Figure 1

Comparative morphological changes in chicken embryo tracheal rings in vitro. (A) Microscopic observation (40 ×) of chicken embryo tracheal rings cultured in vitro for 3, 5, 7, and 8 days was performed. (1) In the uninfected group, at 8 dpi, there was normally developed chicken embryo tracheal rings. (2) In the infected group, at 5 dpi, there was atrophy and depression of the tracheal ring epithelial tissue. (3) In the infected group, at 7 dpi, the tracheal ring epithelial tissue was detached. (B–E) Morphological analysis of chicken embryo tracheal rings was performed by H&E staining. (B) A cross-sectional view of the chicken embryo tracheal ring in the uninfected group at 8 days is shown. (C) In the infected group, at 3 dpi, the cross-section of the chicken embryo tracheal ring began to degenerate, with mucosal atrophy. (D) In the infected group, at 5 dpi, there was further loss of cilia in the cross-section of the chicken embryo tracheal ring, necrosis of the epithelial cells, and the infiltration of inflammatory cells. (E) In the infected group, at 7 dpi, there was partial separation of epithelial cells from the lamina propria and detachment and perforation of the epithelial layer.