Longitudinal Smooth Muscle Layer Research Articles

Understanding Samaana Vaata in relation to the physiology of digestion

Ayurveda is a way of life governed by the principle that whatever there is in the universe is there in the body also. The concept of Tridosha is one such theory which decides the well-being and the diseased condition of a human being. That is, when in equilibrium leads to health and when vitiated, leads to disease. Vaata being one of the Tridosha leads the other two Dosha, Mala, Dhatus as the wind carries the clouds in the sky. There are five types of Vaata, i.e., Prana, Udana, Samana, Vyana and Apana. Samaana, is situated near Jatharagni and moves all over the Koshta. The function of Samaana Vaata can be corelated with functions such as Grahana, Pachana, Vivechana, Munchana. The myenteric plexus, or plexus of Auerbach, is located between the longitudinal and circular smooth muscle layers of the muscularis in gastrointestinal tract. The motor neurons of these plexus mostly control GI tract motility (movement), particularly the frequency and strength of contraction of the muscularis. This can be co-related to Karma of Samana Vata like Grahana, Munchana. The submucosal plexus, also known as Meissner’s plexus, is a network of autonomic motor nerve fibres located in the submucosa of the gastrointestinal tract. The motor neurons of the submucosal plexus supply the secretory cells of the mucosal epithelium, controlling the secretions and absorption of the organs of the gastrointestinal tract. This can be co-related to Karma of Samana Vaata like Pachana, Vivechana. Hence this article is aimed at further exploration of these anatomical and physiological aspects.

The Multidirectional Effect of Nitrite Oxide the Longitudinal and Circular Smooth Muscle Layers of the Wall of the Stomach and Duodenum

The Multidirectional Effect of Nitrite Oxide the Longitudinal and Circular Smooth Muscle Layers of the Wall of the Stomach and Duodenum

Gastric neurons in the nucleus tractus solitarius are selective to the orientation of gastric electrical stimulation

Objective. Gastric electrical stimulation (GES) is a bioelectric intervention for gastroparesis, obesity, and other functional gastrointestinal disorders. In a potential mechanism of action, GES activates the nerve endings of vagal afferent neurons and induces the vago-vagal reflex through the nucleus tractus solitarius (NTS) in the brainstem. However, it is unclear where and how to stimulate in order to optimize the vagal afferent responses. Approach. To address this question with electrophysiology in rats, we applied mild electrical currents to two serosal targets on the distal forestomach with dense distributions of vagal intramuscular arrays (IMAs) that innervated the circular and longitudinal smooth muscle layers. During stimulation, we recorded single and multi-unit responses from gastric neurons in NTS and evaluated how the recorded responses depended on the stimulus orientation and amplitude. Main results. We found that NTS responses were highly selective to the stimulus orientation for a range of stimulus amplitudes. The strongest responses were observed when the applied current flowed in the same direction as the IMAs in parallel with the underlying smooth muscle fibers. Our results suggest that gastric neurons in NTS may encode the orientation-specific activity of gastric smooth muscles relayed by vagal afferent neurons. Significance. This finding suggests that the orientation of GES is critical to effective engagement of vagal afferents and should be considered in light of the structural phenotypes of vagal terminals in the stomach.

Histomorphometric analysis of mature female Japanese quail (Coturnix coturnix japonica) stomach

The study analyzed the histomorphometry of the mature female Japanese quail (Coturnix coturnix japonica) stomach with the aid of ImageJ software. The different histological parts were identified using a compound microscope. Five mature laying female Japanese quail were collected and necropsied. The digestive organs, particularly proventriculus and gizzard, were collected and processed for tissue staining. Histological identification and measurement of thickness and depth of various structures were subsequently performed. Comparable to other avian species, the proventriculus was comprised of four layers: thin tunica serosa (22.69 µm), tunica muscularis (235.07 µm) with outer longitudinal and inner circular smooth muscle layers, thick tunica submucosa (2,164.37 µm) containing glands, and innermost tunica mucosa (553.42 µm) with papillae. The gizzard was characterized by four tunics: thin tunica serosa (60.44 µm), thick tunica muscularis (1,480.07 µm), tunica submucosa (112.25 µm), and tunica mucosa (456.15 µm) where the glands, crypts, and koilin can be found. The findings suggest that the histology of proventriculus and gizzard of the Japanese quail have no remarkable difference compared to other poultry species. However, the histomorphometry of the organs examined had remarkable variations as compared to other avians.

