Decoupling from yolk sac is required for extraembryonic tissue spreading in the scuttle fly Megaselia abdita.

Extraembryonic tissues contribute to animal development, which often entails spreading over embryo or yolk. Apart from changes in cell shape, the requirements for this tissue spreading are not well understood. Here, we analyze spreading of the extraembryonic serosa in the scuttle fly Megaselia abdita. The serosa forms from a columnar blastoderm anlage, becomes a squamous epithelium, and eventually spreads over the embryo proper. We describe the dynamics of this process in long-term, whole-embryo time-lapse recordings, demonstrating that free serosa spreading is preceded by a prolonged pause in tissue expansion. Closer examination of this pause reveals mechanical coupling to the underlying yolk sac, which is later released. We find mechanical coupling prolonged and serosa spreading impaired after knockdown of M. abdita Matrix metalloprotease 1. We conclude that tissue-tissue interactions provide a critical functional element to constrain spreading epithelia.

Transserosal migration of enteric neural stem cells: Developing an avian colon model.

BACKGROUND: Stem cell transplantation is a potential therapy for enteric neuropathies, including Hirschsprung disease. Proof-of-principle has been obtained using focal transplants into neonatal mouse colon. The challenge now is to deliver stem cells to a large surface area to reconstruct an enteric nerve plexus. One proposed method is serosal application using a polymer membrane. However, transserosal migration of stem cells has not been demonstrated in mature colon. This study aimed to develop an avian model to demonstrate stem cell migration across the intact serosa of mature colon. METHODS: Hindguts were obtained from E14 quail embryos, transplanted onto E8 chicken chorioallantoic membranes and harvested after 2 and 8 days. Tissues were assessed immunohistologically for apoptosis (caspase-3), maturity (α-SMA), preservation of mucosa (E-cadherin), and preservation of serosa (cytokeratin). RESULTS: Transient necrosis of the central mucosa was observed over the first two days, followed by recovery. Twenty-three grafts were assessed immunohistologically at day 8. Nineteen grafts demonstrated progressive maturation and an intact mucosa. Circumferential serosal preservation was observed in 9 grafts. No apoptosis was seen. CONCLUSION: Avian colon may be successfully harvested with an intact serosa. Large chorioallantoic membrane grafts remain viable for at least 8 days, and the serosa can be preserved throughout. This provides an economical platform for assessing transserosal migration of stem cells in mature colon.

Activation and synchronization of the oscillatory morphodynamics in multicellular monolayer.

Oscillatory morphodynamics provides necessary mechanical cues for many multicellular processes. Owing to their collective nature, these processes require robustly coordinated dynamics of individual cells, which are often separated too distantly to communicate with each other through biomaterial transportation. Although it is known that the mechanical balance generally plays a significant role in the systems' morphologies, it remains elusive whether and how the mechanical components may contribute to the systems' collective morphodynamics. Here, we study the collective oscillations in the Drosophila amnioserosa tissue to elucidate the regulatory roles of the mechanical components. We identify that the tensile stress is the key activator that switches the collective oscillations on and off. This regulatory role is shown analytically using the Hopf bifurcation theory. We find that the physical properties of the tissue boundary are directly responsible for synchronizing the oscillatory intensity and polarity of all inner cells and for orchestrating the spatial oscillation patterns inthe tissue.

High-resolution mapping of gastric slow-wave recovery profiles: biophysical model, methodology, and demonstration of applications.

