Histopathology of the lymphatic system in ascitic broilers

Histomorphologic changes of the lymphatic system of the liver and thoracic duct were examined in broiler chickens (from 32 to 37 days old). The diameters of lymphatic segments isolated from the thoracic ducts of ascitic and normal broilers were measured using an optical micrometer measurement system. The histopathological picture of the segments of lymphatic tissue showed lymphatic cysts bilaterally along the posterior vena cava. The hepatic capsule manifested oedema, thickening, and cellular proliferation. Microscopic changes in lymphatic vessels of the hepatic capsule included lymph embolism and lymphatic plasma retention in lymphatic cysts. In some cases distended lymphatic vessels exhibited protuberances and lymph leaked from the lymphatic cysts into the surrounding swollen and degenerated endothelial cells of the thoracic duct. Extensive endothelial cell loss was observed sometimes. Exfoliated fragments were also seen. Marked dilatation of thoracic duct, lymph embolism, leaking of lymph, oedema in some fibers, enlargement of spaces between fibers, swollen intimas, rupture, and bleeding of the thoracic duct were also visible.