Outer Circular Muscle Layers Research Articles

Histomorphology of the Adult Digestive Tract of Capnodis tenebrionis (L. 1758) (Coleoptera, Buprestidae).

The morphological and histological structures of the digestive tracts of adult males and females of Capnodis tenebrionis (L. 1758) are described using stereo microscopy, light microscopy, and scanning electron microscopy. C. tenebrionis is an economically important species and not previously studied. The digestive tract of C. tenebrionis is morphologically and histologically divided into three main parts, including foregut, midgut, and hindgut. The foregut begins at the mouth followed by the short pharynx and esophagus, crop and proventriculus. Histologically, the foregut showed outer circular and inner longitudinal muscle layers followed by a basement membrane and epithelium. The innermost layer is intima. The inner surface of the crop shows several spine-like structures. There are clustered teeth on the inner surface of the proventriculus. The midgut consists of outer muscularis and inner columnar epithelium with a peritrophic membrane surrounding gut content. The outer surface of the midgut is covered with regularly spaced rounded structures called regenerative crypts. The Malpighian tubule shows a single layer of cuboidal epithelium. The hindgut, the last part of the digestive system, initiates with pylorus followed by ileum, colon, and rectum and ends exteriorly with the anus.

Comparative muscular morphology in Archinemertea (Nemertea: Palaeonemertea)

Knowledge on the detailed body plan in Palaeonemertea (a group putatively considered to retain ancestral character states within Nemertea) is essential in understanding the morphological evolution among not only nemerteans but also the rest of bilaterians in general; however, such information has been scanty in previous literature. In this study, we examined the body wall musculature, the position of the nervous system, and the musculature of the proboscis apparatus in 14 species of Archinemertea (a palaeonemertean clade comprised of Cephalotrichidae and Cephalotrichellidae) using confocal laser scanning microscopy with phalloidin labeling as well as classical Mallory’s trichrome staining. Unexpectedly, all the archinemerteans possessed a diagonal muscle layer lying directly ‘above’—instead of ‘below’, as usually found in most vermiform animals—the body wall outer circular muscle layer, a character state that has never been reported among Bilateria except for some acoels and proseriates. We speculate that the aberrant position of the outer diagonal muscle layer might have been actualized as a result of a flip-flop in a genetic regulatory circuit that controls the body wall muscular morphogenesis, which must have happened independently among the bilaterian evolution at least once in Acoela (Xenacoelomorpha), Proseriata (Platyhelminthes), and Archinemertea (Nemertea), respectively. Based on available phylogenetic data and the results from the present observation, we reconstructed the evolution of morphological characters within Archinemertea and its subclades. The outer diagonal muscle layer is likely a synapomorphy for Archinemertea (Cephalotrichidae + Cephalotrichellidae). Members of Balionemertes and Cephalotrichella possess some unique states for palaeonemerteans in muscular morphology (muscular strand associated with lateral nerve cord; longitudinal muscles between brain and extraganglionic tissue; proboscis with outer longitudinal muscle strands). We propose that muscle fibers embedded in lateral nerve cords, termed myofibrillae, in hoplo- and heteronemerteans are homologous with the body wall longitudinal muscles near the lateral nerves surrounded by circular muscles.

Expression of Neuron-Specific Enolase and S-100 in the Ileum and Ileocecal Junction in the Human Fetuses at Various Gestational Ages

Background and Objectives: The purpose of this study was to study the histogenesis and neuroanatomy of the human fetal ileum and ileocecal junction at various gestational ages (15, 18, 20, 28, and 32 weeks) using neuron-specific enolase (NSE) as a neuronal marker and S-100 as a glial marker for the enteric nervous system. Materials and Methods: For this study, five aborted normal fetuses were obtained from the fetal repository of Department of Anatomy. The ileocecal part of the small intestine of these fetuses was dissected, processed, and sectioned and stained with hematoxylin and eosin and cresyl violet. Immunohistochemistry was performed using antibodies to NSE and S-100 and observed under a BX61 Olympus microscope using a DP71 camera. Results: The myenteric and submucosal plexuses of terminal ileum and ileocecal junction show immunoreactivity for both NSE and S-100 by 20 weeks. The development of myenteric plexus is more advanced than submucosal plexus. The immature neurons at 15 weeks progressively mature with distinct cell processes at 32 weeks. The mature ileocecal junction is composed of two outer circular muscle layers and a single inner longitudinal muscle layer. At 32 weeks, ileocecal valve was visualized. Interpretation and Conclusions: Our study provides the morphological evidence of the immunoreactivity in the ganglion plexus and the development of ileum and ileocecal junction at different developmental stages. It also substantiates the concept of ileocecal junction being an intussusception of ileum into the cecum.

