The structure of the Harderian and lacrimal gland ducts of the turkey, fowl and duck. A light microscope study.

The secretory ducts of the Harderian and lacrimal glands of the turkey, fowl and duck are similar in both structure and function. The single duct of each gland is lined by mucus-secreting epithelium. The epithelial cells vary from cuboidal to columnar, and goblet cells of three types are found. Type A, the most numerous, contain neutral mucopolysaccharides, type B have mixed acid and sulphated mucosubstances and type C, the least numerous, contain acid mucins. In both ducts glycogen is present in the lumen, but it occurs intracellularly only in the fowl up to seven days after hatching. Lymphocytes, either as diffuse tissue or as germinal centres, are found scattered along the length of the ducts. Some plasma cells and plasmablasts are also present.