Slow waves play a central role in coordinating gastric motor activity. High-resolution mapping of extracellular potentials from the stomach provides spatiotemporal detail on normal and dysrhythmic slow-wave patterns. All mapping studies to date have focused exclusively on tissue activation; however, the recovery phase contains vital information on repolarization heterogeneity, the excitable gap, and refractory tail interactions but has not been investigated. Here, we report a method to identify the recovery phase in slow-wave mapping data. We first developed a mathematical model of unipolar extracellular potentials that result from slow-wave propagation. These simulations showed that tissue repolarization in such a signal is defined by the steepest upstroke beyond the activation phase (activation was defined by accepted convention as the steepest downstroke). Next, we mapped slow-wave propagation in anesthetized pigs by recording unipolar extracellular potentials from a high-resolution array of electrodes on the serosal surface. Following the simulation result, a wavelet transform technique was applied to detect repolarization in each signal by finding the maximum positive slope beyond activation. Activation-recovery (ARi) and recovery-activation (RAi) intervals were then computed. We hypothesized that these measurements of recovery profile would differ for slow waves recorded during normal and spatially dysrhythmic propagation. We found that the ARi of normal activity was greater than dysrhythmic activity (5.1 ± 0.8 vs. 3.8 ± 0.7 s; P < 0.05), whereas RAi was lower (9.7 ± 1.3 vs. 12.2 ± 2.5 s; P < 0.05). During normal propagation, RAi and ARi were linearly related with negative unit slope indicating entrainment of the entire mapped region. This relationship was weakened during dysrhythmia (slope: -0.96 ± 0.2 vs -0.71 ± 0.3; P < 0.05).NEW & NOTEWORTHY The theoretical basis of the extracellular gastric slow-wave recovery phase was defined using mathematical modeling. A novel technique utilizing the wavelet transform was developed and validated to detect the extracellular slow-wave recovery phase. In dysrhythmic wavefronts, the activation-to-recovery interval (ARi) was shorter and recovery-to-activation interval (RAi) was longer compared with normal wavefronts. During normal activation, RAi vs. ARi had a slope of -1, whereas the weakening of the slope indicated a dysrhythmic propagation.

Cytomorphometry of serosal effusion in dogs.

Cytomorphometry made on cytological slides is the quantitative method of precise analysis of cellular structures, including both cytoplasm and nucleus. The aim of this study was to describe cytomorphometric parameters of mesothelial cells in the course of benign reactive and malignant proliferation and to compare them to carcinomas and adenocarcinomas located within serosal cavities in dogs. The second aim was to evaluate applicability of cytomorphometry to diagnostics of diseases causing accumulation of effusion in serosal cavities. Cytological samples of normal and non-malignant mesothelium, mesothelioma and various carcinomas were collected from dogs. Cytomorphometry was made on the smears stained with Giemsa solution. Mean nuclear and cellular perimeter, mean nuclear and cellular area, mean nuclear and cellular diameter, and mean nuclear and cellular roundness were determined. Moreover, nuclear to cytoplasmic ratio (N/C) was calculated. The data revealed statistically significant differences for all parameters, excluding mean nuclear perimeter, between compared groups. Normal mesothelium cells and their nuclei were significantly smaller and more elongated than cells and nuclei of both benign reactive and malignant neoplastic mesothelium. Only a few differences were observed between benign reactive mesothelium cells and mesothelioma cells - mean nuclear area and mean nuclear diameter of benign reactive mesothelium cells were significantly larger and N/C ratio was higher in comparison to mesothelioma cells. Even though some significant differences were observed, considerable overlap of these cytomorphometric parameters in animals with different diseases limited practical role of these observations. Cytomorphometric analysis of cellular samples collected from dogs with proliferative processes affecting serosal cavities can be only an auxiliary method increasing accuracy of preoperative diagnosis.

[VISUALIZATION OF THREE-DIMENSIONAL RELIEF STRUCTURES OF SEROUS MEMBRANES WITH A LIGHT MICROSCOPE].

Methods for three-dimensional visualization of histological film preparations were developed using traditional flat-field microscopes. Preliminarily, the structures examined acquired the light reflecting ability by the reduction of silver nitrate impregnating them. Microscopy of preparations is carried out in reflected incident tenebrous illumination. The methods of processing of preparations for the study of cell surface relief, limiting membrane of the mesothelium and subsurface collagen fibers. Preparations are stored and examined in the wet state.

Decrease in Cell Volume Generates Contractile Forces Driving Dorsal Closure.

Biological tissues must generate forces to shape organs and achieve proper development. Such forces often result from the contraction of an apical acto-myosin meshwork. Here we describe an alternative mechanism for tissue contraction, based on individual cell volume change. We show that during Drosophila dorsal closure (DC), a wound healing-related process, the contraction of the amnioserosa (AS) is associated with a major reduction of the volume of its cells, triggered by caspase activation at the onset of the apoptotic program of AS cells. Cell volume decrease results in a contractile force that promotes tissue shrinkage. Estimating mechanical tensions with laser dissection and using 3D biophysical modeling, we show that the cell volume decrease acts together with the contraction of the actin cable surrounding the tissue to govern DC kinetics. Our study identifies a mechanism by which tissues generate forces and movements by modulating individual cell volume during development.

