33. Patterns of Early Development

Though animals are dramatically diverse, the basic mechanisms of their development are similar across groups. This lecture examines the four earliest stages of developmentfertilization, cleavage, gastrulation, and organogenesis and outlines the processes involved in each. After fertilization, each stage involves a set of simple processes repeated over and over to produce the great diversity of cell types and structures found in a complex multicellular organism, and ultimately the diversity we observe across different kinds of organisms.