Добірка наукової літератури з теми "Mucus externe"

The morphology and the histochemistry from the mucus of the posterior esophagus of the winter flounder and the yellowtail flounder were examined using light and electron microscopy. The esophageal mucosa of both species was organized into elaborate branching folds. The epithelium consisted of a stratified layer of cuboidal cells interspersed with mucus-producing goblet cells. The cuboidal cells in the surface layer also exhibited a secretory function and were characterized by Golgi-associated granules and apical micoridges. These cells were termed esophageal surface secreting cells (ESSCs). The granules of the winter flounder ESSCs were ultrastructurally similar to mucous granules, whereas those of the yellowtail flounder were reminiscent of serous granules. Both types were analogous to those associated with salivary glands in mammals. Both goblet cells and ESSCs from the winter flounder stained positive for sulphated acid mucins, whereas in the yellowtail flounder goblet cells stained positive for sulphated and nonsulphated acid mucin combinations and ESSCs stained only for nonsulphated acid mucins. A pregastric digestive function is proposed, based upon the thick muscularis externa composed of striated circular muscle, the increased surface area due to mucosal folding, the complex histochemistry of the mucus, and the secretory nature of the ESSCs.

Fish mucus layers are the main surface of exchange between fish and the environment, and they possess important biological and ecological functions. Fish mucus research is increasing rapidly, along with the development of high-throughput techniques, which allow the simultaneous study of numerous genes and molecules, enabling a deeper understanding of the fish mucus composition and its functions. Fish mucus plays a major role against fish infections, and research has mostly focused on the study of fish mucus bioactive molecules (e.g., antimicrobial peptides and immune-related molecules) and associated microbiota due to their potential in aquaculture and human medicine. However, external fish mucus surfaces also play important roles in social relationships between conspecifics (fish shoaling, spawning synchronisation, suitable habitat finding, or alarm signals) and in interspecific interactions such as prey-predator relationships, parasite–host interactions, and symbiosis. This article reviews the biological and ecological roles of external (gills and skin) fish mucus, discussing its importance in fish protection against pathogens and in intra and interspecific interactions. We also discuss the advances that “omics” sciences are bringing into the fish mucus research and their importance in studying the fish mucus composition and functions.

Laryngocele represents an abnormal invagination of the mucous membrane from the Morgagni laryngeal ventricle, being filled with air and communicating with the laryngeal inlet. The symptoms are intermittent, with recurrent episodes of dysphonia and airway insufficiency. Exceptionally, the wall of the cyst could become malignant. This case was reported given the association between laryngeal carcinoma and external laryngocele.

A histological study showed the wall of the stomach in Pica pica and Herpestes javanicus consists of four layers: mucosa, submucosa, muscularis externa and serosa. Also, the present study showed many differences in the histological structures of the stomach for each in both types. The stomach of P. pica consists of two portions: the proventiculus and gizzard, while the stomach of H. javanicus consists of three portions: cardiac, fundic and pyloric regions. The mucosa layer formed short gastric folds, named plicae. In the proventiculus of P. pica, sulcus is found between each two plicae, but the folds called gastric pits in the gizzard, which are full with koilin. Lamina properia in both types contained gastric glands (straight simple tubular glands) named superficial glands, as well as another gastric gland found in the submucosa layer of the proventiculus in P. pica only named deep gastric glands. The gastric gland in the stomach of H. javanicus contained: mucous neck cells and parietal cells positive to AB/PAS stains in cardiac portion, as well as chief cells in fundic portion, but pyloric portion had just mucous neck cells. Muscularis externa in both types formed two muscle layers: inner and outer layer.

