Adiposity of the B6 Mouse Lung

In biomedical research, mice are studied using a variety of techniques that require a baseline knowledge of microscopic anatomy, these include histochemistry, immunohistochemistry and immunofluorescence. Many biomedical personnel lack this background in their training. The lung is primarily composed of two zones: the conducting zone (airways) and the respiratory zone (alveoli). Morphologic differentials for alveolar structures are few in the lung, but in our experience adipose tissues in the lung can be a source of confusion and misinterpretation. In this study, we examined lungs from adult B6 mice (>3 months, n=16, female) that were obtained from de‐identified archival control tissues (UI Comparative Pathology Laboratory) to define lung adiposity. White adipose tissues (WAT) were detected in all lung samples (100%, 16/16). WAT was often seen as small aggregates of 5–15+ adipocytes embedded in loose connective tissue adjacent to large airways/vessels. In sites of smaller airway branching, WAT was rarely detected and usually only as a few solitary adipocytes. WAT adipocytes were distinguished from alveolar structures by their location, significantly reduced cellularity, and residence often in a collagenous matrix. Brown adipose tissues (BAT) were not observed in this survey. We have characterized the localization and appearance of adipose tissue in the lungs of female B6 mice. Awareness that WAT is present in lung tissues along with knowledge of its distinguishing features versus alveoli can help investigators make more clear and accurate interpretations of the lung data. Support or Funding Information NIH