Existence of c-Kit negative cells with ultrastructural features of interstitial cells of Cajal in the subserosal layer of the W/W(v) mutant mouse colon.

Interstitial cells of Cajal (ICC) are mesenchymal cells that are distributed along the gastrointestinal tract and function as pacemaker cells or intermediary cells between nerves and smooth muscle cells. ICC express a receptor tyrosine kinase c-Kit, which is an established marker for ICC. The c-kit gene is allelic with the murine white-spotting locus (W), and some ICC subsets were reported to be missing in heterozygous mutant W/W(v) mice carrying W and W(v) mutated alleles. In this study, the characterization of interstitial cells in the subserosal layer of W/W(v) mice was analyzed by immunohistochemistry and electron microscopy. In the proximal and distal colon of W/W(v) mutant mice, no c-Kit-positive cells were detected in the subserosal layer by immunohistochemistry. By electron microscopy, the interstitial cells, which were characterized by the existence of caveolae, abundant mitochondria and gap junctions, were observed in the W/W(v) mutant colon. The morphological characteristics were comparable to those of the multipolar c-Kit positive ICC seen in the subserosa of proximal and distal colon of wild-type mice. Fibroblasts were also located in the same layers, but the morphology of the fibroblasts was distinguishable from that of ICC in wild type mice or of ICC-like cells in W/W(v) mutant mice. Collectively, it is concluded that c-Kit-negative interstitial cells showing a typical ICC ultrastructure exist in the proximal and distal colon of W/W(v) mutant mice.

Using of immunocytochemistry in differential diagnosis of neoplasms of serosal cavities in dogs.

The presence of tumor within the serosal cavities, often connected with accumulation of serosal effusion, is a quite common problem in the small animal veterinary medicine. The first step in diagnosis of such cases is cytopathological examination. The aim of the present study was to evaluate the usefulness of cytology and immunocytochemistry, using commercially available antibodies (anti-cytokeratin, anti-vimentin, and anti-desmin), in differential diagnosis of malignant tumors located within serosal cavities in dogs. The final cytological diagnosis of carcinoma/adenocarcinoma, sarcoma, and mesothelioma was obtained on the basis of routine cytopathology and immunocytochemistry, and then confirmed by histopathology and immunohistochemistry. Cytoplasmic immunoreactivitiy of normal mesothelid cells and cytoplasmic immunoreactivity of hyperplastic mesothelial cells revealed constant and strong expression of all examined intermediate filaments: cytokeratin, vimentin and desmin. Application of routine cytopathology and immunocytochemistry allowed 32 neoplastic tumors to be detected: 19 cases of carcinomas/adenocarcinomas, 6 cases of sarcomas, 7 cases of mesotheliomas. Immunostaining of cytopathological samples with chosen set of antibodies: anti-cytokeratin, anti-vimentin, anti-desmin is a useful, and low invasive test for differentiation between mesotheliomas and carcinomas/adenocarcinomas in dogs.

Cholera toxin B subunit-binding and ganglioside GM1 immuno-expression are not necessarily correlated in human salivary glands.

OBJECTIVE: To determine and compare the presence and in situ localization of the glycosphingolipid ganglioside GM1 in human salivary glands using the biomarkers for GM1: cholera toxin and antibodies against GM1. MATERIALS AND METHODS: Immunohistochemical analyses were performed on sections of adult human submandibular, parotid and palatinal glands using cholera toxin sub-unit B and two polyclonal antibodies against ganglioside GM1 as biomarkers. RESULTS: Immunofluorescence microscopy showed that the toxin and antibodies were co-localized in some acini but not in others. The cholera toxin mainly reacted with the cell membranes of the mucous acini in the submandibular gland, while incubation with the antibody against GM1 gave rise to a staining of the cytoplasm. The cytoplasm in some secretory acinar cells in the parotid gland was stained by the cholera toxin, whereas only small spots on the plasma membranes reacted with anti-GM1. The plasma membranes in the parotid excretory ducts appeared to react to anti-GM1, but not to cholera toxin. CONCLUSIONS: Cholera toxin induces the expression of ion channels and carriers in the small intestine and increases the production of secretory mucins. Although their mutual immunohistochemical localization may differ, both cholera toxin and ganglioside GM1 are present in the mucin-producing acini from salivary glands. This could point to a relationship between ganglioside expression and production of salivary mucins.

