Plasma cells in the avian Harderian gland and the morphology of the gland in the rook

Abstract

Plasma cells occur in the Harderian glands of 32 species of birds investigated. They are found in the interstitium of the gland among the primary and secondary tubules. In the fowl, quail, and turkey and to a much lesser extent in the duck, their numbers increase with age. Other cells of the lymphoid series were only rarely seen. Foci of lymphocytes were encountered in few Harderian glands. Mott cells (Russell-body-containing plasma cells) occur among the plasma cells of all avian Harderian glands. Their numbers follow the pattern of plasma cell numbers.The rook Harderian gland has been studied and compared with other avian Harderian glands of similar morphology. Macroscopically it is a uniform structure but histologically it is composed of two lobule types. Type I lobules are compound tubuloacinar structures with a large plasma cell population in the interstitium. Type II lobules are compound tubular and have no plasma cells. The rook Harderian gland forms the "type specimen" for a third category of avian Harderian glands. The other two kinds may be compared with that of the fowl (type I) and with that of the duck (type II).