[Studies on the mechanism of the onset of menstruation (author's transl)].

It has recently been demonstrated that prostaglandins (PGs) play roles in human reproduction, especially in ovulation and menstruation. The purpose of this study is to elucidate the mechanism of the action of PGs upon the onset of menstruation. By measuring the concentration of PGs in human endometrium from the women with normal menstrual cycles, PGF2 alpha was present in large amounts in late luteal phase. The activity of PG-synthetase and phospholipase A, which are key enzymes of PG-biosynthesis, also increased in late luteal phase. PG-receptor which is thought to be important to biological action of PGs showed no remarkable change throughout human menstrual cycle. These studies clarify the possibility that there is apparent correlation between the onset of menstruation and PGs.