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Peristalsis enables transport of the food bolus in the gut. Here, I show by dynamicex vivointra-cellular calcium imaging on living embryonic gut explants that the most primitive form of peristalsis that occurs in the embryo is the result of inter-cellular, gap-junction-dependent calcium waves that propagate in the circular smooth muscle layer. I show that the embryonic gut is an intrinsically mechanosensitive organ, as the slightest externally applied mechanical stimulus triggers contractile waves. This dynamic response is an embryonic precursor of the ‘law of the intestine’ (peristaltic reflex). I show how characteristic features of early peristalsis such as counter-propagating wave annihilation, mechanosensitivity and nucleation after wounding all result from known properties of calcium waves. I finally demonstrate that inter-cellular mechanical tension does not play a role in the propagation mechanism of gut contractile waves, unlike what has been recently shown for the embryonic heartbeat. Calcium waves are a ubiquitous dynamic signalling mechanism in biology: here I show that they are the foundation of digestive movements in the developing embryo.This article is part of the Theo Murphy meeting issue on ‘Mechanics of development’.

An analysis of gut formation in the fruit fly has revealed how gene expression and mechanical forces are coordinated in adjacent populations of cells. The findings highlight the tissue-level control of embryonic development. Tissue-level control of development is revealed by endoderm analysis.

It is widely held that the bilaterian tubular gut with mouth and anus evolved from a simple gut with one major gastric opening. However, there is no consensus on how this happened. Did the single gastric opening evolve into a mouth, with the anus forming elsewhere in the body (protostomy), or did it evolve into an anus, with the mouth forming elsewhere (deuterostomy), or did it evolve into both mouth and anus (amphistomy)? These questions are addressed by the comparison of developmental fates of the blastopore, the opening of the embryonic gut, in diverse animals that live today. Here we review comparative data on the identity and fate of blastoporal tissue, investigate how the formation of the through-gut relates to the major body axes, and discuss to what extent evolutionary scenarios are consistent with these data. Available evidence indicates that stem bilaterians had a slit-like gastric opening that was partially closed in subsequent evolution, leaving open the anus and most likely also the mouth, which would favour amphistomy. We discuss remaining difficulties, and outline directions for future research.

This work addresses fundamental issues in the mathematical modelling of the diffusive motion of particles in biological and physiological settings. New mathematical results are proved and implemented in computer models for the colonisation of the embryonic gut by neural cells and the propagation of electrical waves in the heart, offering new insights into the relationships between structure and function. In particular, the thesis focuses on the use of non-local differential operators of non-integer order to capture the main features of diffusion processes occurring in complex spatial structures characterised by high levels of heterogeneity.

Highlights • Intestinal malrotation is a congenital rotational anomaly that occurs as a result of an arrest of normal rotation of the embryonic gut, said to occur in 1 in 6000 live births. Once thought to be a disease of infancy, is now more prevalent in older ages. • Cases of left sided appendicitis with previously undiagnosed intestinal malrotation therefore becomes more challenging to diagnose, and often time’s definitive surgical management is delayed. A varied list of differential diagnosis needs to be considered. • This case presentation shows the difficulties encountered and the variation in presentation that lead us down a different path prior to attaining a formal diagnosis. • CT abdomen was required to confirm the diagnosis, and in a paediatric age group, radiation exposure is always weighed upon risk-benefit ratio. • Definitive management is surgical intervention., Introduction Intestinal malrotation is a congenital rotational anomaly that occurs as a result of an arrest of normal rotation of the embryonic gut, said to occur in 1 in 6000 live births. Due to the abnormal caecal and appendix position, diagnosis of acute appendicitis becomes more challenging, thus leading to diagnostic and operative intervention delays. Our aim is to highlight the diagnostic challenges in this clinical scenario. Presentation of case We present a case of a 10 year old boy with previously undiagnosed intestinal malrotation with a left sided acute appendicitis. Initial symptoms lead to a treatment for gastroenteritis, however, due to ongoing pain a CT abdomen was done which showed the malrotation and appendicitis. He required a laparoscopy converted to open appendicectomy due to an appendicecal mass. Discussion Historically, intestinal malrotation was thought to be a disease of infancy with infrequent occurrence after the age of one year. However, recent analysis has shown an increase in presentations after one year of life into adulthood. Thus, the prevalence of malrotation in children and adults over the age of one year appear to be higher than initially presumed. Conclusion Left sided acute appendicitis is a diagnostic dilemma, thus often leading to management delays. It is pertinent to remember that malrotation of the gut is more common than previously thought, and not just a disease of infancy. It is advisable to consider imaging studies while balancing the risk-benefit-ratio of radiation exposure, especially in paediatric cases to cinch the diagnosis.

