[Examination of the terminal respiratory tract for determining the relationship between the lungs and gestational stage in the perinatal period. Normal conditions].

The criteria of the gestational norm for the lungs on 28-30, 31-33, 34-37 weeks and in normal neonates are presented. The emphasis is placed on the structure of the terminal respiratory tract and on the connective tissue composition in the foetus. A sharp increase in the amount of elastic fibers and rapid lung maturation after the start of external respiration are noted. Lung alterations at the reanimation depending on the gestational period and relevant type of lung structure are described.