Abstract: Compounds of Formula I and methods of regulating the meiosis in a mammalian germ cell which method comprises administering an effective amount of the compound of Formula I to a germ cell in need of such a treatment.

Abstract: The present invention relates to the use of a new principle for improving the viability and pregnancy potential of oocytes and pre-embryos obtained in connection with in vitro fertilisation and pre-embryo transfer treatment. More specifically, improvement by raising the content of Meiosis Activating Sterols (MAS) in the medium where the in vitro fertilisation takes place. This is achieved by exposing and culturing one or more oocytes with spermatozoa in a culture medium comprising at least one meiosis activating sterol (MAS), MAS analogue, and/or an additive or additives capable of endogenous stimulation of the accumulation of at least one MAS. Preferred additives are FSH and EGF.