The novel histological evidence of the blood-spleen barrier in duck (Anas platyrhynchos)
Xuejing Sun1, Enxue Liu1, Taozhi Wang1, Qian Zhang2, Ping Yang1, Nisar Ahmed1, Qiaoya Zhao1 and Qiusheng Chen1
1MOE Joint International Research Laboratory of Animal Health and Food Safety, College of Veterinary Medicine, Nanjing Agricultural University and 2Key Laboratory of Antibody Techniques of Ministry of Health, Nanjing Medical University, Nanjing, Jiangsu Province, P.R. China
Offprint requests to: Prof. Qiusheng Chen, College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, Jiangsu Province, 210095, P.R. China. e-mail: chenqsh305@njau.edu.cn
Summary. To identify the existence and composition of the blood-spleen barrier (BSB) in ducks, the microanatomical structures of the duck spleen were investigated by light and transmission electron microscopy, silver staining, enzymatic histochemistry and intravenous injection of ink. The endothelial cells of the sheathed capillaries were cuboidal-shaped and surrounded by an ellipsoid consisting of reticular cells, similar to high endothelial venules (HEVs). After ink injection, carbon particles were initially restricted to the ellipsoid and later trapped in the periellipsoidal lymphatic sheaths (PELS), and then transferred to the periarteriolar lymphatic sheaths (PALS) and splenic nodules over time. Reticular fibers were primarily distributed at the basement membrane of the sheathed capillaries and the periphery of the PELS. Macrophages were primarily distributed at the border between red pulp and PELS. These results suggested that the BSB was present in the ellipsoid and PELS and consisted of the mechanical barrier composed of endothelial cells of the sheathed capillaries, reticular cells and reticular fibers and the biological barrier composed of ellipsoid-associated macrophages. In conclusion, the BSB was identified in the duck spleen for the first time, including cuboidal endothelial cells, ellipsoid-associated macrophages, reticular cells and fibers, and resisting circulating pathogen invasions. The study of BSB in ducks provides a theoretical foundation for the structural composition of the avian immune system. Histol Histopathol 34, 33-45 (2019)
Key words: Duck, Spleen, Blood-Spleen Barrier, Ellipsoid
DOI: 10.14670/HH-18-019