Echography of the cervix and uterus during the proliferative and secretory phases of the menstrual cycle in bonnet monkeys (Macaca radiata).

We undertook the present study to investigate the echographic characteristics of the uterus and cervix of female bonnet monkeys ( Macaca radiata ) during the proliferative and secretory phases of the menstrual cycle. The cervix was tortuous in shape and measured 2.74 ± 0.30 cm (mean ± SD) in width by 3.10 ± 0.32 cm in length. The cervical lumen contained 2 or 3 colliculi, which projected from the cervical canal. The echogenicity of cervix varied during proliferative and secretory phases. The uterus was pyriform in shape (2.46 ± 0.28 cm × 1.45 ± 0.19 cm) and consisted of serosa, myometrium, and endometrium. The endometrium generated a triple-line pattern; the outer and central lines were hyperechogenic, whereas the inner line was hypoechogenic. The endometrium was significantly thicker during the secretory phase (0.69 ± 0.12 cm) than during the proliferative phase (0.43 ± 0.15 cm). Knowledge of the echogenic changes in the female reproductive organs of bonnet monkeys during a regular menstrual cycle may facilitate understanding of other physiologic and pathophysiologic changes.

Immunological screening for tumor cells in serous body fluids has added value with the CELL-DYN Sapphire.

BACKGROUND: Conventional cytological examination has limited sensitivity for detecting tumor cells in serous body cavity effusions and therefore, adjuvant techniques are necessary for a reliable diagnosis. Flow cytometry has proven benefit in these circumstances. The aim of our study was to explore the feasibility of CELL-DYN Sapphire, an advanced hematology analyzer with flow cytometric capabilities, for detecting tumor cells in serous body fluids, using CD326 monoclonal antibodies, which are directed against the epithelial marker EpCAM. METHODS: One hundred and five serous fluids (39 peritoneal and 66 pleural effusions) were analyzed by the CELL-DYN Sapphire using monoclonal antibody combinations CD3/CD19 and CD45/CD326. Of all samples a cytospin preparation was made and microscopically examined; the pathology findings served as a reference. RESULTS: Using a threshold of 1% CD326+ cells, CELL-DYN Sapphire identified nine out of 12 cases with tumor cells in the serous effusions (sensitivity 75%), whereas routine cytology found eight cases (sensitivity 67%). The combination of immunophenotyping and cytology identified all 12 cases with tumor cells in the effusion fluid (sensitivity 100%). The specificities were 92% and 100%, respectively. CONCLUSIONS: We demonstrated that it is feasible to run an immunophenotypic assay on CELL-DYN Sapphire for detecting tumor cells in serous body fluids. In addition, this study confirmed that a combination of conventional cytology and flow cytometry had a very high diagnostic yield in cases of carcinomatous effusions.

Transepithelial D-glucose and D-fructose transport across the American lobster, Homarus americanus, intestine.

Transepithelial transport of dietary D-glucose and d-fructose was examined in the lobster Homarus americanus intestine using D-[(3)H]glucose and D-[(3)H]fructose. Lobster intestines were mounted in a perfusion chamber to determine transepithelial mucosal to serosal (MS) and serosal to mucosal (SM) transport mechanisms of glucose and fructose. Both MS glucose and fructose transport, as functions of luminal sugar concentration, increased in a hyperbolic manner, suggesting the presence of mucosal transport proteins. Phloridizin inhibited the MS flux of glucose, but not that of fructose, suggesting the presence of a sodium-dependent (SGLT1)-like glucose co-transporter. Immunohistochemical analysis, using a goat anti-rabbit GLUT5 polyclonal antibody, revealed the localization of a brush border GLUT5-like fructose transport protein. MS fructose transport was decreased in the presence of mucosal phloretin in warm spring/summer animals, but the same effect was not observed in cold autumn/winter animals, suggesting a seasonal regulation of sugar transporters. Mucosal phloretin had no effect on MS glucose transport. Both SM glucose and SM fructose transport were decreased in the presence of increasing concentrations of serosal phloretin, providing evidence for the presence of a shared serosal GLUT2 transport protein for the two sugars. The transport of d-glucose and d-fructose across lobster intestine is similar to sugar uptake in mammalian intestine, suggesting evolutionarily conserved absorption processes for these solutes.