Redescription of Tubulanus mawsoni (Wheeler 1940) comb. nov. (Palaeonemertea: Tubulanidae) from the Bellingshausen Sea (Antarctica)

Tubulanus mawsoni (Wheeler 1940) comb. nov. is redescribed based on the material collected during the Spanish Antarctic expedition Bentart-03 through the Bellingshausen Sea (Antarctica). Previously belonging to the genus Carinina Hubrecht 1885, the species is transferred to the genus Tubulanus based on the situation of the brain and lateral nerves between the basement membrane and the outer circular muscle layer, the presence of muscle crosses in the body wall, the position of the blood and excretory systems, the presence of proboscis nerves and the structure of the cerebral sensory organs, the rhynchocoel wall and the rhynchodaeal and buccal nerves. Microphotographs of the different regions of the body and the proboscis structure are provided for the first time. Based on the ambiguities between Tubulanus diagnosis and the species descriptions, as well as the possible paraphyletic status of the genus, the need for new morphological and molecular studies is suggested.http://zoobank.org/urn:lsid:zoobank.org:pub:544458B6-F448-4CE4-B0D6-946D78903C86

Oligodendrorhynchus hesperides gen. et sp. n. (Heteronemertea) from the Bellingshausen Sea

Oligodendrorhynchus hesperides gen. et sp. n. (Heteronemertea) from the Bellingshausen Sea A new genus and species of heteronemertean from the Antarctic (Bellingshausen Sea), Oligodendrorhynchus hesperides, is described and illustrated. Some morphological features with major systematic significance are following: the mode of branching of the proboscis and its low number of terminal branches; the lack of horizontal lateral cephalic slits but in their place a pair of shallow epidermal depressions; a gelatinous amorphous connective stratum between the outer longitudinal and circular muscle layers; the presence of a rhynchocoelic nerve; isolated fibres of the rhynchocoel circular muscle layer interwoven with bundles of the adjacent body-wall inner longitudinal muscle fibres in the intestinal region. Other anatomical characters which can also be used to distinguish the new taxon from existing heteronemertean species that have a branched proboscis are also discussed.

Ultrastructure of the sporocysts of Eurytrema coelomaticum (Giard Et Billet, 1892) Looss, 1907

The digenetic trematode Eurytrema coelomaticum is a parasite of pancreatic ducts of ruminants. The ultrastructure of the mother and daughter sporocysts of E. coelomaticum was analyzed. The mother sporocyst was attached to the coelome of the intestine wall of intermediate snail host Bradybaena similaris, intimately adhered in some regions. It presents a highly folded tegument with granules and the body wall was composed by an outer syncitial layer, basal lamina, and circular and longitudinal muscle layer. Below was the cell body (cyton) with the nucleus. The daughter sporocysts obtained by dissection exhibited many granules and secretory vesicle in the outer layer indicating an intense secretory activity. The body wall presented the same layers of the mother sporocysts, but the outer syncitial layer invaginated and an amorphous layer was present between the syncitial and circular muscle layers. The protonephridial excretory system was viewed. The anterior and posterior end of the expelled sporocyst exhibit a degenerated structure, but biological activity still occurred in these regions. The swollen middle of the body was filled by a lamellar structure formed by degenerating membranes, but the excretory system was preserved. The endocyst wall was fibrilar and filled by cercariae and amorphous, membranous and secretory material inside it. These results were discussed.

The action of vasoactive drugs on longitudinal and circular muscle of dog mesenteric vein.

