[Development of the nasal cavity and formation of the nostrils in human embryogenesis].

The development of nasal cavity was traced in human embryos. The identity in the primitive formation of the mouth cavity and that of the nasal cavity is stated. During embryogenesis, the primitive nasal cavities are demonstrated to change their position concerning the mouth cavity. Epithelial "cluster" formation in the area of the nostrils is examined: it appears in embryos of 16-19 mm long, is mostly prominent in embryos of 50-55 mm long, is absent in fetuses of 5.5 months old. By comparing the terms and dynamics in the development of epithelial adhesion in the larynx an the nostrils, the importance of these temporal structures for protecting the respiratory tract of the embryo from amniotic fluid is demonstrated.