A histological study showed the wall of the stomach in Pica pica and Herpestes javanicus consists of four layers: mucosa, submucosa, muscularis externa and serosa. Also, the present study showed many differences in the histological structures of the stomach for each in both types. The stomach of P. pica consists of two portions: the proventiculus and gizzard, while the stomach of H. javanicus consists of three portions: cardiac, fundic and pyloric regions. The mucosa layer formed short gastric folds, named plicae. In the proventiculus of P. pica, sulcus is found between each two plicae, but the folds called gastric pits in the gizzard, which are full with koilin. Lamina properia in both types contained gastric glands (straight simple tubular glands) named superficial glands, as well as another gastric gland found in the submucosa layer of the proventiculus in P. pica only named deep gastric glands. The gastric gland in the stomach of H. javanicus contained: mucous neck cells and parietal cells positive to AB/PAS stains in cardiac portion, as well as chief cells in fundic portion, but pyloric portion had just mucous neck cells. Muscularis externa in both types formed two muscle layers: inner and outer layer.

Study targeted to clarification the microscopic features of the esophagus structure in (white breasted kingfisher) bird Halcyon smyrnensis, which is primarily piscivorous, through studying of various histological modifications such as relative development of mucosal folds, mucous-secreting glands and musculature have been shown to be correlated with the specific feeding habits of studying bird. Histological study was conducted on ten adult healthy birds during the period from March to May of 2016 in the Animal House of the College of Science / University of Wasit. The results showed that the esophagus kingfisher birds characterized as a thin flexible muscular tube. The most important characteristic of the installation of the esophagus in a bird Kingfisher histologically that the wall of the esophagus found to be composed of only three layers or tunics: mucous, muscular and adventitious arranged from the inside to outside, referring to the absence of tunica submucosa. Microscopic observation of first mucosal layer of esophageal wall showed that it was consists of lamina propria, epithelia and groups of longitudinal folds without discrimination for presence of muscularis mucosae. Mucosal layer of esophagus wall lined by epithelium of non- keratinized stratified squamous epithelium tissue. Lamina propria noticed to compose of numerous mucous esophageal glands. The histological study of esophageal wall also indicated to the absence of submucosa layer because the difficulty to distinguish from the lamina propria. The second tunica tunica a muscularis externa composed of smooth muscle fibers arranged into two secondary layers, inner circular layer and an outer longitudinal layer. In addition to the mentioned tunics it's found a third layer surrounding the muscularis externa consisted of nerve fibers, and fatty cells known adventitia.

Otorrhoea is a symptom of the presence or leakage of secretions (sulfur, blood, pus, mucus, cerebrospinal fluid or even saliva) from the ear. Otorrhea is an important symptom of ear disease, or may be a manifestation of the spread of diseases in the external auditory canal from the ear. The cause of otorrhoea can be determined in most cases after the history and examination of the patient. The most common causes of purulent otorrhoea are acute otitis externa or acute otitis media. Chronic otitis media with cholesteatoma should be remembered as a lifethreatening condition. Patients with otorrhoea are mostly outpatient and do not require inpatient treatment. Understanding the cause of otorrhoea will help establish the correct diagnosis and prescribe the right effective treatment.

This study investigated the morphological, histological, and histochemical characteristics of the digestive tract of the marbled flounder (Pseudopleuronectes yokohamae). The relative length of the gut of the marbled flounder digestive tract was 1.54 ± 0.10 (n = 20), and it had a simple stomach and 6–9 pyloric caeca. The mucosal folds of the marbled flounder digestive tract exhibited a general branched morphology. The thickness and mucosal fold length of the intestinal muscularis externa showed similar aspects in all areas. The thickness of the intestinal muscularis externa was the thickest in the posterior intestine portion, and the length of mucosal folds was the longest in the anterior intestine portion. It was indicated that food digested by gastric acid in the stomach moves to the anterior portion (including pyloric caeca) and mid portion of the intestine, ensuring effective stimulation of cholecystokinin (CCK)-producing cells. In addition, the distribution pattern of CCK-producing cells in the intestine was very similar to that of mucus-secreting goblet cells. The CCK-producing cells and goblet cells in the marbled flounder were well-adapted to promote optimal control of the digestive process. Based on the morphological and histochemical studies, it was concluded that the marbled flounder displays a digestive tract comparable to that of fish species with carnivorous habits.

