Bilateral dimorphism of Loewenthal's gland in young male albino rats: an ultrastructural investigation

Androgen and estrogen receptors expression in the rat exorbital lacrimal gland in relation to ?harderianization?

The rat exorbital lacrimal glands (ELG) are particularly interesting for their biochemical and morphological sexual differences. Our histochemical and ultrastuctural observations confirm a phenomenon termed "harderianization" that occurs in the ELG of males and females at three months of age. The "harderianization" consists of the appearance of lipid foci in the ELG; this effect increases at six months of age only in the male glands, while it is not detectable in those of females. Histochemical tests for mucosubstances and proteins evidenced that while the secretory granules of male ELG are prevalently composed of sulphate substances, those of the female are composed of acid substances, and only a few cells positive to proteins were seen in the acinar epithelium of the glands. Moreover, we demonstrated by RT-PCR the presence of androgen and estrogen receptors in the rat ELG of both sexes. Androgen receptor transcript is always present in male and female ELG while the expression of estrogen receptor is not more detectable in the ELG of males at six months of life. In conclusion, our results suggest that estradiol may prevent the further lipid degeneration of the female ELG at six months of life. In addition, the disappearance of both the "harderian lipid" foci in the female gland and of estrogen receptor in the male gland indicates a probable involvement of estrogens in the phenomenon of "harderianization."