Decreasing alveolar size from apex to base in the upright lung.
D000818:Animals; D004285:Dogs; D006652:Histological Techniques; D066298:In Vitro Techniques; D008168:Lung / Q000033:anatomy & histology*; D011650:Pulmonary Alveoli / Q000033:anatomy & histology* / Q000502:physiology*; D012119:Respiration / Q000502:physiology*