Epithelial tissues exhibit diverse geometries to properly carry their role as barriers, ensuring proper transport and tissue integrity. While biochemical regulation of epithelial organization is well studied, the mechanical factors shaping 3D cell geometry remain less understood. In this thesis, I investigated how epithelial cell shape and tissue organization was influenced by cell density, confinement, substrate adhesion, and curvature. Using an encapsulation system where cells grow within spherical alginate capsules, I systematically varied mechanical parameters and tracked cell organization within tissues of increasing densities. I developed a custom 3D segmentation pipeline to extract over 20 geometric parameters per cell and reported that cell volume decreases with density prior to confluency, while tissue height appears tightly regulated. This height control depended on substrate properties, particularly the rigidity. Notably, we observed that all tissues showed apical-basal asymmetries, which were enhanced in tall tissues. These findings demonstrate the value of in dept morphological analysis to link tissue mechanics, cell geometry, and tissue architecture.