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CSB Seminar – Professor Alfonso Martinez Arias
October 18 @ 3:00 pm - 4:00 pm
Department of Genetics
“The Cellular Basis of Axial Elongation in Mammalian Embryos”
3:00-4:00 p.m. at the Medical Sciences Building, Room 2172
A central feature of all embryos is their axial organization which endows masses of cells with spatial coordinates to organize tissues and organs. The most obvious of these is the anteroposterior organization which usually results in an elongated structure along which there are different specializations and the process of gastrulation appears to be the fuel of this organization. A survey of different embryos reveals that these structures arise from the organization and proliferation of cellular masses and that there are two modalities of this process. In one of them, characteristic of many anamniote embryos e.g fish and frogs, all cells necessary for the elongation are present before gastrulation, and most of axial elongation results from a reorganization of these cell ensemble. On the other hand amniote embryos e.g birds and mice, do not have enough cells before gastrulation and, in these organisms, axial extension is associated with proliferation. Mammalian embryos are an extreme of these second modality and undergo proliferation and patterning simultaneously. Surprisingly in these embryos it has been observed the existence of stem/progenitor cells that fuel axial elongation and act as progenitors of both mesodermal and neural precursors. We have been using Embryonic Stem cells in a combination of 2D and 3D culture systems to study this fundamental process and I shall be discussing how heterogeneities at the single cell level are transformed into coherent tissues during axial elongation.