Abstract The dog anterior mesenteric vein has outer longitudinal and inner circular muscle layers. The response of the vein to drugs was recorded without disrupting the muscle arrangements by combining constant-flow perfusion of a segment with isometric recording of longitudinal tension. Noradrenaline and acetylcholine were potent stimulants. Tachyphylaxis developed to histamine, 5-hydroxytryptamine and angiotensin. Cocaine and guanethidine potentiated the responses to noradrenaline and fluorescent microscopy confirmed the presence of adrenergic nerves in both muscle layers. Isoprenaline partially relaxed the stimulated vein and this action was blocked by propranolol. Evidence was obtained which suggests the existence in the vein of specific receptors for several of the agonists investigated.

The Role of Capsaicin in Spontaneous Pacemaking Activity in Gastrointestinal Tract

Interstitial cells of Cajal (ICCs) are the pacemaking cells in the gastrointestinal (GI) tracts that generate the rhythmic oscillations in the membrane potential which were known as slow waves recorded in native smooth muscle tissue preparations in the past. Auto-rhythmicity in GI tracts is an exclusive property of ICCs and the spread of slow waves through GI tracts occurs electrically, and not by the active regeneration properties of ICCs and smooth muscles. Pacemaking ICCs are organized into electrically coupled networks within discrete areas of the stomach, small intestine, and colon.1,2 ICCs were originally identified by Santiago Ramon y Cajal and were characterized by morphological criteria until the discovery that these cells express the receptor tyrosine kinase Kit.3 Subsequent studies determined that Kit immunoreactivity in the muscularis propria of the GI tract is restricted to 2 cell types: mast cells4 and ICCs. Kit-positive ICCs are distributed throughout the GI tract as well as in other smooth muscle tissues.5 All regions of the GI tract contain ICCs but the location within the muscularis propria varies according to region or species.6 In the myenteric plexus region, ICCs form a network between the muscle layers forming a mesh around the ganglia and are considered as major pacemaker cells. A network of deep muscular plexus ICCs is present in the small intestine between the inner and outer circular muscle layers.6 In the colon and parts of the gastric antrum, submuscular ICCs are located outside the circular muscle layer.7 Intramuscular ICCs are distributed through the longitudinal and circular muscle layers and are considered to be involved in neurotransmission from nerve terminals. Septal ICCs are found between the fascicles of muscle in humans and other large species. These can be considered as one type of intramuscular ICCs.8 Stellate, subserosal ICCs are observed on the boundary between the longitudinal muscle and the serosa in the colon of mice.9 Capsaicin (8-methyl-N-vanillyl-6-ninenamide) activates afferent fiber endings and capsaicin sensitive primary afferent neurons participate in the regulation of GI motility.10 Furthermore, capsaicin induces contraction in the guinea-pig ileum11 and relaxation in human small and large intestines.10 Namely, it is known that capsaicin may have excitatory action on animal GI motility but inhibitory on human. However, information about the effect of capsaicin on human GI motility is somewhat controversial. Some reports showed the oral administration of capsaicin to fail in showing a significant effect on GI motility in human12-14 but there are reports that capsaicin could contribute to protection of the esophagus and could promote retention of the irritant in the stomach and faster transit through the small bowel.15 However, there are no reports on the direct effect of the capsaicin on ICCs that have important roles for regulation of GI motility as pacemaker cells. In this issue of the Journal of Neurogastroenterology and Motility, Choi et al examined the role of capsaicin on ICC in mouse small intestine. They showed that capsaicin inhibited the pacemaker activity of ICC dose-dependently. The effect of capsaicin, however, is not through the transient receptor potential of the vanilloid type 1 (TRPV1) channel because capsazepine did not block the effect of capsaicin. Consistently with this result, they also showed in their previous study that TRPV1-immunopositive cells were not co-localized with c-Kit positive tissue layer.16 The effect of capsaicin was not through nitric oxide release from ICCs, because there was no influence on capsaicin-induced action by L-NAME, an inhibitor of nitric oxide synthase in their study. Choi et al. proposed that further studies are needed to investigate the direct effect of capsaicin on pacemaker ion channels like TRPC4 or TRPM7 responsible for pacemaking activity in ICCs.17 Interestingly, when the action of capsaicin was examined in the intracellular calcium oscillation, capsaicin completely abolished the calcium oscillation in ICCs. Recently, 3 research groups showed simultaneously the calcium activated Cl channels to be required for pacemaking activity using TMEM16A knockout mice.18-20 Capsaicin might inhibit pacemaking activity of ICCs through the decreased activity of calcium activated Cl channels due to completely abolished calcium oscillations by application of capsaicin to ICCs. The effect of capsaicin seems more complicated because capsaicin acts on ICCs as well as afferent nerve endings of GI tract. In the future, more sophisticated studies are needed to clarify the role of capsaicin in GI tract considering ICCs and species differences.

