respiratory alveolus morphology trait macrophage morphology trait alveolar macrophage morphology trait Any measurable or observable characteristic related to the shape, structure, color, or pattern of the round, granular, mononuclear phagocytes found in the alveoli of the lungs which ingest small inhaled particles resulting in degradation and presentation of the antigen to immunocompetent cells. Trait.ontology VT:0008245