Fig. 1

Macroscopic and microscopic findings. a Gross image of the sow uterus, with multiple cystic structures of variable diameters attached to the serosa. b Detail of the cysts. Notice the transparent wall and clear fluid that fills the cysts. c Histologically, cysts were lined by a simple and flattened epithelium with no atypia, with the lumen filled with hyaline proteinaceous material (corresponding to fluid). The subepithelial lamina consisted mainly of collagen fibres. Insert: detail of the cysts lining epithelium. Externally, cysts are also lined by peritoneal epithelium. H&E. × 5 and insert × 80