Unique contractile and structural protein expression in dog ileal inner circular smooth muscle

This study was designed to test the hypothesis that there is heterogeneous expression of contractile and structural proteins between the smooth muscle cells (SMCs) in the inner and outer circular muscle (ICM and OCM) layers of the ileum. Immunohistochemical staining and quantitation of fresh frozen sections of the dog ileum was performed using protein specific antibodies. Smooth muscle (SM) SMA myosin heavy chain (MHC), alpha- and gamma-SM actin, and vinculin all show greater expression in the ICM relative to the OCM. SMB MHC and fibronectin show the opposite pattern, with greater expression in the OCM relative to the ICM. Differences in expression of these proteins are consistent with proposed differences in function of these muscle layers. Hypotheses regarding muscle tone and the coordination and regulation of peristalsis via these different muscle layers based on this data can now be made and tested.

Impact of caveolin-1 knockout on NANC relaxation in circular muscles of the mouse small intestine compared with longitudinal muscles

Recently, we showed that caveolin-1 (cav1) knockout mice (Cav1(-/-) mice) have impaired nitric oxide (NO) function in the longitudinal muscle (LM) layer of the small intestine. The defect was a reduced responsiveness of the muscles to NO compensated by an increase in the function of apamin-sensitive, nonadrenergic, noncholinergic (NANC) mediators. In the present study, we examined similarly the effects of cav1 knockout on the relaxation in circular muscle (CM) of the mouse small intestine. CM of Cav1(-/-) mice also showed defective NO function, but less than in LM, as well as more activation of apamin-sensitive NANC mediators. CM of Cav1(-/-) mice, like LM, lacked cav1 but retained small amounts of cav3 and caveolae in the outer CM layer. In addition, we also examined the effects of a soluble guanylate cyclase inhibitor, 1H-[1,2,4]oxadiazolo-[4,3-alpha]quinazolin-1-one (ODQ), on electric field stimulation (EFS)-mediated relaxation in both LM and CM. ODQ had an effect similar to the block of NO synthesis. Moreover, we compared the actions of two NO donors in the LM and CM of control and Cav1(-/-) mice. Similar to LM, CM of Cav1(-/-) mice showed a reduced responsiveness to the NO donors sodium nitroprusside and S-nitroso-N-acetyl penicillamine. However, both ODQ and apamin blocked the inhibitory effects of the NO donors in LM, whereas apamin had no effect in CM. In conclusion, cav1 knockout affects NO function in both LM and CM, but its effects in CM differ significantly.

Changes in Interstitial Cells of Cajal at the Deep Muscular Plexus Are Associated with Loss of Distention-Induced Burst-Type Muscle Activity in Mice Infected by Trichinella spiralis

The physiology and pathophysiology of the network of interstitial cells of Cajal associated with the deep muscular plexus (ICC-DMP) of the small intestine are still poorly understood. The objectives of the present study were to evaluate the effects of inflammation associated with Trichinella spiralis infection on the ICC-DMP and to correlate loss of function with structural changes in these cells and associated structures. We used immunohistochemistry, electron microscopy, and assessment of distention-inducing electrophysiological parameters in vitro. Damage to ICC-DMP was associated with a loss of distention-induced patterns of electrical activity normally associated with distention-induced peristalsis. Consistently, the timing of recovery of ICC-DMP paralleled the timing of recovery of the distention-induced activity. Nerve varicosities associated with ICC-DMP including cholinergic nerves, assessed by immunoelectron microscopy and whole mount double labeling, paralleled injury to ICC-DMP thus contributing to impaired excitatory innervation of smooth muscle cells. Major additional changes included a remodeling of the inner circular muscle layer, which may affect long-term sensitivity to distention after infection. In conclusion, transient injury to ICC-DMP in response to T. spiralis infection is severe and associated with a complete lack of distention-induced burst-type muscle activity.