SummaryOur aim was to determine the effects of preventing the passage of ingested fluid on the development of the digestive tract in fetal sheep. The esophagus was fistulated and ligated in six fetuses at 90 days of gestation (term = 145 days); vascular catheters were implanted at day 120. Six control fetuses had vascular catheters implanted at day 120. At autopsy (day 135), although fetal body weights were similar in both groups, the abdominal girth and weights of the gastrointestinal tract, liver, and pancreas were reduced in experimental fetuses. In the gastric (abomasal) fundus and antrum, there was evidence of altered mucus composition in epithelial cells, a decrease in thickness of the muscularis externa, and an increase in thickness of the mucosa and its components. In the duodenum, there were significant changes in the thickness of most components of the wall; Brunner's glands were greatly reduced in size or were absent. Glandular cells contained less mucus in comparison to controls. In the proximal small intestine, there were significant reductions in the thickness of most components of the wall, and epithelial cell migration was retarded, resulting in a longer renewal time for villous cells. In the distal small intestine, the diameter of the intestine and submucosal and epithelial cell migration rate were significantly decreased in the experimental group. In summary, the absence of the passage of ingested fluid in fetal sheep restricts the growth and development of the gastrointestinal tract, liver, and pancreas.

AbstractObjectiveExternal dacryocystorhinostomy is thought to cause mucociliary dysfunction by damaging the mucosa, in turn affecting ciliary activity and mucus quality. This study investigated the effect of external dacryocystorhinostomy on sinonasal function.MethodsPatients scheduled for unilateral external dacryocystorhinostomy who underwent endoscopic nasal examination and paranasal sinus computed tomography were included in this study. A saccharine test was performed on the planned surgical side and the mucociliary clearance time was determined. The sinonasal quality of life was measured in all patients, pre-operatively and at six months post-operatively, using the Sino-Nasal Outcome Test-22. The Lund–Kennedy endoscopic score was also determined in all patients, both pre- and post-operatively.ResultsThe study comprised 28 patients (22 females and 6 males). A statistically significant difference was found between the pre- and post-operative saccharine test results (p = 0.006), but not between the pre- and post-operative Sino-Nasal Outcome Test-22 scores (p > 0.05).ConclusionThis study is one of only a few to investigate the effect of external dacryocystorhinostomy on sinonasal function. The results showed that external dacryocystorhinostomy impairs mucociliary clearance. The surgical procedure is well tolerated and does not significantly change nasal symptom scores.

