Before revision:  Using the model, we uncover the dynamical behaviour that underlies passive relaxationand active contraction-elongation of a tissue . The present work provides an integrated scheme for understanding the mechanisms by which morphogenetic processes of each individual cell collectively lead to the development of a large tissue with its correct shape and size .
After revision:  Using the model, we uncover the dynamical behaviour that underlies passive relaxationand active contraction-elongation , and tissue shear flow. This study provides an integrated scheme for understanding the mechanisms by which morphogenetic processes of each individual cell collectively lead to the development of a large tissue with its correct shape and size .