Effects of rhFSH dose on ovarian follicular response, oocyte recovery and embryo development in rhesus monkeys

The objective was to study the effects of dose of recombinant human follicular stimulating hormone (rhFSH) for ovarian stimulation in rhesus monkeys. Nineteen pubertal and 109 adult female rhesus monkeys were given 37.5, 18, or 9 IU of rhFSH twice-daily for 8 days (total of 600, 300, or 150 IU of rhFSH per cycle, respectively; designated Regimens 1, 2 and 3). Ovarian responses were assessed with ultrasonography, serum concentrations of E2 and FSH, and by in vitro developmental potential (following IVF) of retrieved oocytes. Regimen 1 had more monkeys with very large follicles (diameter>8 mm) than Regimen 2 (P<0.05), which impaired development potential. However, there were no differences between Regimens 1 and 2 in oocyte recovery, whereas Regimen 3 did not elicit superovulation. The developmental potential of embryos obtained from Regimen 2 was higher than that of Regimen 1, as determined by culture to the blastocyst stage in vitro (proportion of blastocysts relative to collected MII oocytes was 55.8% versus 36.8% in pubertal and 63.8% versus 44.2% in adult monkeys; P<0.05 for each), and the results of embryo transfer from Regimen 2 were acceptable. In conclusion, we inferred that the optimal rhFSH dose for ovarian stimulation in rhesus monkeys was a total of 300 IU; this dose should be efficacious for ovarian stimulation as the quality or recovered oocytes was higher and the risk of overstimulation was reduced.