Before revision:  We show that anisotropic deformation of tissue and cells can arise from two distinct active cellular processes: generation of active stress in the tissue, and actively driven cellular rearrangements. These two active processes result in distinct cellular and tissue shape changes, depending on boundary conditions applied on the tissue.
After revision:  We show that anisotropic deformation of tissue and cells can arise from two distinct active cellular processes: generation of active stress in the tissue, and actively driven topological rearrangements. We find that these two active processes result in distinct cellular and tissue shape changes, depending on boundary conditions applied on the tissue.