This module will discuss the molecular and cellular principles that drive embryonic development, including the signals and signalling pathways that lead to the establishment of the body plan, pattern formation and differentiation/organogenesis. Lectures will cover a number of different model organism used in the study of development including plants and Drosophila, however there is a focus on vertebrate systems. The relevance of embryonic development to our understanding of human development and disease is a recurring theme throughout the module.