1. Physiological atresias represent temporal functionate structures that appear and disappear in various organs at different stages in embryonic development. 2. The phenomen of physiological atresia has its morphological and time characteristics in different organs and systems. The universal occurrence of the epithelial adhesion observed in the viscera and natural apertures in the body have functional significance for the embryo in its adaptation to the development in the amniotic medium. 3. Deviations in recanalization of fetal occlusions result in the appearance of congenital atresia and other defects in the development. This is grounded by some indirect evidences. 4. Detailed a knowledge of embryogenesis has clinical importance in explaining the observed congenital anomaly and for their diagnosis and correction.