Harderian glands of golden hamsters: morphological and biochemical responses to thyroid hormones.

Manipulation of circulating levels of thyroid hormones modifies Harderian gland structure and porphyrin concentrations in male and female golden hamsters. Specifically, thyroxine (T4) and triiodothyronine (T3) induce the morphological conversion of the Harderian glands of females to approximate those of the male. Further, porphyrin concentrations are markedly decreased by this treatment. This effect occurs in ovariectomized animals as well, indicating that the gonads are not involved. Suppression of thyroid function by potassium perchlorate (KClO4) drastically reduces Harderian gland weight in both males and females. However, KClO4 decreases porphyrin levels in the Harderian glands of females and increases it in the male. Concurrently, KClO4 also induces a morphological conversion of the Harderian glands of males to the female type. This effect is evident in photoperiods of either 14:10 (h) or 8:16 (h).