Representative histological pictures of the infundibulum, magnum and uterus before, during and after the infection. A–I All pictures were taken using a 10× objective from 4-μm sections stained with hematoxylin and eosin. B During the acute phase of infection (4–10 days pi), replication of the virus in the infundibulum was associated with the occurrence of severe necrosis, edema and granulomatous processes in the mucosa of the organ. C In the chronic phase of the disease (70–80 days pi), birds with egg yolk peritonitis showed a profound alteration of the infundibulum architecture due to the presence of ectatic glands (asterisk), hyperplastic lymphocytic aggregates (arrows) and thinning of the mucosa. E, H Lesions in the magnum and uterus were rarely observed during the acute phase of the infection and were limited to heterophilic necrosis and edema (arrow heads), respectively. F, I A full restoration of the tissue integrity was observed for the magnum and uterus in all subjects, after 70–80 days from infection.