The role, carrier and mission of neural crest cells in the skin

The neuro crest arising from the ectoderm is a transient structure and disappears as the neurocrest cells leave these places to invade the whole embryo. The epidermis develops from the ectoderm in the fourth embryonal weeks. The embryos consist of cranial-,vagal-, truncal and sacral segments and the neuro crest cells migrate from these places to form various structures, including the peripheral nerve system, the craniofacial bones and cartilages, etc. The neuro crest cells degrade the basal membrane of neural tube and thereafter migrate through the extracellular matrix in ventromedial and dorsolateral direction. Neural crest cells use various cell adhesion molecules and diferent proteaes. The invasive capacity of these cells is infuenced by aquaporin-1 , too. . The sensory nerves developig from the neuro- crest cells can be found in the epidermis and its appendicular organ, the dermal autonomic nerves in the dermis. The epidermal melanocytes develop partly from the neural crest cells, partly from the Schwann cells of the sensory nerves. The cutaneous nerves produce and secrete neuropeptides thus contributing to the development of the skin into a neuroimmuno-endocrin organ.

Ecology

Host ecological characteristics, such as body size, longevity, or social living, affect parasitism. Host populations can be regulated in size by their parasites; they can even drive host populations to extinction, usually after hosts have been weakened by other factors. Parasites, therefore, threaten endangered populations and species. Parasites also affect host ecological communities and food webs via effects on competitive ability or with apparent competition. In diverse host communities, infectious diseases become ‘diluted’. Parasite ecological communities seem to have a variable and transient structure; no universal explanation for the observed patterns exists. Host migration can transfer parasites to new areas or leave parasites behind. Disease emergence from an animal reservoir (zoonoses) is especially important. Many human diseases have such an origin, and these have repeatedly caused major epidemics. Climate change will also affect parasitism; however, the direction of change is rather complex and depends on the particular systems.

Sox2 Controls Periderm and Rugae Development to Inhibit Oral Adhesions

In humans, ankyloglossia and cleft palate are common congenital craniofacial anomalies, and these are regulated by a complex gene regulatory network. Understanding the genetic underpinnings of ankyloglossia and cleft palate will be an important step toward rational treatment of these complex anomalies. We inactivated the Sry (sex-determining region Y)–box 2 ( Sox2) gene in the developing oral epithelium, including the periderm, a transient structure that prevents abnormal oral adhesions during development. This resulted in ankyloglossia and cleft palate with 100% penetrance in embryos examined after embryonic day 14.5. In Sox2 conditional knockout embryos, the oral epithelium failed to differentiate, as demonstrated by the lack of keratin 6, a marker of the periderm. Further examination revealed that the adhesion of the tongue and mandible expressed the epithelial markers E-Cad and P63. The expanded epithelia are Sox9-, Pitx2-, and Tbx1-positive cells, which are markers of the dental epithelium; thus, the dental epithelium contributes to the development of oral adhesions. Furthermore, we found that Sox2 is required for palatal shelf extension, as well as for the formation of palatal rugae, which are signaling centers that regulate palatogenesis. In conclusion, the deletion of Sox2 in oral epithelium disrupts palatal shelf extension, palatal rugae formation, tooth development, and periderm formation. The periderm is required to inhibit oral adhesions and ankyloglossia, which is regulated by Sox2. In addition, oral adhesions occur through an expanded dental epithelial layer that inhibits epithelial invagination and incisor development. This process may contribute to dental anomalies due to ankyloglossia.

The Subplate Layers: The Superficial and Deep Subplate Can be Discriminated on 3 Tesla Human Fetal Postmortem MRI

The subplate (SP) is a transient structure of the human fetal brain that becomes the most prominent layer of the developing pallium during the late second trimester. It is important in the formation of thalamocortical and cortico-cortical connections. The SP is vulnerable in perinatal brain injury and may play a role in complex neurodevelopmental disorders, such as schizophrenia and autism. Nine postmortem fetal human brains (19–24 GW) were imaged on a 3 Tesla MR scanner and the T2-w images in the frontal and temporal lobes were compared, in each case, with the histological slices of the same brain. The brains were confirmed to be without any brain pathology. The purpose of this study was to demonstrate that the superficial SP (sSP) and deep SP (dSP) can be discriminated on postmortem MR images. More specifically, we aimed to clarify that the observable, thin, hyperintense layer below the cortical plate in the upper SP portion on T2-weighted MR images has an anatomical correspondence to the histologically established sSP. Therefore, the distinction between the sSP and dSP layers, using clinically available MR imaging methodology, is possible in postmortem MRI and can help in the imaging interpretation of the fetal cerebral layers.

Multiphysics Coupling Method to Simulate the Friction Stir Welding Process

In In this work the methods are developed to perform simulations of the friction stir welding process using the ANSYS software working scheme, developing multiphysics couplings between computational fluid dynamics tools to Model the viscoplastic effect of the fluidity of the material when it is stirred by means of a solid tool modeled in the Transient Structure application that allows calculating the thermo-mechanical effects of the study process. The results show the validations corresponding to the modeled and experimentally performed analysis showing a lot of reliability in the proposed method. The torque reached in the process is maintained in the ranges of 14 Nm, the maximum temperature reached in the process was 540°C, this being 78.3% of the melting temperature of the material studied, having an adequate range for these studies.

Local kinetic processes determining macroscopic properties of interlinked magnetic flux tubes

<p>One of the most important transient phenomena affecting the solar wind-Earth’s magnetosphere coupling is non-steady dayside magnetic reconnection, observationally evidenced by a transient structure consisting of a bipolar magnetic-field component normal to the magnetopause. This signature, termed a flux-transfer-event (FTE), has been recently found to often consist of two interlinked flux tubes. The recent observations, particularly from the MMS spacecraft, showed a reconnecting current sheet between the interlaced flux tubes. However, local kinetic processes between the flux tubes have not been understood in the context of the broader FTE structure and evolution. An FTE observed by MMS on 18 December, 2017 comprised two flux tubes of different topology. One includes field lines with their ends connected to the northern and southern hemispheres while the other includes field lines that are connected to the magnetosheath (and ultimately the Sun). Evidence for reconnection occurring at the interface of the two flux tubes indicates how interacting flux tubes evolve into a flux rope having helical magnetic topology connecting either both to the Earth or being completely open. This study proposes a new aspect of how micro-to-meso-scale dynamics occurring within FTEs determines the macroscale characteristics and evolution of the structures.</p>