Renal and hepatic distribution of type I and type III iodothyronine deiodinase protein in chicken.

Iodothyronine deiodinase in vitro activity studies in the chicken showed the presence of type I and type III iodothyronine deiodinase activity in both liver and kidney. Due to the lack of a specific antiserum the cellular localization of the deiodinase proteins could not be revealed until now. In the present study, specific antisera were used to study the renal and hepatic distribution of type I and type III iodothyronine deiodinase protein in the chicken. Immunocytochemical staining of liver tissue led to an immunopositive signal in the hepatocytes in general. Moreover, a zonal distribution could be detected for both enzymes. Maximum protein expression was shown in a thin layer of hepatocytes bordering the blood veins. Although pericentral localization of type I deiodinase protein has been previously reported in the rat, no data were given concerning type III deiodinase protein. In the present study, we report the co-localization of both enzymes in the chicken. Co-expression of the deiodinases was also found in the kidney. Expression of both proteins was associated with the tubular epithelial cells and with the transitional epithelium, and the inner longitudinal and outer circular muscle layers of the ureter. No staining could be detected in the lamina propria or in the fat tissue surrounding the ureter.

Lack of the complete circular rhabdosphincter and a distinct circular smooth muscle layer around the proximal urethra in elderly Japanese women: an anatomical study.

Histological observations of semiserial sections obtained from the cadavers of 30 elderly Japanese women (aged 61-93 years) found that the urethral rhabdosphincter (URS) usually occurred as a ventrally localized structure instead of exhibiting the normal completely circular configuration. The superoinferior length, thickness and muscle fiber density of the URS area showed significant interindividual variation. A thick fascicle, extending posterolaterally from the URS and radiating to the lateral vaginal wall and other perineal tissues, was usually observed. A circular smooth muscle layer, which immediately surrounded the longitudinal smooth muscle layer, was consistently present in the proximal urethral but not in the bladder neck. These findings suggest that voluntary sphincteric action is weak or incomplete in elderly Japanese women. We therefore hypothesize that upward retraction of the midurethra by the URS, compression of the distal urethra by its posterolateral extensions, and tonus provided by the outer circular smooth muscle layer all contribute to maintaining continence in these women.

Coupling and innervation patterns of interstitial cells of Cajal in the deep muscular plexus of the guinea-pig.

Interstitial cells in the deep muscular plexus (ICC-DMP) are thought to be essential for neurotransmission in the circular muscle. There is evidence for gap junctions within the ICC-DMP network and between ICC-DMP and muscle cells; however, there is no evidence for functional coupling via these gap junctions. In addition, the innervation of individual ICC-DMP has not been studied. We investigated these questions by injecting the dye Lucifer yellow into ICC-DMP of guinea-pig ileum. Nerves were labelled immunohistochemically for protein gene product 9.5. Cells were imaged by confocal microscopy. Most (79%) of the dye-injected ICC-DMP were coupled to one to five other ICC-DMP, and 86% of them were coupled to one to five circular muscle cells. Octanol effectively blocked all coupling. Incubation in pH 6.8-7.0 reduced ICC-ICC coupling to 49% and ICC-muscle coupling to 32%. In contrast, pH 7.8-7.9 increased ICC-ICC and ICC-muscle coupling to 100%. Most ICC somata (95%) and processes (60%) were in close proximity with both nerve fibres and smooth muscle cells. These results provide direct evidence for functional coupling within the ICC-DMP network, and between this network and cells of the outer circular muscle layer and showed that coupling can be affected by pH.

Identification of c-kit-positive cells in the mouse ureter: the interstitial cells of Cajal of the urinary tract.

