How growth of a developing tissue is regulated is far from being understood. Tissue growth involves complex biological and mechanical processes that operate from the global systemic level to the local cellular level. The present work investigates two important growth-regulatory processes. The first part focuses on the mechanism by which the morphogen Dpp regulates growth and patterning of the Drosophila wing disc. In particular, it explores how wing disc growth is coordinated with the expansion of the Dpp gradient: a phenomenon that is termed scaling. The second part of this thesis tackles the dynamics, the role, and the mechanism of cell volume changes during mitosis of cultured and columnar epithelial cells. This work establishes assays and a set of analytic methods to study cell size and geometrical properties over time.