Cortisol affects tight junction morphology between pavement cells of rainbow trout gills in single-seeded insert culture.

A primary culture system of rainbow trout gill pavement cells grown on permeable support (single-seeded insert, SSI) was used to examine histological and physiological changes induced by the addition of the corticosteroid hormone cortisol. Pavement cell epithelia were cultured under symmetrical conditions (L15 apical/L15 basolateral) and developed a high transepithelial resistance (TER, 6.84 ± 1.99 kΩ cm(2), mean ± SEM) with a low phenol red diffusion rate (PRD, 0.15 ± 0.03 µmol l(-1)/day). Addition of cortisol to the basolateral compartment increased TER twofold and reduced PRD threefold over a 5-day period. A similar increase in TER could be seen after 24 h apical freshwater (FW) in control cultures. In cortisol-treated cultures FW exposure did not change TER, but PRD increased significantly. Histochemical staining of the cytoskeleton of cells in SSI culture revealed a morphological partitioning into a single mucosal layer of polarized, polygonal cells featuring cortical F-actin rings which were comparable to F-actin rings of epithelial cells on the lamellar and filamental surface, and several unorganized serosal layers of cells with F-actin stress fibers. Addition of cortisol increased cell density by 18% and in the mucosal layer it led to smaller, less polygonal cells with increased height and increased cell contact area. In transmission electron microscopic images two pairs of cytoplasmatic electron-dense structures confining the zonula occludens apically and basally toward the zonula adhaerens were found. Addition of cortisol increased the distance between those paired structures, hence led to deeper tight junctions. The cortisol-induced increase in barrier properties, therefore, involves a structural fortification of the tight junctions which was not generally modified by a short 24-h apical freshwater stress. These results identify cortisol as a regulator of tight junction morphology between pavement cells of euryhaline fish such as the trout.

Placenta-like structure of the aphid endoparasitic wasp Aphidius ervi: a strategy of optimal resources acquisition.

Aphidius ervi (Hymenoptera: Braconidae) is an entomophagous parasitoid known to be an effective parasitoid of several aphid species of economic importance. A reduction of its production cost during mass rearing for inundative release is needed to improve its use in biological control of pests. In these contexts, a careful analysis of its entire development phases within its host is needed. This paper shows that this parasitoid has some characteristics in its embryological development rather complex and different from most other reported insects, which can be phylogenetically very close. First, its yolkless egg allows a high fecundity of the female but force them to hatch from the egg shell rapidly to the host hemocoel. An early cellularisation allowing a rapid differentiation of a serosa membrane seems to confirm this hypothesis. The serosa wraps the developing embryo until the first instar larva stage and invades the host tissues by microvilli projections and form a placenta like structure able to divert host resources and allowing nutrition and respiration of embryo. Such interspecific invasion, at the cellular level, recalls mammal's trophoblasts that anchors maternal uterine wall and underlines the high adaptation of A. ervi to develop in the host body.

Microscopy of the koala mandibular (submandibular) glands.

Koala mandibular (submandibular) glands are compound tubuloacinar glands, the secretory units of which consist only of serous cells. Intercellular canaliculi occur between the serous cells, which are continuous with a minute lumen that courses through the centre of each secretory unit. Intercalated ducts are abundant and join striated ducts, the latter being characterized by elaborate basolateral infoldings of the plasmalemma. Secretory granules within the serous cells fail to stain with either the PAS or Alcian Blue (pH 2.5) staining procedures. Ultrastructurally, the secretory granules are membrane bound, and consist of a homogeneous electron lucent material with a fine filamentous texture. The granules tend to coalesce into irregular shaped complexes of secretory material. Discharge of secretory material into the canalicular lumen is a common observation.

Functional vanilloid receptor-1 in human submandibular glands.

Vanilloid receptor-1 (VR1) was originally found in the nervous system. Recent evidence indicates that VR1 is also expressed in various cell types. We hypothesized that VR1 exists in the human submandibular gland (SMG) and is involved in regulating salivary secretion. VR1 mRNA and protein were expressed in human SMGs and a human salivary intercalated duct cell line. VR1 was mainly located in serous acinar and ductal cells, but not in mucous acinar cells. Capsaicin, an agonist of VR1, increased intracellular free calcium, enhanced phosphorylation of extracellular signal-regulated kinase, and induced the trafficking of aquaporin 5 (AQP5) from the cytoplasm to the plasma membrane. These effects were abolished by pre-treatment with the VR1 antagonist capsazepine. Furthermore, capsaicin cream applied to the skin covering the submandibular area increased salivary secretion. These findings indicated that a functional VR1 is expressed in the human SMG and is involved in regulating salivary secretion by mediating AQP5 trafficking.

