Fig. 1.

Histopathological observation of lungs and spleens. Tissue sections from horses infected with EIAV_DLV121 (A and B) or EIAV_LN40 (C and D) and uninfected negative controls (E and F) were stained with hematoxylin and eosin (H&E). Arrowheads indicate alveolar wall thickening; and arrows indicate severe histological inflammation and the emergence of macrophages, cell degeneration and necrosis of the alveolar walls (C). Arrowheads indicate serious hyperemia in the red pulp; and arrows indicate necrotic zones of variable sizes that appeared in the white pulp (D). The magnification of the lung is 100× and that of the spleen is 100×.