The first major event in organogenesis is?

The first major event in organogenesis is the formation of the three primary germ layers: ectoderm, mesoderm, and endoderm, which occurs during the gastrulation phase of embryonic development. These layers give rise to all the organs and tissues in the body. Following gastrulation, organogenesis progresses through the differentiation and morphogenesis of structures from these germ layers. This complex process ultimately leads to the development of functional organs and systems.