[Stereologic analysis of the respiratory zone of the lungs of the laboratory rat and man during aging].

By means of stereological analysis methods, lungs of mature and ageing laboratory rats and those of human beings at the age of 21-40, 41-60 and further have been studied. During the process of ageing the fraction of nonparenchymatous structures increases, while that of parenchyma decreases. Architectonics of acini is described: the volume of central passages increases and the volume of alveolar air decreases. The form of the alveoli approaches the spherical one. The area of the internal surface and the alveolar volume increase. The total number of the alveoli and the area of the respiratory lining decrease. The total number of the alveolar capillaries does not change, however, the density of their distribution grows small. The area and volume of a separate segment of the alveolar capillaries grow large. The age rearrangement of the respiratory zone morphologically differs from the changes that are observed at the obstructive emphysema.