Alors que les poissons téléostéens représentent les deux tiers des vertébrés marins, l'interaction entre leur microbiote externe et leur environnement reste peu étudié, en particulier chez les populations sauvages. Ainsi, le lien entre le microbiote et les ectoparasites n'est pas bien compris. Le microbiote peut agir comme une barrière protectrice contre les pathogènes et/ou être impliqué dans la reconnaissance de l'hôte par les parasites. Les associations hôte-parasite devraient désormais être considérées comme des interactions tripartites où le microbiote façonne le phénotype de l'hôte et sa relation avec les parasites. Ces interactions ont déjà été décrites chez certaines espèces de téléostéens qui peuvent être parasitées par des monogènes (Plathelminthes) qui sont des ectoparasites à cycle de vie direct que l'on trouve couramment sur leur peau et leurs branchies. Leurs larves nagent activement, s'orientent et repèrent leur hôte grâce à des stimuli chimiques. Les communautés bactériennes sont soupçonnées de contribuer à la production de ces signaux et pourraient donc jouer un rôle important dans les mécanismes de spécificité parasitaire.L'objectif de cette thèse était d'explorer les mécanismes qui sous-tendent la spécificité des monogènes pour leur(s) hôte(s) en caractérisant le microbiote, la composition chimique du mucus externe des téléostéens (peau et branchies), et en développant des approches expérimentales pour mieux caractériser le rôle des stades précoces des Lamellodiscus dans cette spécificité. Nous nous sommes concentrés sur l'association entre les Sparidae, une famille de poissons retrouvée en Méditerranée, et les monogènes du genre Lamellodiscus qui présentent des profils de spécificité variés pour leurs hôtes.Au cours de cette thèse, nous avons tout d'abord (i) étudié l'évolution des communautés bactériennes du mucus externe de deux espèces sauvages de sparidés présentant des charges parasitaires en Lamellodiscus contrastées. Nous avons ensuite (ii) caractérisé les communautés bactériennes et la composition chimique du mucus externe de quatre espèces de sparidés sauvages et étudié l'influence de différents facteurs sur leur variabilité (environnementaux ou propres à l'hôte). Nous nous sommes ensuite concentrés sur une espèce qui n'est jamais parasitée par les monogènes du genre Lamellodiscus. Nous avons exploré si cette espèce se distinguait des trois autres par une signature bactérienne et chimique particulière qui pourrait expliquer sa protection vis à vis des Lamellodiscus. Enfin, l'objectif de la dernière partie (iii) était de développer des approches expérimentales pour comprendre quels facteurs sont susceptibles de favoriser l'établissement et le maintien des différents stades de vie du parasite sur son hôte. Un système non-invasif de collecte d'œufs de Lamellodiscus a d'abord été développé. À partir de là, nous avons pu établir des conditions optimales de maintien in vitro d'œuf de Lamellodiscus pour favoriser leur éclosion. Nous avons, alors, réalisé une première caractérisation morphologique des stades de vie précoces d'une espèce de Lamellodiscus à l'aide de microscopie optique et électronique à balayage. En parallèle, nous avons développé une méthode pour, à terme, étudier le comportement et la préférence larvaire pour des mucus de différentes espèces de sparidés
While teleost fishes represent two-third of all marine vertebrates, the interaction between their external microbiota and their environment remains poorly studied, especially for wild populations. Hence, the role of their microbiota in relationship with ectoparasites is largely unknown. Microbiota can act as a protective barrier against pathogens, and/or be involved in host recognition by parasites, and host-parasite associations should be considered as a tripartite interplay where the microbiota shapes the host phenotype and its relation to parasites. These interactions have already been described in some teleost species that can be parasitized by Monogeneans (Platyhelminthes) which are direct life cycle ectoparasites commonly found on their skin and gills. Their larvae actively swim towards their host based on chemical stimuli. Bacterial communities are suspected to contribute to these cues and could play a significant role in host-parasite specificity mechanisms.The objective of this thesis was to explore the mechanisms involved in the specificity of monogenean for their host(s) through the characterization of wild teleost external mucus (skin and gills) microbiota and metabolite production and the development of experimental approaches to better characterize the role of early life stages of Lamellodiscus in host specificity. We used as biological model a well-known association formed by Sparidae, a fish family found in Mediterranean Sea, and Lamellodiscus monogeneans, a species-rich genus that exhibits various patterns of host specificity.During this thesis, we first (i) studied the evolution of bacterial communities in the external mucus of two wild sparid species with contrasting Lamellodiscus monogeneans parasitic loads. We have then (ii) characterized the bacterial communities and chemical composition of the external mucus of four wild sparid species and studied the influence of different environmental or host-specific factors on their variability. One of these species, never parasitized by the Lamellodiscus monogeneans, was especially studied to determine whether it has a distinct bacterial and chemical signature that could explain its protection against Lamellodiscus. The objective of the last part (iii) was to develop experimental approaches to investigate the factors that promote the establishment and maintenance of different life stages of monogeneans on their host. A non-invasive system was developed for collecting Lamellodiscus eggs in aquariums. From there, we cultured larvae in vitro by establishing optimal conditions to maintain Lamellodiscus eggs and induce their hatching. We conducted an initial morphological characterization of the early stages of a Lamellodiscus species using light and scanning electron microscopy. We have, in parallel, developed a method to ultimately study in vitro oncomiracidia behavior and preference for mucus from different sparid species