The existence of a pacemaker system in the urinary tract capable of orchestrating the movement of filtrated urine from the ureteral pelvis to the distal ureter and lower urinary tract seems intuitive. The coordinated activity necessary for such movement or "peristalsis" would likely require an intricate network of cells with pacemaker-like activity, as is the case with the interstitial cells of Cajal (ICC) of the gut. We investigated whether these putative pacemaker cells of the urinary tract are antigenically similar to ICC of the gut by using immunofluorescence staining for c-kit, a cell-surface marker specific for ICC. Ureteral, urinary bladder, and urethral tissues were harvested from female mice of the WBB6F1 strain, and fixed sections were prepared and stained for c-kit. Cell networks composed of stellate-appearing, c-kit-positive, ICC-like cells were found in the lamina propria and at the interface of the inner longitudinal and outer circular muscle layers of the ureteral pelvis but not in the urinary bladder or urethra. Thus, like in the gut, c-kit-positive, ICC-like cells are present in the urinary tract but appear to be restricted to the proximal ureter of this murine species.

On the anatomy and taxonomy ofTubulanus lutescensn.sp. (Nemertini) from the West Coast of Sweden

Abstract A new species of palaeonemertine from the Swedish west coast, Tubulanus lutescens n. sp., is described and illustrated. The species is characterized by, inter alia, rather well developed cerebral sensory organs, abundant frontal glands and an upper as well as a lower dorsal nerve. There are no lateral sensory organs, excretory organs, rhynchocoel vessels or dorsal and ventral muscle crosses between the outer circular and inner circular body wall muscle layers. The functional morphology of the foregut is discussed.

P2X 2 receptor expression by interstitial cells of Cajal in vas deferens implicated in semen emission

Male reproduction is dependent upon seminal emission mediated by vas deferens contraction. This drives spermatic fluid to the prostatic urethra during ejaculation. We localize interstitial cells of Cajal (ICC), which express P2X 2 receptor, subunits of ATP-gated ion channels, to rat, mouse and guinea-pig vas deferens submucosa. Reverse transcription-polymerase chain reaction (RT-PCR) analysis of rat vas deferens resolved two functional splice variant transcripts of the P2X 2 receptor subunit. The P2X 2 receptor mRNA was localized principally within the lamina propria (submucosal) region of the rat vas deferens using in situ hybridization (ISH) and in situ RT-PCR-ISH. Immunohistochemistry using rat, mouse and guinea-pig vas deferens tissues confirmed expression of P2X 2 receptor protein within the lamina propria, particularly within a dense column of small spindle-shaped cells adjacent to the columnar epithelial cells which line the lumen. This immunoreactivity was co-localized with neurone-specific enolase (NSE) and c-Kit protein expression, gene markers for ICC. Mucosal mast cells were distinguished from ICC by toluidine blue staining. Choline acetyltransferase immunoreactivity, a marker for post-ganglionic parasympathetic innervation, occurred on the lateral margin of the lamina propria and extended into the inner longitudinal muscle layer. P2X 1 receptor immunolabelling was associated with sympathetic innervation of the smooth muscle in the outer longitudinal and circular muscle layers, but not the inner longitudinal layer. The physiological significance of the vas deferens ICC which express P2X 2 receptors remains to be established. Possible roles include regulation of smooth muscle activity or mucosal secretion utilizing local ATP signaling, both of which would affect semen transport.

Intimate relationship between interstitial cells of cajal and enteric nerves in the guinea-pig small intestine.

