longitudinal muscle have specific neuron bodies associated with them.

Effects of Coffee and Its Components on the Gastrointestinal Tract and the Brain-Gut Axis.

Coffee is one of the most popular beverages consumed worldwide. Roasted coffee is a complex mixture of thousands of bioactive compounds, and some of them have numerous potential health-promoting properties that have been extensively studied in the cardiovascular and central nervous systems, with relatively much less attention given to other body systems, such as the gastrointestinal tract and its particular connection with the brain, known as the brain–gut axis. This narrative review provides an overview of the effect of coffee brew; its by-products; and its components on the gastrointestinal mucosa (mainly involved in permeability, secretion, and proliferation), the neural and non-neural components of the gut wall responsible for its motor function, and the brain–gut axis. Despite in vitro, in vivo, and epidemiological studies having shown that coffee may exert multiple effects on the digestive tract, including antioxidant, anti-inflammatory, and antiproliferative effects on the mucosa, and pro-motility effects on the external muscle layers, much is still surprisingly unknown. Further studies are needed to understand the mechanisms of action of certain health-promoting properties of coffee on the gastrointestinal tract and to transfer this knowledge to the industry to develop functional foods to improve the gastrointestinal and brain–gut axis health.

Claudin-18 Loss Alters Transcellular Chloride Flux but not Tight Junction Ion Selectivity in Gastric Epithelial Cells.

Background & AimsTight junctions form a barrier to the paracellular passage of luminal antigens. Although most tight junction proteins reside within the apical tight junction complex, claudin-18 localizes mainly to the basolateral membrane where its contribution to paracellular ion transport is undefined. Claudin-18 loss in mice results in gastric neoplasia development and tumorigenesis that may or may not be due to tight junction dysfunction. The aim here was to investigate paracellular permeability defects in stomach mucosa from claudin-18 knockout (Cldn18-KO) mice.MethodsStomach tissue from wild-type, heterozygous, or Cldn18-KO mice were stripped of the external muscle layer and mounted in Ussing chambers. Transepithelial resistance, dextran 4 kDa flux, and potential difference (PD) were calculated from the chambered tissues after identifying differences in tissue histopathology that were used to normalize these measurements. Marker expression for claudins and ion transporters were investigated by transcriptomic and immunostaining analysis.ResultsNo paracellular permeability defects were evident in stomach mucosa from Cldn18-KO mice. RNAseq identified changes in 4 claudins from Cldn18–KO mice, particularly the up-regulation of claudin-2. Although claudin-2 localized to tight junctions in cells at the base of gastric glands, its presence did not contribute overall to mucosal permeability. Stomach tissue from Cldn18–KO mice also had no PD versus a lumen-negative PD in tissues from wild-type mice. This difference resulted from changes in transcellular Cl– permeability with the down-regulation of Cl– loading and Cl– secreting anion transporters.ConclusionsOur findings suggest that Cldn18-KO has no effect on tight junction permeability in the stomach from adult mice but rather affects anion permeability. The phenotype in these mice may thus be secondary to transcellular anion transporter expression/function in the absence of claudin-18.

Peculiarities of Histological Structure of Pulmonary Veins in Patients with Total Anomalous Pulmonary Venous Drainage as Morphological Substrates Relating to Formation of Postoperative Pulmonary Venous Obstruction.

The histological and immunohistochemical methods were employed to examine the peculiarities of histological structure of pulmonary veins and left atrium of the heart in norm and in various types of total anomalous drainage of pulmonary veins. In contrast to normal pulmonary vein covered with external multiple muscle layers (myocardial sleeve), such sleeve is absent in veins that have no connection with the left atrium irrespective of the type of the defect. In patients with total anomalous pulmonary venous drainage, the structure of left atrium was heterogeneous featuring either the presence or absence of inner angiomural lining in this atrium. The structural peculiarities are important for insight into etiology of the development of postoperative pulmonary venous obstruction in patients with total anomalous pulmonary venous drainage.

Anatomical and functional relationships between external abdominal oblique muscle and posterior layer of thoracolumbar fascia

The abdominal muscles are important for the stability of the lumbar region through the thoracolumbar fascia (TLF). However, there is not full agreement regarding the posterior transversal continuity of the external abdominal oblique muscle (EO) with the TLF. To clarify this point, 10 cadavers and computed tomography (CT) images from 27 subjects were used to evaluate the transversal continuity of the TLF with the abdominal muscles. The width of the fascial continuity of the EO with the posterior layer of TLF along the posterior border of the EO was also measured (40.70 ±3.92 mm). The epimysial fascia of the EO was in direct continuity with the posterior layer of TLF in eight cadavers and 23 CT images, whereas in two cadavers and four CT images, the epimysial fascia of the EO first fused with the fascia covering the latissimus dorsi, and then, both fasciae were in continuity with the posterior layer of TLF. Therefore, the transversal fascial continuity of the EO could explain the transmission of tension from the EO to the posterior layer of TLF and its importance in maintaining the stability of the lumbar spine through a hydraulic effect. Regarding fascial continuity in the trunk, and taking the EO into consideration, the TLF is formed by the fascia of all the abdominal muscles as the rectus sheath. In this manner, myofascial continuity between the TLF and the abdominal muscles is achieved through the aponeurosis and fascia, which ensures synchronization between the erector spinae and the rectus abdominis. Clin. Anat. 31:1092-1098, 2018. © 2018 Wiley Periodicals, Inc.