Masters of Science
There is a need for defined models of human nutritional disorders partly because serious misconceptions about models are common amongst researchers. Historically a large variety of species has been used including primates, pigs, rats, lagomorphs. Advantages various small carnivores and and disadvantages are not well known and availability is a major factor. In 1753 John Hunter used pigs to study bone growth in one of the first scientifically controlled nutrition experiments (Kobler 1960). Rats were most likely the first animals to be bred specifically for scientific purposes and there is evidence that they were used in nutrition experiments during the late eighteenth century (Kobler 1960). Experience with carcinogenesis in animals has shown the great diversity of results which may possibly be obtained from different species (Lave et al. 1988). This is pertinent to nutritional research as there is an established link between diet and cancer. The selection of a suitable substitute to attempt to model possible human response to a variety of procedures is dependent upon criteria among which the following are possibly the more important. Availability; this is of great importance in Southern Africa where the cost of importation of exotic species. must be taken into account. Du Plessis (1981) referred to the fact that our indigenous primates were a valuable resource. A second consideration must be the cost the selected animal in a scientifically acceptable environment. Keeping animals of maintaining and ethically for research purposes in an uncontrolled environment could well lead to erroneous conclusions being made. Thirdly the cost of a research program in which animals are used may be increased if there is insufficient knowledge of the model selected. A paucity of knowledge available about an animal may affect the viability of an experiment. The need for precise information regarding the effects of extended term dietary supplementation of experimental animals has been noted by Fincham et. al. (1987) . Additionally the selected animal should preferably have similar dietary requirements to man, and have a life span which will enable extended term investigations.

Urticaria is an inflammatory complaint characterized by short-lived skin swellings termed ‘wheals’ or ‘hives’. It can be divided into acute urticaria, where the disease has an abrupt onset, and chronic urticaria, where wheals have occurred on a regular basis for over 6 weeks. Physical urticaria is a subgroup of chronic urticaria where an underlying external/physical trigger can be identified, while contact urticaria arises from contact with a chemical substance on the skin or mucous membranes. Angiooedema represents a similar process affecting the deeper dermal tissue and has a predilection for the skin around the eyes and mouth. It may occur in association with urticaria or as an isolated complaint.

Abstract Normally, for conception to occur in vivo spermatozoa must be deposited at the site of insemination around the external cervical os at a time when the cervical mucus is receptive to penetration by spermatozoa. This initial process of sperm-cervical mucus interaction is an essential first step in the complex series of events that take place in the relatively inaccessible female tract resulting in the production of a zygote which, hopefully, will implant and develop into a new individual. Consequently, its assessment is an integral part of the diagnostic workup of an infertile couple, and the various techniques available are described in this chapter.

The nasal cavity is the entrance to the respiratory tract. Its functions are to clean, warm, and humidify air as it is inhaled. Respiratory mucosa covered by pseudostratified ciliated epithelium and goblet cells, as described in Chapter 5 and illustrated in Figure 5.2B, lines the majority of the nasal cavity. The cilia and mucus trap particles, thus cleaning the air; the mucus also humidifies the air and warming is achieved through heat exchange from blood in the very vascular mucosa. The efficiency of all these processes is increased by expanding the surface of the nasal cavity by folds of bone. The nasal cavity also houses the olfactory mucosa for the special sense of olfaction although the olfactory mucosa occupies a very small proportion of the surface of the nasal cavity. The nasal cavity extends from the nostrils on the lower aspect of the external nose to the two posterior nasal apertures between the medial pterygoid plates where it is in continuation with the nasopharynx. Bear in mind that in dried or model skulls, the nasal cavity is smaller from front to back and the anterior nasal apertures seem extremely large because the cartilaginous skeleton of the external nose is lost during preparation of dried skulls. As you can see in Figure 27.1 , the nasal cavity extends vertically from the cribriform plate of the ethmoid at about the level of the orbital roof above to the palate, separating it from the oral cavity below. Figure 27.1 also shows that the nasal cavity is relatively narrow from side to side, especially in its upper part between the two orbits and widens where it sits between the right and left sides of the upper jaw below the orbits. The nasal cavity is completely divided into right and left compartments by the nasal septum . From the anterior view seen in Figure 27.1 , you can see that the surface area of lateral walls of the nasal cavity are extended by the three folds of bone, the nasal conchae. The skeleton of the external nose shown in Figure 27.2 comprises the nasal bones, the upper and lower nasal cartilages, the septal cartilage, and the cartilaginous part of the nasal septum.

