The identification of the effects of xenobiotics on development and tissue differentiation is a major branch of toxicology. The course will provide the students with current knowledge on the basis of the biological, molecular and genetic mechanisms that take place from gastrulation to organ formation and tissue differentiation. Particular emphasis will be given to studies in model organisms. Therefore, the course will focus on the developmental programs of mouse and zebrafish, and their application to study the effects of toxic agents and on state-of-the-art technologies to study the effect of xenobiotics in living animals (e.g. in vivo imaging) as well as in autoptic tissues and provide the basis for the understanding of the exploitation of these model organisms for small-scale and high-throughput analyses aimed at the quantitative and qualitative analysis of toxicant effects in living organisms.