Dose-response-relations after application of FSH: Follicular growth and results of superovulation

Dose-response-relations were investigated after application of FSH in superovulatory treatments. Results were recovered from basic experiments and from a clinical study. Starting with low FSH doses, the number of ovulations increased when FSH dose was increased. The number of ovulations reached a plateau and then decreased when FSH doses were further increased above an optimum. High doses of FSH can suppress ovulations completely. We conclude from our results that at least two mechanisms are responsible for suppression of ovulations. The first mechanismen consists of high FSH doses increasing progesterone concentrations prior to ovulation. Under these circumstancis estradiol is not able to induce LH peak. As a consequence ovulations are suppressed completely. Moreover, follicles do not, or in a limited number, respond to LH peak. We speculated that dysregulation in the cells of the follicular wall is the reason for this. It is possible to conclude that FSH doses above an optimum are not able to increase number of transferable embryos above the actual limit of 6 to 8 embryos per donor.