Production in vitro of mouse early pregnancy factor and purification to homogeneity

Early pregnancy factor (EPF) has been produced in vitro by culture of oestrous mouse oviducts and ovaries in RPMI, with the addition of prolactin and mouse embryo culture medium. The pooled harvested medium was then subjected to immunoabsorption, electrofocusing and gel filtration. A fraction was isolated with pI 6.83 and molecular weight 21 000 which was responsible for 90% of the recovered biological activity. It appeared to be homogeneous when analysed by high-performance gel-permeation chromatography. SDS treatment showed that the molecule could be split into 3 peptides of molecular weights 10 500, 7200 and 3400, the first having activity equivalent to the EPF component EPF-A from the oviduct, while the last two combined to give activity corresponding with the ovarian component EPF-B.