In vitro maturation of human oocytes

Development of in vitro maturation, The history of in vitro maturation (IVM) of oocytes goes back to as far as the 1930s (1) to Pincus, Enzman, and Saunders who studied the maturation of mammalian oocytes including human oocytes in vivo and in vitro (1, 2). Pincus and his colleagues observed that when oocytes were removed from the follicles and cultured in the laboratory without hormones, they spontaneously resumed meiosis and progressed to the mature stage, metaphase II (MII), as they do in vivo. In 1965, Edwards (3, 4) described the kinetics of in vitro oocyte maturation both in animals – mice, sheep, cows, pigs, and rhesus monkeys – and in humans. He introduced tissue culture medium 199 (TCM-199) for IVM and showed that meiosis is resumed in 80 percent of immature oocytes independent of cycle day and gonadotropin support. He subsequently concluded that “human oocytes can be fertilized after maturation in-vitro.” In 1983, Veeck et al. reported two pregnancies resulting from in vitro matured oocytes (5). These morphologically immature oocytes were recovered from human menopausal gonadotropin and/or follicle-stimulating hormone (FSH) and human chorionic gonadotropin (hCG) primed cycles in an in vitro fertilization (IVF) program. Cha et al. published the first birth resulting from the fertilization of in vitro matured oocytes, which were harvested from an unstimulated ovary on cycle day 13 in an oocyte donation program (6). They also mentioned in the same report that immature oocytes were recovered from unstimulated ovaries both in proliferative and secretory phases.