A view of three dimensional unit structures of alveoli in peripheral lung

Purpose: To find 3D unit structures of alveoli and alveolar ducts in peripheral lung, magnified 3D print of the lung specimen was made by micro focus CT. Those 3D images may not be shown by series of microscopic histological slides images. Method and Materials: The 3D printed 40 times magnified peripheral lung model based on the inflated fixed lung specimen with virtual image of micro focused CT was used to analyze the unit structure. Virtual peripheral lung tissue image was obtained by originally created application. Results: Naked eye view from respiratory bronchiole to the alveolar duct ring by magnified 3D printed alveolar tissue specimen model showed circular ring layout of mostly 6 alveoli between the next alveolar duct ring. The unit was consisted of circular layout of 5 to 7, mostly 6 alveoli. Units attached one and after, continuously as the alveolar duct. Distribution of numbers of alveoli on the unit revealed, a unit consisted of 5 alveoli 5.7%, 6 alveoli 91.4%, and 7 alveoli 2.9%, (n=35). On the dividing part of the alveolar duct, surrounding air space elements were consisted with 5 alveoli and an alveolar duct space, total of 6 elements. Summary: Circular layout of 6 alveoli surrounding the alveolar duct was found as a unit structure of alveoli on the magnified 3D printed model. This method realized naked eye visible pathological changes in COPD and other peripheral lung diseases.