Experimental Control of Morphogenesis in Embryonic Tissues

Embryonic development is a complex phenomenon where embryos construct three-dimensional organ-structures through dynamic cellular rearrangements and cell shape changes. The rapidly dividing epithelial cells spreading over the entire mass of the embryo, the extension of a frog embryonic tissue in the anterior-posterior direction or epithelial-to-mesenchymal conversions are such examples where embryonic cells are undergoing dynamic shape changes. Other events such as bottle-cell formation, blastopore closure, neural tube closure and cement gland formation are examples of dramatic cell shape changes that result is bulk tissue movements. Embryonic development is fundamentally a mechanical process; a developing embryo is shaped by the stresses operating on its mechanical structure. Current studies mainly rely on observations of endogenous cell shape changes and are thus limited by the occurrence of developmentally programmed events. Here we utilize electrical-stimulation, laser-ablation and nano-perfusion approaches to trigger cell shape changes and understand the signaling pathway for externally induced cell contraction. Cell contraction generally and apical cell contraction specifically are the initial steps for numerous morphogenetic events. In these studies we aim to understand the molecular, biochemical and mechanical aspects underlying cell shape change and the role of contractility during morphogenesis. We then refine the perfusion approach to create patterns of differentially responding cells using a precisely controlled spatiotemporal stimulation