Gut lumen formation defect can cause intestinal atresia: evidence from histological studies of human embryos and intestinal atresia septum

Intestinal atresia (IA), a common cause of neonatal intestinal obstruction, is a developmental defect, which disrupts the luminal continuity of the intestine. Here, we investigated (i) the process of lumen formation in human embryos; and (ii) how a defective lumen formation led to IA. We performed histological and histochemical study on 6-10 gestation week human embryos and on IA septal regions. To investigate the topology of embryonic intestine development, we conducted 3D reconstruction. We showed that a 6-7th gestation week embryonic gut has no lumen, but filled with mesenchyme cells and vacuoles of a monolayer of epithelial cells. A narrow gut lumen was formed by gestation week-9, the gut was filled with numerous vacuoles of different sizes, some vacuoles were merging with the developing embryonic gut wall. At gestation week-10, a prominent lumen was developed, only few vacuoles were present and were merging with the intestine wall. At IA septal regions, vacuoles were located in the submucous layer, covered by a single layer of epithelium without glandular structure, and surrounded with fibrous tissue. The mucosal epithelium was developed with lamina propria and basement membrane, but the submucosa and the longitudinal smooth muscle layers were not properly developed. Hence, the vacuoles in IA septum could represent a remnant of vacuoles of embryonic gut. In conclusion, the fusion of vacuoles with the developing intestine wall associates with the disappearance of vacuoles and gut lumen formation in human embryos, and perturbation of these developmental events could lead to IA.

Distribution and morphology of P2X3-immunoreactive subserosal afferent nerve endings in the rat gastric antrum.

The present study investigated the morphological characteristics of subserosal afferent nerve endings with immunoreactivity for the P2X3 purinoceptor (P2X3) in the rat stomach by immunohistochemistry of whole-mount preparations using confocal scanning laser microscopy. P2X3 immunoreactivity was observed in subserosal nerve endings proximal and lateral to the gastric sling muscles in the distal antrum of the lesser curvature. Parent axons ramified into several lamellar processes to form net-like complex structures that extended two-dimensionally in every direction on the surface of the longitudinal smooth muscle layer. The axon terminals in the periphery of P2X3-immunoreactive net-like structures were flat and looped or leaf-like in shape. Some net-like lamellar structures and their axon terminals with P2X3 immunoreactivity were also immunoreactive for P2X2. P2X3-immunoreactive nerve fibers forming net-like terminal structures were closely surrounded by S100B-immunoreactive terminal Schwann cells, whereas axon terminals twined around these cells and extended club-, knob-, or thread-like protrusions in the surrounding tissues. Furthermore, a retrograde tracing method using fast blue dye indicated that most of these nerve endings originated from the nodose ganglia of the vagus nerve. These results suggest that P2X3-immunoreactive subserosal nerve endings have morphological characteristics of mechanoreceptors and contribute to sensation of a mechanical deformation of the distal antral wall associated with antral peristalsis.

Human adipose-derived mesenchymal stem cells accelerate decellularized neobladder regeneration.

Decellularized natural bladder matrices (neobladders) represent an exciting means to regenerate the bladder following bladder cancer-associated cystectomy. In this study, we compare the evolution of decellularized matrices with recellularized matrices by seeding it with human adipose-derived mesenchymal stem cells (ADSC) after implantation following partial cystectomy in rats. We discovered significant anatomical differences since 10 days after neobladder implantation with the ADSC-containing matrices promoting a significant recovery of mature p63- and cytokeratin 7-positive urothelium. We also discovered significantly induced expression of the vimentin mesoderm marker in the submucosal layer in ADSC-seeded matrices. Interestingly, we found a higher expression of smooth muscle actin in transversal and longitudinal smooth muscle layers with ADSC-seeded matrices. Furthermore, ADSC also showed increased vascularization and nerve innervation of the neobladder as determined by the distribution of CD31 and S100β reactivity, respectively. We believe that ADSC and their paracrine-acting pro-regenerative secretome within decellularized matrices represent an efficient bladder substitution strategy; however, we require a fuller understanding of the mechanisms involved before clinical studies can begin.

