Myenteric Area Research Articles

Anoctamin 1 and c-Kit immunohistochemical study of interstitial cells of Cajal in the muscularis externa of human gastrointestinal tract.

Interstitial cells of Cajal (ICC) are widely distributed in human gastrointestinal (GI) tract, especially in the layer of muscularis externa between neurons and smooth muscles. They play a very important role of coordination of GI tract motility. The aims of this research were to study the morphology and distribution of ICC in the muscularis externa of the GI tract, using immunohistochemistry staining methods, to determine the distribution of immune reactivity of anoctamin 1 (Ano1) compared with c-Kit, and to determine if Ano1 is a reliable marker for ICC in human GI tract. Specimens from the wall of stomach, small intestine, and colon were taken from human cadavers and processed for histological and immunohistochemical study using c-Kit and Ano1 primary antibodies. Interstitial cells of Cajal appeared as bipolar cells, not forming network, in both the circular and longitudinal muscle layers, while in the myenteric area they appeared as multipolar interconnected cells. They were unevenly distributed in and between the muscle layers of the muscularis externa of human GI tract. They were more numerous in the stomach followed by the colon then the small intestine, and more numerous in the myenteric area followed by the circular muscle layer then the longitudinal muscle layer, in the three organs. Our results also showed that Ano1 is a more reliable marker for human ICC than c-Kit. Interstitial cells of Cajal differed in morphology and were unevenly distributed between muscle layers of muscularis externa and between different parts of human GI tract.

An assessment of enteric nervous system and estroprogestinic receptors in obstructed defecation associated with rectal intussusception

The pathophysiological basis of obstructed defecation (OD) is still incompletely understood. In particular, few or no data are available concerning the enteric nervous system (ENS) in this condition. We investigated ENS abnormalities in patients with OD, undergoing surgery, together with the presence of estrogen (α and β) and progesterone receptors, and compare the results with those obtained in controls. Full-thickness rectal samples were obtained from 17 patients undergoing stapled transanal rectal resection for OD associated with rectal intussusception. Samples were analyzed by immunohistochemistry for enteric neurons, enteric glial cells, interstitial cells of Cajal (ICC), and for estrogen and progesterone receptors. Data were compared with those obtained in 10 controls. No differences between patients and controls were found for enteric neurons, whereas (compared with controls) OD patients displayed a significant decrease of enteric glial cells in both the submucous (P = 0.0006) and the myenteric (P < 0.0001) plexus. ICC were significantly increased in patients in the submucosal surface (P < 0.0001) and the myenteric area (P < 0.0001). Concerning estroprogestinic receptors, both were present on ICC in patients and controls. Estrogen receptors α and progesterone receptors were absent on enteric neurons and enteric glial cells in patients and controls, whereas estrogen receptors β were present in all controls and in 69% of patients' enteric neurons (P = 0.18) and in 12% of patients' glial cells (P = 0.0001). Patients with OD associated to rectal intussusception display abnormalities of the ENS and of estrogen receptors β.

Regional Distribution of Interstitial Cells of Cajal (ICC) in Human Stomach

We elucidated the distribution of interstitial cells of Cajal (ICC) in human stomach, using cryosection and c-Kit immunohistochemistry to identify c-Kit positive ICC. Before c-Kit staining, we routinely used hematoxylin and eosin (HE) staining to identify every structure of human stomach, from mucosa to longitudinal muscle. HE staining revealed that the fundus greater curvature (GC) had prominent oblique muscle layer, and c-Kit immunostaining c-Kit positive ICC cells were found to have typical morphology of dense fusiform cell body with multiple processes protruding from the central cell body. In particular, we could observe dense processes and ramifications of ICC in myenteric area and longitudinal muscle layer of corpus GC. Interestingly, c-Kit positive ICC-like cells which had morphology very similar to ICC were found in gastric mucosa. We could not find any significant difference in the distribution of ICC between fundus and corpus, except for submucosa where the density of ICC was much higher in gastric fundus than corpus. Furthermore, there was no significant difference in the density of ICC between each area of fundus and corpus, except for muscularis mucosa. Finally, we also found similar distribution of ICC in normal and cancerous tissue obtained from a patient who underwent pancreotomy and gastrectomy. In conclusion, ICC was found ubiquitously in human stomach and the density of ICC was significantly lower in the muscularis mucosa of both fundus/corpus and higher in the submucosa of gastric fundus than corpus.

Distribution and ultrastructure of interstitial cells of Cajal in the mouse colon, using antibodies to Kit and Kit(W-lacZ) mice.

