Neem (Azadirachta Indica L.) and Oocyte Quality

Mammalian ovary is a dynamic organ that is responsible for the production of competent oocytes required for successful fertilization and early embryonic development [1,2]. The meiotic competency folliocular is achieved within the follicular environment during final stages of folliculogenesis [3-7]. The achievement of meiotic competency starts in diplotene arrested oocytes, possessing germinal vesicle (GV) as well as nucleolus [1,5,8-12]. The diplotene arrest for such a long period is due to transfer of several molecules from encircling granulosa cells to the oocyte [1,6-8]. Pituitary gonadotropin(s) surge disrupt gap junction as well as cumulus-oocyte communication thereby transfer of meiosis inhibitory factors [13-15]. The interruption in the transfer of inhibitory molecules results in meiotic resumption of follicular oocytes in vivo in the presence of pituitary gonadotropin(s). The spontaneous resumption of meiosis can be achieved if cumulus-oocyte complexes are removed from ovarian follicles and cultured in appropriate medium for extended period of time [1,6-8]. Meiotic resumption from diplotene arrest occurs due to interruption in the transfer of inhibitory factors from surrounding granulosa cells to the oocytes under in vitro conditions [13-15]. Although meiosis resumes due to physical removal of encircling granulosa cells, oocyte becomes more susceptible towards in vitro culture conditions mediated apoptosis [16-20]. This is supported by observations that GV stage (immature) oocytes are more susceptible towards oxidative stress-mediated apoptosis as compared to metaphaseII (M-II) stage (mature) oocytes [9,10,16-20]. The achievement of meiotic competency not only produces a right female gamete but also enhances its ability to resist any adverse changes under in vitro culture conditions during various assisted reproductive technology programs.