A structured review on the female urethral anatomy and innervation with an emphasis on the role of the urethral longitudinal smooth muscle.

A damaged sphincteric unit or support system, unstable urethral deformability or damaged sensory innervation are all potential causes of a dysfunctional urethral sphincter. With the current improvement in pharmacological targets and urodynamic understanding, studies have begun quantifying individual structures and their importance in closure pressure and consequently urethral continence. However, when it comes to the function of the longitudinal urethral smooth muscle layer, there is currently no consensus. The intent of this structured review is to critically examine literature regarding the female urethral anatomy and closure mechanism. We hypothesized that the longitudinal smooth muscle is a prerequisite for sufficient urethral closure and not merely involved during micturition. Overall opinions on a dysfunctional closure mechanism are controversial. Nonetheless, basic mechanics may be applied to understand simple urodynamics. With the assumption of longitudinal muscles forming a plug when contracted, this could have a substantial effect on the continence mechanism.

Morphology of the Uterotubal Junction of the Cheetah (Acinonyx jubatus).

Less than 7,000 cheetahs survive in the wild. Captive breeding has proved notoriously difficult. The uterotubal junction acts as major barrier and regulator to the passage of sperm. This study describes the morphology of the uterotubal junction of the cheetah. Reproductive tracts were obtained from seven cheetahs that succumbed from natural causes or were euthanized for humane reasons. The uterotubal junction was isolated and examined macroscopically and microscopically. The extramural isthmus made a characteristic 90° bend before entering the mesometrial border of the uterus close to its tip. The intramural isthmus had approximately four primary folds lined by nonciliated cuboidal to low cuboidal epithelium. The Tunica muscularis was robust, merged with its uterine counterparts and consisted of an inner circular layer and outer longitudinal smooth muscle layer. The uterine ostium opened via a muscular and glandular papilla that projected from the apex of the uterine lumen. A sharply demarcated circular zone of simple columnar epithelial cells surrounded the uterine ostium and separated the simple cuboidal to low cuboidal cells of the isthmus and uterine epithelium from each other. Branched tubulo-alveolar glands, some with dilated lumens, were present in the papilla and sometimes extended into the adjacent endometrium. These glands might act as sperm storage areas, and could easily be confused with cystic endometrial hyperplasia. Low transverse endometrial ridges surrounded the papilla and extended caudally for a short distance before disappearing. The uterine glands were lined by a simple cuboidal epithelium. Anat Rec, 302:1855-1864, 2019. © 2019 American Association for Anatomy.

Effects of Redox Disturbances on Intestinal Contractile Reactivity in Rats Fed with a Hypercaloric Diet.

Few studies have associated the effects of changes in caloric intake and redox disturbances in the gastrointestinal tract. Therefore, the present study aimed at evaluating the hypercaloric diet consumption influence on the contractile reactivity of intestinal smooth muscle, morphology, and oxidative stress of rat ileum. Wistar rats were randomly divided into groups that received a standard diet and fed with a hypercaloric diet for 8 weeks. Animals were euthanized, and the ileum was isolated to isotonic contraction monitoring. Morphology was evaluated by histological staining and oxidative stress by quantification of malondialdehyde levels and total antioxidant activity. Cumulative concentration-response curves to KCl and carbachol were attenuated in rats fed with a hypercaloric diet compared to those that received a standard diet. In addition, an increase in caloric intake promotes a rise in the thickness of the longitudinal smooth muscle layer of rat ileum and tissue malondialdehyde levels, characterizing lipid peroxidation, as well as a decrease in the antioxidant activity. Thus, it was concluded that the consumption of a hypercaloric diet impairs rat intestinal contractility due to mechanisms involving modifications in the intestinal smooth muscle architecture triggered by redox disturbances.