The roles of the interstitial cells of Cajal in the stomach and intestine are becoming increasingly clear. Interstitial cells of Cajal in the colon are less well known, however. We studied the development and distribution of the interstitial cells of Cajal in the mouse colon, using the tyrosine kinase receptor Kit as a marker. Sections and whole mounts were studied by confocal microscopy after double immunofluorescence with specific antibodies. The ultrastructure of Kit-expressing cells was examined by electron microcopy in KitW-lacz/+ transgenic mice, which carry the lacz gene inserted in place of the first exon of the Kit gene. In the subserosa, the interstitial cells of Cajal formed a two-dimensional plexus. In the myenteric area, the interstitial cells of Cajal formed a dense plexus that gradually merged with the interstitial cells of Cajal in the outer half of the circular muscle. The inner half of the circular layer was devoid of interstitial cells of Cajal whereas in the submuscular region the interstitial cells of Cajal formed a two-dimensional plexus. Tertiary nerves with various chemical codings closely followed interstitial cell of Cajal processes. By electron microscopy, Kit-expressing cells in the outer parts of the musculature had scattered caveolae, inconspicuous basal lamina and numerous mitochondria, whereas in the submuscular region they had more pronounced myoid features. Kit-expressing cells in the mouse colon are identifiable as interstitial cells of Cajal by their ultrastructure. The interstitial cells of Cajal in the mouse colon mature postnatally. They are organized into a characteristic plexus, close to the nerves with various chemical codings.

Ultrastructural study of relationships between c-kit immunoreactive interstitial cells and other cellular elements in the human colon.

C-kit immunocytochemistry was performed on ultrathin sections of human distal colon. Our attention was focused on relationships between c-kit immunoreactive interstitial cells (c-kit ICs) and muscular cells and nervous elements located in the external muscular layers of the colonic wall. C-kit ICs established membrane apposition with both nerve fibers and smooth muscle cells of, respectively, the longitudinal and circular muscle layers, the myenteric area, and the extremus submucosus plexus. C-kit ICs also surrounded the external submucosus plexus and established membrane appositions with nerve elements located inside the myenteric ganglia. These membrane appositions were observed either at the level of the c-kit IC bodies or at that of their cytoplasmic processes. In some cases, membrane appositions were observed concomitantly between the c-kit ICs, nerve fibers, and smooth muscle cells. In all the regions studied, the c-kit ICs were also found to be located in the close vicinity of blood vessels and to have established close contacts with non-immunoreactive fibroblast-like cells. The results of the present study shed essential light on the relationships of c-kit ICs with the neighboring muscle cells and nerve elements, and confirm that the intercalated c-kit ICs well fit with the so-called "interstitial cells of Cajal".

Intestinal pseudo-obstruction and acute pandysautonomia associated with Epstein-Barr virus infection

We report the association of neurological and intestinal disorders with the reactivation of Epstein-Barr virus (EBV) in a child. This previously healthy 13-yr-old boy presented with pharyngitis and acute abdominal ileus. Laparotomy excluded a mechanical obstruction. Postoperatively, he suffered from prolonged intestinal obstruction, pandysautonomia, and encephalomyelitis. Histological examination of the appendix and a rectal biopsy taken 3 months after the onset showed an absence of ganglion cells (appendix) and hypoganglionosis (rectum), with a mononucleate inflammatory infiltrate in close contact with the myenteric neural plexuses. EBV-PCR was positive in the blood and cerebrospinal fluid, and in situ hybridization with the Epstein-Barr virus encoded RNA probe showed positive cells throughout the appendix wall including the myenteric area, in a mesenteric lymph node, and in the gastric biopsies. EBV spontaneous lymphocytic proliferation was noted in the blood. The serology for EBV showed previous infection but antiearly antigen antibodies were present. No immunodeficiency was found. Neurological and GI recovery occurred after 6 months of parenteral nutrition and bethanechol. The omnipresence of EBV associated with the neurointestinal symptoms suggest that the virus was the causal agent. This is the first documented case of acquired hypoganglionnosis due to EBV reactivation.

