Luteal phase start of low-dose FSH priming of follicles results in an efficient recovery, maturation and fertilization of immature human oocytes

In this prospective study we investigated whether the maturation and fertil ization of immature oocytes can be improved by administration of recombinan t follicle stimulating hormone (rFSH) starting in the late luteal phase in two groups of women: group 1 (n = 6) women with regular menstrual cycles; a nd group 2 (n = 6) women with irregular cycles and polycystic ovaries (PCO) on ultrasound examination. Low-dose (37.5 IU) rFSH was commenced 11 days a fter LH surge during a spontaneous menstrual cycle and on the ninth day of progesterone administration in an irregular cycle, Recombinant FSH was cont inued until the leading follicle was approximately 10 mm in diameter, The o ocytes were retrieved after withdrawing rFSH for 2-5 days. In total, 136 oo cytes were recovered (group 1, 67 oocytes; group 2, 69 oocytes), Nine of th e oocytes from PCO women were atretic at retrieval. Oocytes complete with c umulus cells were cultured for 44 h in complex tissue culture medium supple mented with gonadotrophins and fetal calf serum, After maturation, the cumu lus cells were removed and metaphase II oocytes were injected with spermato zoa. Respectively, the oocyte maturation and fertilization rates were 64 an d 72% in group 1, and 78 and 57% in group 2 (not significant). After fertil ization, the zygotes (group 1, n = 22; group 2, n 11) and cleavage stage em bryos (group 1, n = 9; group 2, n = 15) were frozen in propanediol, All wom en except one (11/12) had approximately five zygotes or cleaved embryos fro zen. The viability of in-vitro matured frozen-thawed embryos was generally poorer than that (81%) seen after conventional intracytoplasmic sperm injec tion, with 61% survival in group 1 and 23% in group 2, Fifteen embryo trans fers resulted in one miscarriage at 6 weeks gestation, The late luteal star t of low-dose rFSH yielded a good number of immature oocytes in women with both regular and irregular cycles. Two out of three of these oocytes mature d and fertilized. However, cryosurvival of the zygotes and cleaved embryos was unsatisfactory and thus cryopreservation of in-vitro matured embryos ma y not be an optimal procedure.