Recent studies have suggested that enteric inhibitory neurotransmission is mediated via interstitial cells of Cajal in some gastrointestinal tissues. This study describes the physical relationships between enteric neurons and interstitial cells of Cajal in the deep muscular plexus (IC-DMP) of the guinea-pig small intestine. c-Kit and vimentin were colocalized in the cell bodies and fine cellular processes of interstitial cells of the deep muscular plexus. Anti-vimentin antibodies were subsequently used to examine the relationships of interstitial cells with inhibitory motor neurons (as identified by nitric oxide synthase-like immunoreactivity) and excitatory motor neurons (using substance P-like immunoreactivity). Neurons with nitric oxide synthase- and substance P-like immunoreactivities were closely associated with the cell bodies of interstitial cells and ramified along their processes for distances greater than 300 micrometer. With transmission electron microscopy, we noted close relationships between interstitial cells and the nitric oxide synthase- and substance P-like immunoreactive axonal varicosities. Varicosities of nitric oxide synthase and substance P neurons were found as close as 20 and 25 nm from interstitial cells, respectively. Specialized junctions with increased electron density of pre- and postsynaptic membranes were observed at close contact points between nitric oxide synthase- and substance P-like immunoreactive neurons and interstitial cells. Close structural relationships (approximately 25 nm) were also occasionally observed between either nitric oxide synthase- and substance P-like immunoreactive varicosities and smooth muscle cells of the outer circular muscle layer. The data suggest that interstitial cells in the deep muscle plexus are heavily innervated by excitatory and inhibitory enteric motor neurons. Thus, these interstitial cells may provide an important, but probably not exclusive, pathway for nerve-muscle communication in the small intestine.

The deep muscular plexus of the pig duodenum: A histochemical and ultrastructural study with special reference to the interstitial cells

The aim of the present study was to describe the deep muscular plexus of the pig duodenum and to characterize its cellular components. Numerous nerve varicosities have been detected in the deep muscular plexus using anti-synaptophysin antibodies. Nerve fibres were also detected here in the outer circular muscle layer, whereas no nerve fibres were observed in the inner circular muscle layer. In the deep muscular plexus, nerve fibres projected to interstitial cells which were characterized at the ultrastructural level. The interstitial cells were of two kinds: the interstitial fibroblastic-like cells (FLC) and the interstitial dense cells (IDC), both of which were interposed between nerve fibres and smooth muscle cells. The FLC were characterized by their elongated bipolar shape, the lack of basal lamina, a well-developed endoplasmic reticulum, a Golgi apparatus, and intermediate filaments. They were closely apposed to axon terminals containing small clear synaptic vesicles and/or dense-cored vesicles. They were frequently connected to each other and to smooth muscle cells of the inner and outer circular layer by desmosomes and more rarely by gap junctions. The IDC are myoid-like cells. They had a stellate appearance and were characterized by a dense cell body, numerous caveolae, and a discontinuous basal lamina. The IDC were always closely apposed to nerve fibres and were connected to smooth muscle cells by desmosomes and small gap junctions. The present results show the unique pattern of cellular organization of the deep muscular plexus of the pig small intestine. They suggest that the interstitial cells in the deep muscular plexus are involved in the integration and transmission of nervous inputs from myenteric neurons to the inner and outer circular muscle layers. The clear-cut distinction observed here between the two types of interstitial cells (fibroblastic- and myoid-like) suggests that the interstitial cells of each type may also be involved in some other specific activity, which still remains to be determined.

Pregnancy outcome and weight gain recommendations for the morbidly obese woman

To examine the anatomic identity of sonographically visible sphincteric structures of the female urethra. The urethra, urinary bladder, and vagina were removed from 11 fresh female cadavers and placed in a water bath. Intraurethral ultrasound was performed with a 360 degrees-rotating 7.5-MHz ultrasound probe. Afterward, the specimens were fixed and cross sections were made transverse to the urethral axis at 5-mm intervals. Corresponding ultrasonograms and histologic images were matched and depicted simultaneously side by side. The anatomic identity of sonographically visible structures was determined by histologic examination and thickness of the longitudinal smooth urethral sphincter measured. Structures visible sonographically were the striated and smooth urethral sphincter muscle layers, vagina, and blood vessels with diameters exceeding 0.2 mm. The longitudinal smooth muscle layer appeared as a well-defined internal hypoechoic ring. The outer circular smooth muscle layers and the striated muscle layers were a more irregular and hyperechoic zone. The circular smooth muscle layers and the striated sphincter muscle layers could not always be differentiated easily. With formalin fixation, tissue shrinkage resulted in a smaller thickness of the longitudinal smooth muscle measured on the histologic specimen. With intraurethral ultrasound, the longitudinal smooth muscle layer appears as a well-defined and measurable hypoechoic ring. The region of the circular smooth muscle and the striated muscle emerges as a hyperechoic and less definable outer zone.