A novel method for the collection of highly developmental murine immature oocytes

Abstract

Isolation of germinal vesicle (GV) or metaphase I (MI) oocytes from large antral follicles, using a 30 gauge needle, in mice is a common method for the retrieval of immature oocytes from ovaries. However, this method depends entirely on the experience and judgment of the investigator. It is possible that not all of the isolated immature oocytes are from large antral follicles nor necessarily represent the cohort of oocytes that would be perfectly developed and consequently ovulated upon hormonal stimulation. Here, we administered an FDA approved phosphodiesterase 3A inhibitor, named cilostazol, in superovulated mice to result in the ovulation of GV or MI oocytes, depending on time and frequency of administration. The presented method results in mice ovulating GV or MI oocytes, which can be recovered from the oviduct without the investigator's judgment mentioned above. This method does not only result in immature oocytes with high yield, health, synchronized maturation, and competence levels but also is time and labor efficient. It also permits for physiological selections of a cohort of immature oocytes that would be entirely developed and eventually ovulated, as opposed to the conventional method.•Complete superovulation•Administration of cilostazol at different times•Recovery of ovulated immature oocytes from oviducts