Immunohistochemical evidence for the presence of vasopressin in the rat harderian gland, retina and lacrimal gland.

The presence of vasopressin in the Harderian gland, the retina and the lacrimal gland of the rat, has been examined immunohistochemically. After fixation in Bouin's solution, immunostaining is accomplished with the peroxidase-antiperoxidase method. In the retina, the immunoreactive vasopressin is almost exclusively restricted to the ganglion cell layer. In the Harderian gland, the immunoreactivity is localized in the epithelial cells of the excretory duct and restricted to the cytoplasm. In the lacrimal gland, the immunoreactivity is localized in the secretory cells of the acini and the intercalated ducts and the immunostaining is restricted to the cytoplasm surrounding the nucleus. The possible functions of vasopressin in these ocular structures are discussed.