Lymphoid cells in the Harderian gland of birds. An electron microscopical study

In the subepithelial layer of the Harderian gland of some birds, macrophages, lymphocytes, plasma cells, as well as granulocytes are found. These cells are often densely aggregated in the central regions of the lobules, while individual cells occur near the periphery. Pre-plasma cells form desmosome-like contacts with macrophages and junctional complexes with each other. The lymphoid cells are sometimes embedded in a dense homogeneous material, which is also found in the intercellular spaces of the secretory epithelium. The present findings are discussed with reference to immunological aspects.