The delicate yet definitive deflections of the pinna (wing/fin) of the external ear contribute to the collection of sound. The external acoustic meatus is responsible for the transmission of sounds to the tympanic membrane, which in turn separates the external ear from the middle ear. The middle ear is an air filled (from the nasopharynx via the eustachian tube), mucous membrane lined space in the petrous temporal bone. It is separated from the inner ear by the medial wall of the tympanic cavity – bridged by the trio of ossicles. The inner ear refers to the bony and membranous labyrinth and their respective contents. The osseus labyrinth lies within the petrous temporal bone. It consists of the cochlea anteriorly, semicircular canals posterosuperiorly and intervening vestibule – the entrance hall to the inner ear whose lateral wall bears the oval window occupied by the stapes footplate.

The external nose is pyramidal and consists of a bony cartilaginous framework. The root/radix is continuous with the forehead an inferiorly terminates at the nasal tip. The dorsum of the nose is formed by two lateral surfaces that converge in the midline. The cartilaginous structure of the nose is formed by paired upper (lateral) cartilages that contribute to the internal nasal valve with the nasal bones, and lower lateral cartilages, combined with additional minor nasal cartilages that surround the ala. The nasal septum relies upon anastomoses from five vessels: two from the ophthalmic, two from the maxillary and one from the facial. Collectively, they form Kieselbach’s plexus. The paranasal sinuses are the frontal, sphenoidal, ethmoidal and maxillary – located within the bones of the same name. They are paired structures lined with mucosa that is continuous with the lateral nasal side wall into which they drain, facilitating clearance of mucus by way of the mucociliary escalator.

Abstract Most recently, the physiology of the salivary glands has especially foregrounded, within their functioning, certain phenomena which are usually called psychic. The latest research on the salivary glands by Glinski?, Vul’fson, Henri and Malloizel, and Borisov has revealed a most perfect adaptability of these glands to external stimulations, as had already been anticipated by Claude Bernard. In response to food that gets into the mouth and is hard and dry, the salivary glands release great quantities of saliva, and mixing with it allows such food to realize its chemical properties and helps its mechanical processing, thus aiding its passage through the esophagus into the stomach. In contrast, saliva is produced in much smaller quantities when the food contains a lot of free water, and less saliva is produced the higher the water content. To be sure, milk causes a decent amount of saliva to flow, but it should be kept in mind that the addition of mucous saliva to milk prevents, by virtue of the mucous layering, the formation in the stomach of a large compact curd mass, and by this it facilitates the digestive effect of gastric juice on the milk. In response to water or to a physiological saline solution, no salivation occurs at all, as saliva is of no use to them. When strong chemical irritants are introduced into the mouth, saliva always flows in quantities strictly proportional to the irritating strength of these substances.

Abstract In intertidal mud and sand, diatoms are the dominant microalgae, with about 10 cells cm-2 andanannual net production of roughly 100 g C m-2. One-third may be consumed by the zoobenthos. Large deposit feeders ingest microalgae together with sediment particles. Smaller ones scrape algal cells from sand grains or capture mobile diatoms. These are either ingested intact or are punctured and sucked out. Bulk measurements on primary production and on consumption provide little insight into plant-animal interactions in shallow sediments. Analyses should differentiate between type of algae and mode of feeding. Large epipelic diatoms are occasionally subject to overgrazing, while the small epipsammic diatoms are utilized to a lesser extent. At moderate density some grazers stimulate algal growth. Gardening is achieved by excretion of ammonia and secretion of mucus. The extracellular mucopolysaccharides produced by diatoms increase the surface stability of sediments and enhance the accretion of organic deposits. This is beneficial to deposit feeders. Heavy grazing on mud-flats reduces diatom density, and the habitat may become more sandy because of interference with the accretion of mud. In sand, bioturbating macrofauna depresses microalgal growth by frequent burial. Large burrowers occasionally anchor strings of green macroalgae, which subsequently grow into coherent algal mats, changing the entire habitat profoundly.

