organogenesis /-jen″əsis/ [Gk, organon + genesis, origin] , (in embryology) the formation and differentiation of organs and organ systems during embryonic development. In humans the period extends from approximately the end of the second week through the eighth week of gestation. During this time the embryo undergoes rapid growth and differentiation and is extremely vulnerable to environmental hazards and toxic substances. Any interference with the sequential processes involved with organogenesis causes an arrest in development and results in one or more congenital anomalies. Also called organogeny. See also embryological development, prenatal development. −organogenetic, adj.
