The culture of pig oocytes in minimal medium, and the influence of progesterone and estradiol-17beta on meiotic maturation.

Pig oocytes, with (intact) or without (denuded) adhering granulosa cells, were cultured for 33 to 35 h in minimal culture media containing bovine serum albumin and either progesterone or estradiol-17beta or both steroids. The incidence of maturation for intact oocytes in minimal medium was comparable, if not superior, to that observed by other investigators using complex culture media. No statistically significant stimulation of maturation by progesterone was observed for either intact or denuded oocytes. Estradiol-17beta at concentrations of 1.0 and 10.0 mug per ml inhibited the maturation of denuded oocytes, but the inhibition was overcome either by including progesterone in the medium or by subsequently culturing the inhibited oocytes in steriod-free medium. Chromosomal examination of air-dried oocytes indicated that intact and denuded oocytes cultured either in progesterone or estradiol-17beta exhibited an increased incidence of diploidy and hyperhaploidy at telophase I and metaphase II, but that oocytes cultured in media containing both progesterone and estradiol showed a higher incidence of normal haploidy than did control oocytes.