There are three paired major salivary glands of the head and neck, all named according to their location and each contributing to saliva and enzyme production via their respective ducts to assist with mastication and digestion. At rest, the lion’s share (60%) of saliva production is from the submandibular glands. On stimulation, the parotid contribution increases from 20% to 50%. There are up to 1000 minor salivary glands found within the submucosa of the oral cavity – 1-2mm in size and predominantly mucous in nature. The parotid glands are irregular shaped masses of lobulated tissue situated on the side of the face, reaching from the zygomatic arch superiorly to the upper part of the neck inferiorly where they overly the posterior belly of digastric and upper sternocleidomastoid muscle. Anteriorly, the gland lies between the posterior border of the mandibular ramus before continuing below the external acoustic meatus towards the mastoid process posteriorly.

Abstract Lohmann (1898, 1899, 1909a, 1933) was the first investigator to recognize the true function of the appendicularian house, which is to concentrate and collect particulate matter from the sea for feeding. He examined the gut contents of Oikopleura albicans and in this way identified an entirely new size class of plankton in the sea, which he called ‘nanoplankton’ (Lohmann, 1909a). The structure of the house is described in detail in Chapter 6; it is remarkably complex and its operation is only well understood in detail in a few oikopleurid species, and less well in a single fritillariid. Essentially, there are in oikopleurids usually three filters involved in food collection; their structure determining the size class of particles a given species can feed upon. The inhalent flow produced by oscillation of the tail draws water into the house via an external relatively coarse filter, then a food collecting filter or trap concentrates particulate material, which is drawn along a short tube to the mouth by the action of spiracular cilia. After entering the pharynx, the particles are trapped on a mucous filter and they enter the oesophagus.

Ulcerative colitis is a chronic relapsing and remitting disease in which chronic inflammation affects the rectum and extends proximally to a variable extent. The precise aetiology remains unknown but involves an interplay between reduced diversity in the gut microbiota and a genetically dysregulated gut immune system and epithelial barrier. Typical presentation of mild or moderate disease is with a gradual onset of symptoms including diarrhoea, rectal bleeding, and the passage of mucus. Severe disease is characterized by anorexia, nausea, weight loss, and severe diarrhoea, with the patient likely to look unwell with fever, tachycardia, and other signs of volume depletion, and the abdomen may be distended and tympanitic, with reduced bowel sounds and marked colonic tenderness. Diagnosis is usually made on the basis of exclusion of infective colitis by stool culture and the finding of typical diffuse inflammation in the rectum and above at sigmoidoscopy. Management requires rapid control of symptoms with induction therapy followed by maintenance of remission. Mild disease is typically treated with 5-aminosalicyclic acid delivered both orally and by enema, and moderate disease by 5-aminosalicyclic acid and steroids. Patients with severe disease require hospital admission, intravenous steroids, and daily review by both a physician and a surgeon experienced in the management of ulcerative colitis. Ciclosporin or infliximab are used as rescue therapies for steroid-resistant acute severe ulcerative colitis, but colectomy should not be delayed when this is required. Maintenance therapy with immunomodulators and biological therapies are both effective at maintaining remission, and several new biologicals are in clinical trials.

