1. The document outlines the early stages of animal development from fertilization through gastrulation and organogenesis. It describes the formation of the blastula and gastrula, and the three germ layers that give rise to organs. 2. Morphogenesis and cell differentiation are discussed, involving changes in cell shape, position, and adhesion guided by the extracellular matrix and cell signaling molecules. 3. The role of cytoplasmic determinants in vertebrate eggs in establishing the body axes and cell fates is covered, as well as inductive signals that influence gene expression and lead to structure development.