Sasang Constitutional Medicine (SCM) offers a medical principle that classifies humans into four constitution groups and guides their treatment with constitution-matched medical assistance. The principle of this traditional medicine, although requires significant scientific support, appears to suggest a genetic influence on constitution type. The relative frequency of constitution types in a population, for instance, has remained relatively constant since Jema Lee first described them from his observations. In addition, the body compartment concept of SCM appears to be related to the anterio–posterior patterning of the embryonic gut and associated internal organs. This study describes the attributes of the constitution concept of SCM that can be interpreted in the language of genetics and current approaches to identity the genetic factors that make up the constitution. These efforts should make it possible to interpret the principle of this traditional medicine scientifically. Considering the recent trend in medicine that pursues individualized or tailored medical offerings, once SCM is proven to be explainable with scientific evidence, it will be able to contribute to and take a place in the rapidly evolving medicine environment.

Carcinoid tumors are neuroendocrine tumors and most frequently occur within tissues derived from the embryonic gut. These tumors can occur in any organ but are very rare in the paratesticular region. We hereby report a case of paratesticular carcinoid in a 70-year-old male who, to the best of our knowledge, is the oldest patient reported so far in the world literature.

The epithelial-to-mesenchymal transition (EMT), a key process in morphogenesis, is often driven by repressing expression of adherens junction components, such as E-cadherin. In this issue of Developmental Cell, Campbell et al. (2011) uncover an alternative mechanism in the Drosophila embryonic gut that promotes EMT via Serpent, a GATA transcriptional repressor of the apicobasal polarity gene crumbs.

Four to 48 hours after iv and sc administration of teratogenic doses of trypan blue to rats and mice the uterus was removed and rapidly frozen, after having been placed in a horizontal plane, and frozen sections were attached to tape and dried at a low temperature. By this procedure embryos and placental structures were present in the same sections and loss or redistribution of the dye was minimized. The dye was found in the yolk-sac cavity and to be accumulated in the visceral (proximal) endoderm. It was also acculmulated in the embryonic endoderm--forming the embryonic gut. This accumulation occurred after the administration of the trypan blue up to the time of closure of the vitelline duct, which occurs at 11 days postconception in rats and 9.5 days in mice. None was found when injection was made after this closure. No dye was detected in the ecto- and mesodermal layers. The period of embryonic uptake of trypan blue largely corresponds with the period of teratogenic sensitivity in these species as reported by others.

Most animals exhibit stable left-right asymmetries in their body. Although significant progress has been made in elucidating the mechanisms that set up these asymmetries in vertebrates, nothing is known about them in Drosophila. This is usually attributed to the fact that no reversals of stable left-right asymmetries have been observed in Drosophila, although relevant surveys have been carried out. We have focused on the asymmetry of the proventriculus in the embryonic gut of Drosophila, an aspect of left-right asymmetry that is extremely stable in wild-type flies. We show that this asymmetry can be reversed by mutations in the dicephalic and wunen genes, which also cause reversals in the antero-posterior axis of the embryo relative to its mother. This is the first observation to suggest that left-right asymmetries in Drosophila can be reversed by genetic/developmental manipulations. It also suggests that maternal signals may initiate the specification of some left-right asymmetries in the embryo.