The Vascularization of the Digestive Tract Studied by Scanning Electron Microscopy with Special Emphasis on the Teeth, Esophagus, Stomach, Small and Large Intestine, Pancreas, and Liver

The periodontal vessels in adult rats show a ladder-like pattern; in guinea pigs molars, by contrast, they present a honey-comb pattern. The vascular architecture in human teeth seems to be similar to that of rabbits. In guinea pigs, rats, rabbits and humans esophagus circumferential vessels give off perforating vessels. In human esophagus the number and diameter of the vessels in the submucous venous plexus decrease from proximal to distal. In the stomach the subepithelial capillary network shows a honey-comb pattern reflecting the arrangement of the gastric pits. A local portal system between the gastric glands and the surface mucosal cells for the transport of HCO3- ions has been suggested. In the small intestine of humans and rabbits the existence of a dual blood supply of the villus has meanwhile been established. It consists of pericryptal capillaries for the lower portion of the villus (tuft pattern) and a direct arterial supply up to the villus tip (fountain pattern). The colonic microvasculature closely resembles that of the stomach. In the pancreas the insulo-acinar portal system is physiologically significant in that it connects the venules draining the islets with the acini. Venous sphincters in the vascular system of the exocrine pancreas of the rat are of particular functional importance. The hepatic sinusoids are supplied both by the hepatic artery and the branches of the portal vein. The peribiliary plexus is supplied by the afferent vessels of the hepatic artery, the efferent vessels drain the plexus either into the sinusoids or into the lobular vein

Esophageal Vasculature in the Guinea Pig: A Scanning Electron Microscope Study of Vascular Corrosion Casts

The esophageal vascularization of adult male and female albinotic Guinea pigs (Cavia porcellus) is studied by means of light microscopically evaluated serial sections and by scanning electron microscopy (SEM) of vascular corrosion casts. Bronchoesophageal artery (cervical portion), direct branches of tha aorta, recurrent branches of the intercostal arteries (thoracic portion) as well as of the left gastric artery (abdominal portion) supply the esophagus; internal jugular vein, inferior thyroid vein (cervical portion), azygos vein, intercostal veins (thoracic portion) and portal vein, gastroepiploic vein and cranial pancreatoduodenal vein (abdominal portion) drain it. Longitudinally arranged arterioles, venules and capillaries lying at the level of the lamina propria of the esophageal mucosa around the whole circumference of the organ are the most striking vascular features, whereby the venules are considered as those vessels from which esophageal varices arise under pathological conditions

Sphincters in the Rat Pulmonary Veins. Comparison of Scanning Electron and Transmission Electron Microscopic Studies

The microvasculature of the rat lung was studied by scanning electron microscopy (SEM) and transmission electron microscopy (TEM) of vascular corrosion casts and tissue sections. Particular emphasis was placed on postcapillary venules, pulmonary venules and small pulmonary veins (small interlobular veins). Casts of lung capillaries appeared inconspicuous with smooth surface. On the casts of pulmonary venules and small pulmonary veins, by contrast, series of narrow annular constrictions, present at regular distances of 20-25 μm, were seen. These constrictions may be drastic, narrowing down the caliber of the vessel up to 50%. In the constrictions the marks of circularly running tubular structures were seen and were interpreted as being caused by circular bands of smooth muscle cells. Tissue sections of the corresponding vascular wall showed the presence of single or grouped smooth muscle cells which regularly formed myoendothelial junctions. These smooth muscle cells are interpreted as sphincters, responsible for the constrictions seen on cast preparations. Axon terminals were not found in spatial relationship to these sphincters. It is suggested that the described venous sphincters are governed by blood-borne and/or endothelium-derived substances and may significantly influence the blood flow

Dynamic changes in the epigenomic landscape regulate human organogenesis and link to developmental disorders

How the genome activates or silences transcriptional programmes governs organ formation. Little is known in human embryos undermining our ability to benchmark the fidelity of stem cell differentiation or cell programming, or interpret the pathogenicity of noncoding variation. Here, we study histone modifications across thirteen tissues during human organogenesis. We integrate the data with transcription to build an overview of how the human genome differentially regulates alternative organ fates including by repression. Promoters from nearly 20,000 genes partition into discrete states. Key developmental gene sets are actively repressed outside of the appropriate organ without obvious bivalency. Candidate enhancers, functional in zebrafish, allow imputation of tissue-specific and shared patterns of transcription factor binding. Overlaying more than 700 noncoding mutations from patients with developmental disorders allows correlation to unanticipated target genes. Taken together, the data provide a comprehensive genomic framework for investigating normal and abnormal human development

An evaluation for the standardization of the Allium cepa test as cytotoxicity and genotoxicity assay