Immunohistochemical Study on the Ruminal Wall of Adult Baladi Goats (Capra hircus)

A total number of eight Baladi goats (Capra hircus)of both sexes aged between 11-18 months-old were used to describe the histological structure of the ruminal wallin addition to investigate the immunohistochemical localization and distribution of ki-67, caspase 3 and vimentin. The results revealed no sex differences in the ruminal wall histology or immunohistochemistry.Histologically, the ruminal wall consisted of mucosa-submucosa, muscularis and serosa. The mucosaof the rumen was thrown into ruminal papillae that were coveredby keratinized epithelium. The submucosa was consisted of loose connective tissue lacking glands. Circular and longitudinal smooth muscle layers were the components ofmuscularis however, the rumen was surrounded externally by typical serosa. The immunohistochemical study was done using theavidin-biotin immunoperoxidase method. Ki-67 immunostaining was limited to nuclei of basal cells layer in the ruminal epitheliumwhich explained the importanceof ki-67 in epithelial cells proliferation as well askeratin biosynthesis. Caspase 3 immunostaining was localized in cytoplasm and nuclei of some epithelial cells that were going to apoptosis.The vimentinimmunostaining was widely spread in epithelial cells as well as,fibroblasts in propria and submucosa, and endothelia of blood vessels.This showed theimportance of vimentin asan intermediate filament protein. Detection of vimentin in the glial cells of enteric plexuses indicatedits supportive role in the nervous control of the rumen. Overall, the histological and immunohistochemical findings of this study explainedthe structure-function relationship of the rumen of Baladi goats

Identification of uterine pacemaker regions at the myometrial-placental interface in the rat.

Key Points Coordinated contraction of the uterine smooth muscle is essential to parturition.Histologically and physiologically defined pacemaker structures have not been identified in uterine smooth muscle.Here we report combined electrophysiological and histological evidence of zones associated with pacemaker activity in the rat myometrium.Our method relies crucially on the integration of histological and electrophysiological data in an in silico three‐dimensional reconstruction of the rat myometrium at 10 μm resolution.We find that myometrial/placental pacemaking zones are closely related with placental sites and the area of disruptive myometrial remodelling surrounding such sites.If analogues of the myometrial/placental pacemaking zone are present in the human, defining their histology and physiology will be important steps towards treatment of pre‐term birth, pre‐eclampsia, and postpartum haemorrhage. Coordinated uterine contractions are essential for delivering viable offspring in mammals. In contrast to other visceral smooth muscles, it is not known where excitation within the uterus is initiated, and no defined pacemaking region has hitherto been identified. Using multi‐electrode array recordings and high‐resolution computational reconstruction of the three‐dimensional micro‐structure of late pregnant rat uterus, we demonstrate that electrical potentials are initiated in distinct structures within the placental bed of individual implantation sites. These previously unidentified structures represent modified smooth muscle bundles that are derived from bridges between the longitudinal and circular layers. Coordinated implantation and encapsulation by invading trophoblast give rise to isolated placental/myometrial interface bundles that directly connect to the overlying longitudinal smooth muscle layer. Taken together, these observations imply that the anatomical structure of the uterus, combined with site‐specific implantation, gives rise to emergent patterns of electrical activity that drive effective contractility during parturition.

Exogenous transforming growth factor-β1 enhances smooth muscle differentiation in embryonic mouse jejunal explants.

An ex vivo experimental strategy that replicates in vivo intestinal development would in theory provide an accessible setting with which to study normal and dysmorphic gut biology. The current authors recently described a system in which mouse embryonic jejunal segments were explanted onto semipermeable platforms and fed with chemically defined serum‐free media. Over 3 days in organ culture, explants formed villi and they began to undergo spontaneous peristalsis. As defined in the current study, the wall of the explanted gut failed to form a robust longitudinal smooth muscle (SM) layer as it would do in vivo over the same time period. Given the role of transforming growth factor β1 (TGFβ1) in SM differentiation in other organs, it was hypothesized that exogenous TGFβ1 would enhance SM differentiation in these explants. In vivo, TGFβ receptors I and II were both detected in embryonic longitudinal jejunal SM cells and, in organ culture, exogenous TGFβ1 induced robust differentiation of longitudinal SM. Microarray profiling showed that TGFβ1 increased SM specific transcripts in a dose dependent manner. TGFβ1 proteins were detected in amniotic fluid at a time when the intestine was physiologically herniated. By analogy with the requirement for exogenous TGFβ1 for SM differentiation in organ culture, the TGFβ1 protein that was demonstrated to be present in the amniotic fluid may enhance intestinal development when it is physiologically herniated in early gestation. Future studies of embryonic intestinal cultures should include TGFβ1 in the defined media to produce a more faithful model of in vivo muscle differentiation. Copyright © 2017 The Authors Journal of Tissue Engineering and Regenerative Medicine Published by John Wiley & Sons, Ltd

