Interalveolar pores in mouse lung. Regional distribution and alterations with age.

Quantitative analysis of the regional distribution of interalveolar pores in the lungs of BALB/c mice 1 to 28 months of age (n = 25) was performed by scanning electron microscopy. In all the age groups examined, the subpleural and peribronchiolar alveoli had significantly more pores than the midzonal region (p < 0.01). No significant changes were noted in the number of pores per alveolus between 3 and 26 months of age in the midzonal, peribronchiolar, and subpleural alveoli. We concluded that (1) intralevolar pores are regionally distributed in the lungs of BALB/c mice by 3 months of age, and (2) the number of pores do not significantly change with increasing age during the first 26 months.