A general report on the use of the Allium test as cytotoxicological and genotoxicological assay is proposed, with particular emphasis about the standardization of the test in several common applications. The intraspecific variation in Allium cepa has been overlooked, as in most investigations no mention is made about origin and denomination of the onion cultivar used. A standardization of the used material would allow a better generalization of the results, since we cannot be sure that all cultivars would give the same response. A more frequent use of transmission electron microscopy (TEM) investigation is proposed. Even if relatively time consuming and not available in all laboratories, it may help to better understand the mechanism of cytotoxicity, since many morphological characters may appear similar but be arisen from different processes observable only with TEM. About statistical testing, tests other than chi-squared may be used in case of a lower amount of data. The most commonly used statistical tests are the parametric tests ANOVA and Student’s t, and the nonparametric tests Kruskal–Wallis and Mann–Whitney U, for analysis of variance. Tests should be used also to assess the minimal sample dimension for obtaining significance, since data collection (microscope observation) appears to be one of the main bottle necks of the test. Also the use of the Allium test for testing liposomes and other nanovectors for drug delivery is proposed, in order to assess the cytotoxicity of these types of medium and the possible increase in cytotoxicity of the associated drug

Developmental dynamics of sea urchin and sea star cis-regulation and the evolution of echinoderm genome organization

Trabajo presentado en EMBO Workshop The evolution of animal genomes, celebrado en modalidad virtual del 13 al 17 de septiembre de 2021

Genomic adaptations to aquatic and aerial life in mayflies and the origin of insect wings

The evolution of winged insects revolutionized terrestrial ecosystems and led to the largest animal radiation on Earth. However, we still have an incomplete picture of the genomic changes that underlay this diversification. Mayflies, as one of the sister groups of all other winged insects, are key to understanding this radiation. Here, we describe the genome of the mayfly Cloeon dipterum and its gene expression throughout its aquatic and aerial life cycle and specific organs. We discover an expansion of odorant-binding-protein genes, some expressed specifically in breathing gills of aquatic nymphs, suggesting a novel sensory role for this organ. In contrast, flying adults use an enlarged opsin set in a sexually dimorphic manner, with some expressed only in males. Finally, we identify a set of wing-associated genes deeply conserved in the pterygote insects and find transcriptomic similarities between gills and wings, suggesting a common genetic program. Globally, this comprehensive genomic and transcriptomic study uncovers the genetic basis of key evolutionary adaptations in mayflies and winged insects

Objective comparison of methods to decode anomalous diffusion

Deviations from Brownian motion leading to anomalous diffusion are found in transport dynamics from quantum physics to life sciences. The characterization of anomalous diffusion from the measurement of an individual trajectory is a challenging task, which traditionally relies on calculating the trajectory mean squared displacement. However, this approach breaks down for cases of practical interest, e.g., short or noisy trajectories, heterogeneous behaviour, or non-ergodic processes. Recently, several new approaches have been proposed, mostly building on the ongoing machine-learning revolution. To perform an objective comparison of methods, we gathered the community and organized an open competition, the Anomalous Diffusion challenge (AnDi). Participating teams applied their algorithms to a commonly-defined dataset including diverse conditions. Although no single method performed best across all scenarios, machine-learning-based approaches achieved superior performance for all tasks. The discussion of the challenge results provides practical advice for users and a benchmark for developers. Deviations from Brownian motion leading to anomalous diffusion are ubiquitously found in transport dynamics but often difficult to characterize. Here the authors compare approaches for single trajectory analysis through an open competition, showing that machine learning methods outperform classical approaches

Hip joint articular soft tissues of non-dinosaurian Dinosauromorpha and early Dinosauria: evolutionary and biomechanical implications for Saurischia

Dinosauromorphs evolved a wide diversity of hind limb skeletal morphologies, suggesting highly divergent articular soft tissue anatomies. However, poor preservation of articular soft tissues in fossils has hampered any follow-on functional inferences. We reconstruct the hip joint soft tissue anatomy of non-dinosaurian dinosauromorphs and early dinosaurs using osteological correlates derived from extant sauropsids and infer trends in character transitions along the theropod and sauropodomorph lineagues. Femora and pelves of 107 dinosauromorphs and outgroup taxa were digitized using 3D imaging techniques. Key transitions were estimated using maximum likelihood ancestral state reconstruction. The hips of dinosauromorphs possessed wide a disparity of soft tissue morphologies beyond the types and combinations exhibited by extant archosaurs. Early evolution of the dinosauriform hip joint was characterized by the retention of a prominent femoral hyaline cartilage cone in post-neonatal individuals, with the cartilage cone independently reduced within theropods and sauropodomorphs. The femur of Dinosauriformes possessed a fibrocartilage sleeve on the metaphysis, which surrounded a hyaline core. The acetabulum of Dinosauriformes possessed distinct labrum and antitrochanter structures. In sauropodomorphs, hip congruence was maintained by thick hyaline cartilage on the femoral head, whereas theropods relied on acetabular tissues such as ligaments and articular pads. In particular, the craniolaterally ossified hip capsule of non- Avetheropoda neotheropods permitted mostly parasagittal femoral movements. These data indicate that the dinosauromorph hip underwent mosaic evolution within the saurischian lineage and that sauropodomorphs and theropods underwent both convergence and divergence in articular soft tissues, correlated with transitions in body size, locomotor posture, and joint loading