Ileal Smooth Muscle Thickness is Greater in Young Obese Zucker Rats

Obesity is a risk factor for many pathologies including heart disease, type 2 diabetes and certain types of cancers. At this time little is known about how obesity effects the morphology of the small intestine or gut. The purpose of this study was to determine what morphological differences exist in the smooth muscle of the small intestine, between lean and obese Zucker rats. We hypothesized that the thickness of the circular and longitudinal muscle layers of the small intestine from obese Zucker rats would be greater compared to their lean counterparts. Ileum and jejunum from lean and obese Zucker rats were harvested, fixed in buffered formalin overnight, processed, and embedded in paraffin. Thin cross sections of the tissues were mounted on slides, stained with H&E followed by analyses of longitudinal and circular smooth muscle layer thicknesses using digital photos and FIJI/IMageJ software (version 1.5). Smooth muscle thickness data was exported from an Excel document and statistics performed utilizing GraphPad Prism (version 6.0). In addition, ileum from lean and obese Zucker rats was harvested, bisected lengthwise with the lacteals facing up, and fixed in 4% PFA overnight and then washed with sucrose solutions. The ileum tissues were pinned onto 6‐well silicone plates and strips of villi (1‐2 thick) were cut under a dissecting microscope. The villi strips were incubated with a LYVE‐1 antibody to identify lymphatic endothelial cells of the lacteals and a PECAM‐1 antibody to label microcirculation within the villi. Longitudinal and circular smooth muscle layers, identified in the ileum with H&E staining, were significantly thicker in 8‐week old obese Zucker rats compared to lean rats. No significant differences in smooth muscle thickness were observed in 12‐week or 26–32‐week old obese versus lean rats in either the ileum or the jejunum. Histological data obtained from the small intestine partially supports the hypothesis that intestinal smooth muscle layer thickness in obese juvenile Zucker rats was greater, but only at the 8‐week time point. Preliminary immunolabeling with LYVE‐1 positively identified the structure of the lacteal, while the PECAM‐1 labeling was strong within the microvasculature of the villi. Although additional studies with human tissue, e.g., samples derived from intestinal biopsies or surgical resection, are required to understand the biomedical significance of our findings, our data raise the possibility that for humans at a young age obesity may cause structural changes in the small intestine.Support or Funding InformationThis work was supported by an APS IOSP Undergraduate Summer Research Fellowship IOS‐1238831.

Multi-phenotypic Role of Serum Response Factor in the Gastrointestinal System.

Serum response factor (SRF) is a master transcription factor of the actin cytoskeleton that binds to highly conserved CArG boxes located within the majority of smooth muscle cell (SMC)-restricted promoters/enhancers. Although most studies of SRF focus on skeletal muscle, cardiac muscle, and vascular SMCs, SRF research has recently expanded into the gastrointestinal (GI) system. Genome scale analyses of GI SMC transcriptome and CArG boxes (CArGome) have identified new SRF target genes. In addition to circular and longitudinal smooth muscle layers, SRF is also expressed in GI mucosa and cancers. In the GI tract, SRF is the central regulator of genes involved in apoptosis, dedifferentiation, proliferation, and migration of cells. Since SRF is the cell phenotypic modulator, it may play an essential role in the development of myopathy, hypertrophy, ulcers, gastric and colon cancers within the GI tract. Given the multi-functional role displayed by SRF in the digestive system, SRF has received more attention emerging as a potential therapeutic target. This review summarizes the findings in SRF research pertaining to the GI tract and provides valuable insight into future directions.

