Surface rendering method was used to visualize the lung, which allowed a clear depiction of complex spatial relationships and provided a strong space sense. By manually selecting the value of the reconstruction iso-surface, 3D models of tissues in the mouse chest cavity were obtained. All 3D models can be varied in size and rotated in real time to facilitate a detailed assessment of each structure (Video S1). As shown in Figure 3 , a surface rendering view of lung is displayed. The three-dimensional relationships among bronchiole, alveolar duct and alveoli were all visible. Through the segmentation of the CT slices, three models were acquired. Figure 3A and B give an overview of chest which combines ribs, bronchi, bronchioles, and alveoli. Figure 3C focuses on the display of bronchi and alveoli. Figure 3D is the result of image segmentation; it highlights the bronchial tree. The virtual endoscope video is also provided in the supporting information (Video S2).