Cultures of human tracheal gland cells of mucous or serous phenotype.

There are two main epithelial cell types in the secretory tubules of mammalian glands: serous and mucous. The former is believed to secrete predominantly water and antimicrobials, the latter mucins. Primary cultures of human airway gland epithelium have been available for almost 20 yr, but they are poorly differentiated and lack clear features of either serous or mucous cells. In this study, by varying growth supports and media, we have produced cultures from human airway glands that in terms of their ultrastructure and secretory products resemble either mucous or serous cells. Of four types of porous-bottomed insert tested, polycarbonate filters (Transwells) most strongly promoted the mucous phenotype. Coupled with the addition of epidermal growth factor (EGF), this growth support produced "mucous" cells that contained the large electron-lucent granules characteristic of native mucous cells, but lacked the small electron-dense granules characteristic of serous cells. Furthermore, they showed high levels of mucin secretion and low levels of release of lactoferrin and lysozyme (markers of native serous cells). By contrast, growth on polyethylene terephthalate filters (Cyclopore) in medium lacking EGF produced "serous" cells in which small electron-dense granules replaced the electron-lucent ones, and the cells had high levels of lactoferrin and lysozyme but low levels of mucins. Measurements of transepithelial resistance and short-circuit current showed that both "serous" and "mucous" cell cultures possessed tight junctions, had become polarized, and were actively secreting Cl.

Trefoil factor family 3 expression in the oral cavity.

This study examined the expression, in oral keratinocytes and in the major and minor salivary glands, of Trefoil factor family 3 (TFF3) peptide. Trefoil factor family 3 messenger RNA (mRNA) and peptide were detected in cultures of normal oral keratinocytes by quantitative real-time polymerase chain reaction (PCR) and western blotting, respectively. Trefoil factor family 3 was found, by immunohistochemical analyses, to be expressed in the basal layers of the oral mucosal epithelium. In salivary glands, immunohistochemical staining showed that TFF3 peptide expression was strongest in the mucous acini of the submandibular and the small salivary glands. Serous cells in the same glands showed weak staining. In the parotid gland, many serous acini showed weak positive staining, while other areas did not. In all glands examined, the intercalated, striated, and collecting ducts were moderately TFF3-positive. Double immunostaining confirmed that mucous (MUC5B positive) cells were moderately or strongly positive for TFF3 and that some serous (MUC7 positive) cells showed restricted TFF3 expression, mostly in a granular pattern. The prevalence of the TFF3 peptide in the salivary secretions of healthy volunteers was detected by western blotting of saliva from minor salivary glands (four of five) and the parotid gland (one of five) and of mixed submandibular/sublingual saliva (five of five). In conclusion, the submandibular and small salivary glands appear to be the major producers of oral TFF3, but duct cells of all glands and keratinocytes of the oral mucosa may also contribute as sources of TFF3 in the oral cavity.

Characterization of interstitial cells of Cajal in the subserosal layer of the guinea-pig colon.

Interstitial cells of Cajal in the subserosa (ICC-SS) of the guinea-pig proximal colon were studied by immunohistochemistry for c-Kit receptors and by transmission electron microscopy. These cells were distributed within a thin layer of connective tissue space immediately beneath the mesothelium and were multipolar with about five primary cytoplasmic processes that divided further into secondary and tertiary processes to form a two-dimensional network. Ultrastructural observations revealed that ICC-SS were connected to each other via gap junctions. They also formed close contacts and peg-and-socket junctions with smooth muscle cells. Three-dimensional analysis of confocal micrographs revealed that the cytoplasmic processes of ICC-SS had contacts with interstitial cells in the longitudinal muscle layer. Taking account of the location and peculiar arrangement of the ICC-SS and the main functions of the proximal colon, i.e. the absorption and transport of fluids, we suggest that the superficial network of ICC-SS acts as a stretch receptor to detect circumferential expansion and swelling of the colon wall and triggers the contraction of the longitudinal muscle to accelerate the drainage of fluids from the colon.