Anatomical and functional relationships between external abdominal oblique muscle and posterior layer of thoracolumbar fascia.

The abdominal muscles are important for the stability of the lumbar region through the thoracolumbar fascia (TLF). However, there is not full agreement regarding the posterior transversal continuity of the external abdominal oblique muscle (EO) with the TLF. To clarify this point, 10 cadavers and computed tomography (CT) images from 27 subjects were used to evaluate the transversal continuity of the TLF with the abdominal muscles. The width of the fascial continuity of the EO with the posterior layer of TLF along the posterior border of the EO was also measured (40.70 ±3.92 mm). The epimysial fascia of the EO was in direct continuity with the posterior layer of TLF in eight cadavers and 23 CT images, whereas in two cadavers and four CT images, the epimysial fascia of the EO first fused with the fascia covering the latissimus dorsi, and then, both fasciae were in continuity with the posterior layer of TLF. Therefore, the transversal fascial continuity of the EO could explain the transmission of tension from the EO to the posterior layer of TLF and its importance in maintaining the stability of the lumbar spine through a hydraulic effect. Regarding fascial continuity in the trunk, and taking the EO into consideration, the TLF is formed by the fascia of all the abdominal muscles as the rectus sheath. In this manner, myofascial continuity between the TLF and the abdominal muscles is achieved through the aponeurosis and fascia, which ensures synchronization between the erector spinae and the rectus abdominis. Clin. Anat. 31:1092-1098, 2018. © 2018 Wiley Periodicals, Inc.

KARAKTERISTIK MORFOLOGI ESOFAGUS DAN LAMBUNG BANDIKUT (Echymipera kalubu) (Esophagus and Stomach Morphological Characteristic of Bandicoot Echymipera kalubu (Marsupialia: Peroryctidae))

The morphological characteristics of the stomach and esophagus of five adults bandicoot (Echymipera kalubu) with average 1.16±0.29 kg in body weight and 38.2±4.76 cm in body length were studied macroscopically, microscopically and histochemically. The bandicoot esophagus were found relatively long about one third of body length. The esophageal glands were identified along the esophagus and the number decreased gradually from cranial to caudal region. In addition of smooth muscle, skeletal muscles were also examined in the external muscle layer of esophagus up to the esophageal junction. The stomach of the E. Kalubu had short lesser curvature and three glandular regions of cardiac, fundic and pyloric glands were observed, respectively. The cardiac glands area was small and concentrated in the cranial part of the stomach. The fundic glands area occupied about half parts of the stomach. Mucous surface epithelial cells, mucous neck cells, parietal cells and chief cells were found in the entire fundic gland. The parietal cells were the most abundant cells in the major curvature distributed from the basal to neck area of the glands, but few in the minor curvature. Chief cells were mostly distributed in the basal gland. The pyloric glands region was observed in caudal part of the stomach. Staining with alcian blue-periodic acid Schift (AB-PAS) showed various distribution and intensity of neutral and acid mucopolysaccharides in the esophageal and stomach mucosa. High concentration of neutral and acid mucopolysaccharides were detected in esophageal and stomach glands with various concentration. Morphological characteristics of the esophagus and stomach were assumed to be related to the digestive processes in the gastrointestinal tract of bandicoot.

Morphological Study of the Oesophagus and Stomach of the Cave Swiflets (Collocalia linchi)

This study was conducted with aim to tend out morphology of oesophagus and stomach of the cave swiflets (Collocalia linchi) at macroscopic and microscopic levels. The data revealed that esophagus was 2.93 cm in length and possessed no crop. The stomach was small and the isthmus was not clear. Mucosa of the esophagus was lined by stratified squoamus epithelium. Esophageal gland was mucous type. The glands were well developed and distributed along the esophagus. The external muscle layer consisted of inner circular and outer longitudinal layers. The stomach could be distinguished into proventriculus and ventriculus with no clear isthmus between them. The mucosa of proventriculus was lined by single columnar epithelium. The ventricular gland area was divided into cardiac, fundic and pyloric gland areas. The surface of ventriculus was lined with cuticula. In general the esophagus and stomach of the cave swiftlets were simple with no crop in the esophagus and isthmus in the stomach. These might be related with the kind of food and feeding behavior of this species.

Intrinsic Gastrointestinal Macrophages: Their Phenotype and Role in Gastrointestinal Motility.

