ABSTRACT
This chapter briefly summarizes what is known about the orbital glands and to describe the interaction of these organs with the pineal as well as other endocrine glands. The Harderian gland was first described in 1694 by the Swiss physician Jacob Harder while studying the orbit of the deer, Dama vulgaris. The secretory units are constituted by one, two, or more types of secretory and myoepithelial cells. Indoles in the Harderian glands have been subject of numerous studies since Bubenik et al. The possible presence of melatonin in the Harderian glands of the Syrian hamster was first implied by the finding of Pevet et al. In this paper, a circadian rhythm in the activity of hydroxyindole-O-methyltransferase was found in male hamsters. Sexual differences in Harderian gland indole metabolism of the Syrian hamster are regulated by hormones, especially androgens. There have been only a few studies on indole metabolism in the Harderian glands of non-mammalian species.