Acute Aerobic Swimming Exercise Induces Distinct Effects in the Contractile Reactivity of Rat Ileum to KCl and Carbachol.

Aerobic exercise promotes short-term physiological changes in the intestinal smooth muscle associated to the ischemia-reperfusion process; however, few studies have demonstrated its effect on the intestinal contractile function. Thus, this work describes our observations regarding the influence of acute aerobic swimming exercise in the contractile reactivity, oxidative stress, and morphology of rat ileum. Wistar rats were divided into sedentary (SED) and acutely exercised (EX-AC) groups. Animals were acclimated by 10, 10, and 30 min of swimming exercise in intercalated days 1 week before exercise. Then they were submitted to forced swimming for 1 h with a metal of 3% of their body weight attached to their body. Animals were euthanized immediately after the exercise section and the ileum was suspended in organ baths for monitoring isotonic contractions. The analysis of lipid peroxidation was performed in order to determinate the malondialdehyde (MDA) levels as a marker of oxidative stress, and intestinal smooth muscle morphology by histological staining. Cumulative concentration-response curves to KCl were altered in the EX-AC with an increase in both its efficacy and potency (Emax = 153.2 ± 2.8%, EC50 = 1.3 ± 0.1 × 10−2 M) compared to the SED group (Emax = 100%, EC50 = 1.8 ± 0.1 × 10−2 M). Interestingly, carbachol had its efficacy and potency reduced in the EX-AC (Emax = 67.1 ± 1.4%, EC50 = 9.8 ± 1.4 × 10−7 M) compared to the SED group (Emax = 100%, EC50 = 2.0 ± 0.2 × 10−7 M). The exercise did not alter the MDA levels in the ileum (5.4 ± 0.6 μ mol/mL) in the EX-AC compared to the SED group (8.4 ± 1.7 μ mol/mL). Moreover, neither the circular nor the longitudinal smooth muscle layers thickness were modified by the exercise (66.2 ± 6.0 and 40.2 ± 2.6 μm, respectively), compared to the SED group (61.6 ± 6.4 and 34.8 ± 3.7 μm, respectively). Therefore, the ileum sensitivity to contractile agents is differentially altered by the acute aerobic swimming exercise, without affecting the oxidative stress and the morphology of ileum smooth muscle.

Morphological features of the distal ileum and ceca of the common pigeon (Columba livia)

Background to the study: Common pigeon ( Columba livia ) is widely distributed worldwide and feeds mainly on grains or seeds and insects and small invertebrates. Some studies have demonstrated variations in the morphology and function of avian alimentary tract. Methods: Ten apparently healthy adult common pigeons were examined in this study. Following euthanasia, gross and histological techniques were used to investigate the morphology of the distal ileum and ceca of common pigeon. Results: At the ileo-ceco-rectal junction, the tunica muscularis of the distal ileum exhibited a thickened layer of oblique smooth muscle fibers positioned between the middle circular and outer longitudinal smooth muscle layers. The ceca of the common pigeon were paired, small (approximately 0.33 cm), blind-ended sacs situated at acute angles with the distal ileum. Histologically, each cecum exhibited a lamina propria-submucosa that contained aggregates of lymphocytes and few glandular acini throughout the length of the organ. Conclusion: It was suggested that the ceca of the common pigeon may be important in immunological response of the bird to invasion by antigens while playing some roles in the digestion of food materials. Moreover, the thickened oblique layer of smooth muscle fibers in the wall of the distal ileum may serve to regulate the passage of materials through the ileo-ceco-rectal orifice. Keywords: Cecum, common pigeon, distal ileum, lamina propria‑submucosa, sphincter

Forkhead Box F2 Regulation of Platelet-derived Growth Factor and Myocardin/Serum Response Factor Signaling Is Essential for Intestinal Development

