Spherical alveolar shapes in live mouse lungs

Understanding how the alveolar mechanics work in live lungs is essential for comprehending how the lung behaves during breathing. Due to the lack of appropriate imaging tools, previous research has suggested that alveolar morphologies are polyhedral rather than spherical based on a 2D examination of alveoli in fixed lungs. Here, we directly observe high-resolution 3D alveoli in live mice lungs utilizing synchrotron x-ray microtomography to show spherical alveolar morphologies from the live lungs. Our measurements from x-ray microtomography show high sphericity, low packing density, big alveolar size, and low osmotic pressure, indicating that spherical alveolar morphologies are natural in living lungs. The alveolar packing fraction is quite low in live lungs, where the spherical alveoli would behave like free bubbles, while the confinement of alveolar clusters in fixed lungs would lead to significant morphological deformations of the alveoli appearing polyhedral. Direct observations of the spherical alveolar shapes will help understand and treat lung disease and ventilation.

Automated summary

By using synchrotron x-ray microtomography, we directly observed high-resolution 3D alveoli in live mice lungs and showed that they have spherical morphologies. Our measurements indicated that the alveoli in live lungs are spherical in shape, with low packing density, large size, and low osmotic pressure. In contrast, alveoli in fixed lungs appear polyhedral due to the confinement of alveolar clusters. The observation of spherical alveolar shapes will contribute to the understanding and treatment of lung diseases and ventilation.