[Comprehensive study on the expression mechanism of the early pregnancy associated substances and the implication for embryo development--structural determination of early pregnancy factor molecule and analysis of its homologous peptides].

The human early pregnancy factor (EPF) has been solidly isolated under the conditions without loosing its rosette inhibition activity. The activity fraction has been purified as a glycoprotein with 24-30KD molecular weight. The peptide structure was determined in 16 amino acid sequences from N-terminal which was demonstrated to have a strong homology with a part of human epidermal growth factor precursor. This molecule has been identified from the thioredoxin homologous peptide originated from human placenta which has been recently reported as a EPF molecule by Clarke et al. The rabbit in vitro-perfusion experiments have been performed to elucidate the expression mechanisms of EPF activity. EPF has been first detected within 3 hours after fertilization in the local circulation of ovary and oviduct contained embryos. Although the embryo-derived platelet activating factor (PAF) has been known as another preimplantation factor, the exposure of synthetic PAF induced EPF activity. Many other factors should implicate to express the activity and biofunction of EPF. The datas of EPF activity on the human in vitro fertilization and artificial insemination cases suggested that it demonstrated the conceptive circumstances and that EPF might be implicated in some regurations for the pregnancy establishment.