Structure of the Avian Lymphoid System

Our ability to understand the function, pathology and regeneration ability of an organ system is handicapped without knowledge of its normal structure. Electron microscopy and, later, immunocytochemistry made it possible to extend our knowledge of the structure of cells and the communication between them. These novel techniques helped to recognize the avian dendritic cells. Contemporary research on the structure of the lymphoid system contributed to recognition of the microenvironment and secretory functions of the primary lymphoid organs. Determining the histology of organs, using electron microscopy and immunocytochemistry of cells, will catalyze interactions between morphologists and immunologists to create novel ideas and hypotheses, and will result in a more comprehensive understanding of avian immunology. This chapter is a comprehensive immune-morphological report on the primary and secondary lymphoid organs of birds.