Interstitial cells of Cajal and nerves in mouse colon, studies of kit expression and neurochemical conding by confocal and electron microscopy

Interstitial cells of Cajal (ICC) are important regulatory cells in the gastrointestinal tract. We studied the distribution and ultrastructure of Kitexpressing ICC and their relationship with nerves in the adult mouse colon. Wholemounts were studied by confocal microscopy after double immunofluorescence with antibodies for Kit together with antibodies raised against either the pan-neuronal marker PGP9.5, or the neuronal NO Synthase or one of the following neuropeptides: VIP, SP, NPY, Leuor Metenkephalines. Transgenic mice carrying a lacZ reporter gene inserted in place of the first exon of the Kit gene (WlacZ/+ heterozygous mice) [1] and controls (+/+) were studied by electron microscopy after beta-galactosidase histochemistry to determine the ultrastructure of Kit expressing ceils. In the subserosa, ICC formed a 2-dimensional plexus accompanied by few nerve fibres. In the myenteric area, the ICC plexus was well-developed, especially close to ganglia and primary nerve fascicles. Tertiary nerves with various chemical coding closely followed ICC processes. The myenteric ICC plexus gradually merged with ICC in the outer half of the circular layer. These ICC had their longest axis in the direction of the circular muscle cells while forming a 3-dimensional network. The inner half of the circular muscle was devoid of ICC processes. An extensive 2-dimensional plexus of ICC and nerves was revealed in the submuscular region. These ICC had their longest axis in the circular direction while multiple processes at right angles connected them in the longitudinal direction. They were also closely followed by nerves with various chemical coding. By electron microscopy, Kitexpressing cells revealed scattered caveolae, incomplete basal lamina and many small mitochondria. Kit-expressing ICC in the mouse colon are organised into several characteristic plexus. Moreover, ICC are in close contact with nerves with different chemical coding. Altogether, Kit-expressing cells in the mouse colon are identifiable as ICC by their ultrastructure. [1] Bernex F et al. Development 1996; 122: 3023-33.

Ultrastructural relationships of spinal primary afferent fibres with neuronal and non-neuronal cells in the myenteric plexus of the cat oesophago-gastric junction

Spinal primary afferent fibres innervating the myenteric area in the oesophago-gastric junction of the cat were selectively labelled by anterogradely transported cholera toxin B subunit–horseradish peroxidase conjugate injected into thoracic dorsal root ganglia. The ultrastructure of these labelled primary afferent fibres was studied in order to determine whether they display close relationships with specific cell types in the myenteric plexus. Horseradish peroxidase was revealed with tetramethylbenzidine stabilized with ammonium heptamolybdate or with the tetramethylbenzidine/tungstate reaction in order to visualize the cytoplasmic organelles and the axolemma, respectively. The labelled primary afferent fibres were unmyelinated. Two kinds of profiles of labelled fibres containing vesicles and mitochondrial accumulations were found: (i) fibres running in myenteric connectives in isolated nerve bundles, and (ii) fibres within the myenteric ganglia. The first kind had small areas of axolemma with no glial cell covering, whereas the second kind had little or no glial cell covering (termed naked primary afferent fibres). In addition, labelled fibres containing few vesicles and mitochondria and running in nerve bundles surrounded by perineurium were numerous. Within the myenteric ganglia, naked primary afferent fibres contacted myenteric neurons. The contacts were mainly axosomatic. No synaptic specializations were distinguished. In the interganglionic area, some labelled fibres terminated close to blood vessels. The intraganglionic naked primary afferent fibres are suggested to be mechanoreceptors. Their exposed axolemma might allow both mechanotransduction and release of neurotransmitters which could act on myenteric neurons. Because they are protected by their glial cell sheath and by bundles of collagen fibrils, interganglionic primary afferent fibres are likely to be less exposed to deformation.

Morphological relationships of choleragenoid horseradish peroxidase‐labeled spinal primary afferents with myenteric ganglia and mucosal associated lymphoid tissue in the cat esophagogastric junction

The goal of the present study was to gain insight into the environmental factors influencing the activity of primary spinal afferent fibers in the different layers of the esophagogastric junction of the cat and, thus, to analyze the relationships of these afferents with various cellular components. Spinal primary afferent fibers were selectively labeled by anterogradely transported choleragenoid horseradish peroxidase conjugate (B-HRP). B-HRP was injected into the thoracic dorsal root ganglion at the T8-T13 levels. 6-Hydroxydopamine-induced sympathectomy was performed prior to B-HRP injection in order to prevent otherwise unavoidable labeling of sympathetic fibers in the gut wall. Numerous labeled fibers ran between, around, and within the myenteric ganglia. Others crossed the muscle layers directly and entered the mucosa, where some ran near granulocytes and around or through solitary lymphoid follicles. Labeled fibers were observed in the squamous esophageal epithelium but not in the fundic glandular epithelium. The fibers in the myenteric area are probably connected to the muscular tension receptors that have been detected by electrophysiologic techniques. This assumption is based on the observation that only a few fibers appear to terminate in muscle layers and on the fact that the myenteric area is very narrow and subject to powerful forces. Fibers in the myenteric ganglia could be involved in local efferent functions. Fibers in the mucosa could act as nociceptors and might be involved in local immunological responses.