There is an increasing awareness of the role of macrophages in the regulation and maintenance of gastrointestinal function in health and disease. This work has proceeded in the context of an increased understanding of the complex phenotypic variation in macrophages throughout the body and has shown previously unidentified roles for macrophages in diseases such as gastroparesis, postoperative ileus, and inflammatory bowel disease. Opportunities for exploiting the phenotypic modulation of tissue resident macrophages have been identified as possible therapies for some of these diseases. In addition, macrophages are an established component of the innate immune system and can respond to variations and changes in the intestinal microbiome and potentially mediate part of the impact of the microbiota on intestinal health. We reviewed the latest work on novel concepts in defining macrophage phenotype, discuss possible mechanisms of action for tissue-resident macrophages in the gut, address the significance of microbiome effects on macrophage phenotype, and review the known and possible roles of macrophages in motility disorders of the gastrointestinal tract.

Circumferential cryoablation in a strictured esophagus: a feasibility and dose-finding study in a porcine model after inducing stenosis by endoscopic mucosal resection.

In the treatment of early esophageal Barrett's neoplasia, radiofrequency ablation may be hindered by stenosis due to prior endoscopic resection (ER). The flexible balloon-based circumferential CryoBalloon Ablation System (CBAS) may overcome this problem by the conformability of the compliant balloon which might enable circumferential cryoablation in a stenosis. The aim of the current study was to evaluate the feasibility of the CBAS as well as the dose-response effect of cryoablation in a strictured esophagus model. In six pigs, a stenosis was induced by ER (3 cm in length, 75% of circumference) in the proximal, mid, and distal esophagus. After 28 days, cryoablation with the CBAS was performed, with the length of ablation time (6, 8, or 10 seconds) randomly assigned per stricture location within the esophagus. Four days post-ablation, the esophagi were harvested for histopathological assessment of the percentage of the total circumference affected by cryoablation and the maximum depth of necrosis. At 28 days, all 18 ER areas had transformed into strictures with ±50% of its original diameter remaining. In 9 of 18 strictures, more than one attempt for cryoablation was necessary due to displacement of the balloon. Histopathological evaluation showed a wide range in circumferential uniformity (0-100%) and maximum necrosis depth (epithelium to external proper muscle layer) of cryoablation, both independent of ablation times. Deepest ablation effects were seen at the center of the resection-induced scar. This first generation CryoBalloon Focal Ablation System was not feasible for ablation within severe stenoses, since it results in inconsistent circumferential uniformity of cryoablation with subsequent differences in depth of ablation. Further research with a next generation CBAS in a more realistic stricture model is warranted.

Disruption of the salivary gland muscle in tsetse, Glossina pallidipes Austen, as a result of salivary gland hypertrophy virus infection.

The secretory region of the salivary glands in Glossina pallidipes Austen (Diptera: Glossinidae) is characterized by an external muscle layer. Scanning electron microscopy and transmission electron microscopy investigations provide a detailed description of the longitudinal muscle fibres and a comparison of their structure when affected by salivary gland hypertrophy virus. The virus is responsible for hypertrophy of the salivary glands in symptomatic flies, specifically of the muscle fibres, the cytoarchitecture of which is completely altered. Although observations did not reveal viral particles in the muscle cells of either asymptomatic or symptomatic flies, muscle fibres were enlarged and detached from one another and their associated basement membrane only in symptomatic flies. A decrease in type IV collagen labelling in the basement membrane of the muscles in symptomatic flies is reported and is considered a potential cause of the salivary gland muscle alteration and, possibly, myopathy. The maintenance of an organized muscular layer is essential for the normal secretion of saliva and hence its pathology in symptomatic tsetse flies could affect the normal transmission of the trypanosome that develops inside the salivary gland epithelium. Therefore, a better understanding of the possible role of the virus is essential in order to elucidate its impact on salivary deployment in symptomatic flies.

Lack of striated muscle fibers in the longitudinal anal muscle of elderly Japanese: a histological study using cadaveric specimens

The aim of this study is to investigate variations in the longitudinal anal muscle (LAM), especially in the meeting pattern between the levator ani and rectum at the origin of the LAM. We examined the histology of the anal canal and the lower rectum of 50 cadavers (25 males, 25 females) of elderly Japanese individuals with the aid of immunohistochemistry. We observed two patterns in the meeting site between the levator ani and the rectum. In type 1, observed in 26 specimens, the smooth muscle-rich fascia lining the internal or medial aspect of the levator ani (i.e., the fascia pelvis parietalis or endopelvic fascia) was connected to the external muscle layer. In type 2, observed in 24 specimens, multiple intramuscular septa of the levator ani were attached to a smooth muscle mass, with the latter joining the external smooth muscle layer of the rectum. However, 21 specimens (6 type 1 and 15 type 2) carried few smooth muscles at the meeting site. We did not find any striated muscle in the LAM, although this might have been the result of age-associated degeneration. Thus, active traction of the pelvic viscera by the LAM seemed unlikely in elderly Japanese. Rather than playing an active role, as suggested by the integral pelvic floor theory, the LAM seemed to be an elastic skeleton that maintains the shape of the anal canal.