Alterations in the forkhead box F2 gene expression have been reported in numerous pathologies, and Foxf2(-/-) mice are perinatal lethal with multiple malformations; however, molecular mechanisms pertaining to Foxf2 signaling are severely lacking. In this study, Foxf2 requirements in murine smooth muscle cells were examined using a conditional knock-out approach. We generated novel Foxf2-floxed mice, which we bred to smMHC-Cre-eGFP mice to generate a mouse line with Foxf2 deleted specifically from smooth muscle. These mice exhibited growth retardation due to reduced intestinal length as well as inflammation and remodeling of the small intestine. Colons of Tg(smMHC-Cre-eGFP(+/-));Foxf2(-/-) mice had expansion of the myenteric nerve plexus and increased proliferation of smooth muscle cells leading to thickening of the longitudinal smooth muscle layer. Foxf2 deficiency in colonic smooth muscle was associated with increased expression of Foxf1, PDGFa, PDGFb, PDGF receptor α, and myocardin. FOXF2 bound to promoter regions of these genes indicating direct transcriptional regulation. Foxf2 repressed Foxf1 promoter activity in co-transfection experiments. We also show that knockdown of Foxf2 in colonic smooth muscle cells in vitro and in transgenic mice increased myocardin/serum response factor signaling and increased expression of contractile proteins. Foxf2 attenuated myocardin/serum response factor signaling in smooth muscle cells through direct binding to the N-terminal region of myocardin. Our results indicate that Foxf2 signaling in smooth muscle cells is essential for intestinal development and serum response factor signaling.

English

Sections from duodenum, jejunum and ileum of local breeds of goat (Capra hircus) were studied histologically using light and scanning electron microscopy. The wall of goat small intestine is composed of typical layers: lamina epithelialis mucosae, lamina propria, lamina muscularis mucosae, tunica submucosa, tunica muscularis and tunica serosa. Small intestine villi were covered by a simple columnar epithelium with goblet cells and simple tubular glands, the crypts of Lieberkuhn, containing paneth cells were observed between the villi. The presence of mucus was extensive in the duodenum and the number of goblet cells was highest in the duodenum. The lamina propria consisted of loose connective tissue rich in blood and lymphatic vessels. The lamina muscularis mucosa was presented as a thin layer of circular smooth muscle fibers at the base of the crypts. The submucosa consisted of conjunctive tissue containing blood and lymphatic vessels. The tunica muscularis consisted of the typical inner circular layer and outer longitudinal layer of smooth muscle. The tunica serosa was the thin, outermost small intestine layer that consisted of a very small amount of conjunctive tissue covered by mesothelium. The submucosa was devoid of glands in all three small intestine regions. Scanning electron microscopy showed finger shaped villi in the jujenum, tongue shaped in ileum, leave like in duodenum; the villus has corrugated surface. The corrugations are deep, irregular clefts cutting into the side of the villus. The corrugations are scarce in the duodenum, few in jujenum and numerous in ileum. The surface of villi presents the goblet cell orifices. Keywords: goat, intestine

Periodic oscillatory myoelectrical activity in the gut

Introduction: Myoelectrical (ME) activity, including slow waves and spikes, modulate a variety of patterns of intestinal motility. Any abnormality in the generation and propagation of migrating ME complexes leads to uncoordinated contractions of smooth muscle syncytia, responsible for a clinical condition classified as intestinal dysrhythmia. Objectives: To investigate the dynamics of myoelectrical patterns in the wall of the small bowel under normal and pathological conditions. Materials and methods: The study applied a computer model to analyse electromechanical wave phenomena in a functional unit of the gut. The computer model was based on anatomical and physiological data obtained from in vivo and in vitro experiments. During the numerical experiments the spatial distribution and the dynamics of ME patterns, frequencies, velocities and active forces were recorded. Results: Results of numerical experiments revealed periodic oscillatory activity in the longitudinal smooth muscle layer of the organ. This depended on pacemaker settings and intrinsic electrical properties of muscle syncytia. The observed self-sustained ME activity might underlie the pathogenesis of intestinal dysrhythmia. Conclusions: A detailed explanation for the observed event cannot be provided at present. We suggest that the abnormal oscillatory activity of interstitial cells of Cajal and histomorphological arrangements among muscle cells contribute to the outcome. Acknowledgements: Arabian Gulf University for sponsoring the research.