Approximately 80% of the pathogens that lead to deadly infections in humans choose mucosal tissue as the first site of infection. The mucosal surfaces of the body include the gastrointestinal tract, airways, oral cavity, and urogenital mucosa, which provide a large area conducive to the invasion and accumulation of many microorganisms and are of great importance in this regard. The large extent of mucus, as well as the accumulation of bacteria and countless foreign antigens in these areas, are the most important reasons for the importance of mucosal tissues. In addition to the myriad of symbiotic bacteria, large amounts of oral antigens (both pathogenic and non-pathogenic) enter a person’s body daily and human mucosal tissues are exposed to these antigens. The function of the mucosal immune system is to distinguish pathogenic antigens from non-pathogenic ones. In this way, against a large number of oral antigens or co-tolerant microorganisms, and pathogenic antigens, a favorable (and even non-inflammatory, possible) immune response is produced. Mucosal tissue, as the largest lymphatic organ in the body, is home to 75% of the lymphocyte population and produces the highest amount of immunoglobulin. The amount of secreted IgA (slgA) produced daily by mucosal surfaces is much higher than the IgG produced in the bloodstream. A 70 kg person produces more than 3 grams of IgA per day, which is about 70–60% of the total antibodies produced in the body. The first embryonic organ in which immune system cells are located in the intestine. Some researchers consider this organ (and specifically mucosal lymph nodes) to be the source of the human immune system.

Flagella and cilia are examples of actively oscillating, whiplike biological filaments that are crucial to processes as diverse as locomotion, mucus clearance, embryogenesis and cell motility. Elastic driven rod-like filaments subjected to compressive follower forces provide a way to mimic oscillatory beating in synthetic settings. In the continuum limit, this spatiotemporal response is an emergent phenomenon resulting from the interplay between the structural elastic instability of the slender rods subjected to the non-conservative follower forces, geometric constraints that control the onset of this instability, and viscous dissipation due to fluid drag by ambient media. In this paper, we use an elastic rod model to characterize beating frequencies, the critical follower forces and the non-linear rod shapes, for pre-stressed, clamped rods subject to two types of fluid drag forces, namely, linear Stokes drag and non-linear Morrison drag. We find that the critical follower force depends strongly on the initial slack and weakly on the nature of the drag force. The emergent frequencies however, depend strongly on both the extent of pre-stress as well as the nature of the fluid drag.

Colorectal cancer (CRC) is nowadays one of the deadliest cancer but the high surviving rate is achievable if the disease is diagnosticated and treated at the early stage. However, the standard procedure represents a discomfortable treatment for many patients at the point that many are discouraged in undergoing routine screening program. In fact, the clinician has to insert and guide by hand a semi-flexible tubular colonoscope and might apply significant forces and torques on the colon walls, with the complications of creating loops in the intestine, tissue damage or even perforation. For this reason, research in capsule robotic colonoscopy is in high demand [1]; the main objective of robotics in this field is to design a system capable of navigating inside the large intestine in order to provide visual inspection of the lumen, possibly, carrying surgical tools required in the colonoscopy procedure, i.e. polypectomy, without the creation of large pushing forces and loops. Human colon is about 130 cm long and composed by 4 consecutive tracts, joint at different angles, named sigmoid, descending, transverse and ascending colon. The diameter the tubular organ can changes from 25 mm to 70 mm, reaching up to 80 mm if insufflated with CO2 gas, often adopted in colonoscopy. Nonetheless, colon wall is a multilayers membrane that consists of four main layers (mucosa, submucosa, muscularis externa and serosa) which makes the membrane very compliant to large deformation and very slippery, being the internal wall of the colon characterized by continuous secretion of mucus Due to both the morphology and the frictional behaviour of the colon, the design of robots that are able to crawl the intestine and perform the screening of the organ is a challenge. Various locomotion strategies for micro robotic devices have been explored, such active capsules inspired by bio-mimetic locomotion strategies, such insect or caterpillar, or by use of locomoting members to self- propel once inside the colon such wheels or tracks [2]. Nonetheless, current robotic solutions are still far away to replace the standard colonoscopy due to the challenges in integrating reliable locomotion strategy in small size robots able to face the complex environment represented by the colon. In this work, we discuss the design and the features of the SOFTScreen system [3], discussing the testing of its locomotion capability inside a silicone phantom resembling the colon surface.