ABSTRACT
In 1935, Pincus and Enzmann found that rabbit oocytes, when liberated from Graafian follicles, would undergo spontaneous meiotic maturation in vitro11. Edwards demonstrated in 1965 that human oocytes removed from follicles could mature in medium supplemented with serum12. The first human birth resulting from IVM was reported by Cha et al. in 19912. They obtained immature oocytes from oophorectomy specimens. After maturation in vitro, the oocytes were donated to a woman of premature menopause, and a set of triplets was born. In 1994, Trounson et al.13 reported the first birth from IVM in PCOS women, and he developed a special aspiration needle for immature oocyte retrieval. However, the maturation rate of human IVM was about 30-50%2,14,15, which was much lower than that of other species, and the pregnancies resulting from IVM were limited. In addition, Trounson et al.16 demonstrated that the in-vitro matured human oocytes had reduced developmental competence. The poor outcome of human IVM was thought to be at least partly due to abnormalities of cytoplasmic maturation in in-vitro matured oocytes. Several treatment modalities have been proposed to improve the outcome of human IVM.
