Figure 1 shows that naked eyes observed no significant increase
in the lung volume in the control group, and the surface
of the lung appeared smooth. Under the microscope, intrapulmonary
bronchial epithelial cells were intact. There was not
any inflammatory cell infiltrating into the bronchial wall, and
there was no expansion or collapse in the pulmonary alveoli.
There were also no hemorrhage and edema fluid in the alveolar
space. None or most of alveolar septum were not significantly
enlarged or infiltrated by inflammatory cells.