Modelling of epithelial growth, fission and lumen formation during embryonic thyroid development : a combination of computational and experimental approaches

Organogenesis is the phase of embryonic development leading to the formation of fully functional organs. In the case of the thyroid, organogenesis starts from the endoderm and generates a multitude of closely packed independent spherical follicular units surrounded by a dense network of capillaries. Follicular organisation is unique and essential for thyroid function, i.e. thyroid hormone production. Previous in vivo studies showed that, besides their nutritive function, endothelial cells play a central role during thyroid gland morphogenesis. However, the precise mechanisms and biological parameters controlling the transformation of the multi-layered thyroid epithelial primordium into a multitude of single-layered follicles are mostly unknown. Animal studies used to improve understanding of organogenesis are costly and time-consuming, with recognised limitations. Here, we developed and used a 2-D vertex model of thyroid growth, angiogenesis and folliculogenesis, within the open-source Chaste framework. Our in silico model, based on in vivo images, correctly simulates the differential growth and proliferation of central and peripheral epithelial cells, as well as the morphogen-driven migration of endothelial cells, consistently with our experimental data. Our simulations further showed that reduced epithelial cell adhesion was critical to allow endothelial invasion and fission of the multi-layered epithelial mass. Finally, our model also allowed epithelial cell polarisation and follicular lumen formation by endothelial cell abundance and proximity. Our study illustrates how constant discussion between theoretical and experimental approaches can help us to better understand the roles of cellular movement, adhesion and polarisation during thyroid embryonic development. We anticipate that the use of in silico models like the one we describe can push forward the fields of developmental biology and regenerative medicine

W.G. 4. AQUIFER ENGINEERING

The report of the COST ACTION 621 “Groundwater management in coastal karstic aquifers” is the result of the comparison and fusion of personal experiences of researchers coming from 15 european countries, which faced in their job many aspects both of the functioning and the managing of these karstic coastal aquifers. At the end of five years of meetings and visits held in towns and places of the 15 countries taking part to this COST ACTION 625, it has been written this report in the aim of fixing the work made and the experience carried on. On the other hand this report contains a very interesting and updated compilation of engineering methodologies adopted for groundwater exploitation in coastal karstic aquifer, and it presents many examples of catchment works, realized in european countries, of these methodologies. In particular this chapter 4 deals with different type of catchment works engineering. As a matter of fact in karst aquifers due to the general lack of surface water, groundwater exploitation is the only way to satisfy water demand, which is increasing in every coastal area, and usually surpasses the dynamic potential replenishment of the natural freshwater system. This fact causes a phenomenon named overexploitation, which is the origin of seawater intrusion. The engineering of catchment works in karstic coastal aquifers deals mainly about the problem of groundwater exploitation without starting seaweater intrusion and the consequent groundwater contamination