EN
This review article deals with the current knowledge on the role of oestrogens in the regulation of reproductive tract functions in the boar. Boars exhibit high amounts of oestrogens in blood plasma and semen. The predominant oestrogen is the conjugate and free oestrone. Oestrogens are synthesized in the boar only by Leydig cells, but not by Sertoli cells and germ cells. Oestrogen receptors are expressed in the testis (Leydig cells, Sertoli cells, peritubular myoid cells, and germ cells) and the epidydymis. These hormones influence the development and function of the reproductive tract and play an important role in the regulation of spermatogenesis. Environmental oestrogens, particularly mycotoxin zearalenone, may cause reproductive disturbances in boars. Seminal oestrogens seem to influence reproductive functions in the female pig, such as sperm transport in the genital tract and the occurrence of ovulation. Further investigations are needed to clarify the role of oestrogens in the reproductive tract of the boar.