Differences in Alveolar Size in Inbred Mouse Strains

In this paper we examined structural differences in alveolar size among inbred mouse strains which are known to have significant differences in lung pressure-volume relations. Accordingly, we assessed whether the relative size or number of alveoli in the C3H/HeJ, C57BL/6J, and A/J strains are related to these lung volume differences. Lungs from each of these strains were fixed in situ and then excised for quantitative morphometric analysis of airspace chord lengths. Mean chord lengths (in microm) were significantly different (P < 0.0001) among the three strains, with the largest alveoli found in the C3H/HeJ mice (45 +/- 5), the smallest in the C57BL/6J mice (35 +/- 3), and intermediate in the A/J strain (38 +/- 2). These findings provide clear evidence that there are significant genetic differences in the lung structure among different mouse strains. However, since the A/J and C57BL/6J mice had similar lung volumes, there does not yet seem to be a clear link between the macroscopic manifestations of the microscopic structure. We speculate that these structural differences might have significant influence on several mouse models of lung disease, especially those involving the development of emphysema.