Culture media for mouse oocyte maturation affect subsequent embryonic development

Abstract

These experiments were done to determine whether the culture medium used for the spontaneous maturation of mouse oocytes can affect the subsequent capacity of the ova to become fertilized and complete preimplantation development in vitro and development to live young. Oocytes obtained from antral follicles of gonadotropin‐primed immature mice underwent spontaneous maturation in control medium, i.e. Eagle's Minimum Essential Medium (MEM) supplemented with 5% fetal bovine serum, or in one of eight different media which were also supplemented with serum. All of the ova were fertilized in Whitten's medium and were assessed for cleavage to the 2‐cell stage and for further preimplantation development to blastocysts during culture in Whitten's medium. Three of the eight media used for oocyte maturation improved the capacity of the ova to develop to the blastocyst stage when compared with the control: Waymouth MB 752/1, MEM with non‐essential amino acids, and MEM Alpha; Waymouth medium promoted the highest frequency of development of ova to the blastocyst stage. Moreover, the blastocysts derived from oocytes that matured in Waymouth medium contained more cells than blastocysts derived from oocytes that matured in control medium. Although BGJb medium promoted the cleavage of eggs to the 2‐cell stage when present during oocyte maturation, it had a detrimental effect on their subsequent preimplantation developmental capacity. Following transfer to foster mothers, more 2‐cell stage embryos developed to live young after oocyte maturation in Waymouth medium (21%) than in control medium (13%). It is concluded that the medium used for oocyte maturation in vitro can affect processes involved in the subsequent development of the eggs and that, of the media tested, Waymouth MB 752/1 promoted the highest capacity for embryo development of maturing mouse oocytes.