Development of hatching blastocysts from immature human oocytes following in-vitro maturation and fertilization using a co-culture system

Recently, in-vitro maturation (IVM) of immature human oocytes recoveredfrom non-stimulated follicles has been applied in the treatment ofinfertility. However, in previous reports, very few embryos cultured inconventional medium have reached the expanded blastocyst stage followingin-vitro maturation and fertilization (IVM/IVF). The objective of thisstudy was to investigate whether the developmental competence of humanembryos following IVM/IVF could be enhanced by the use of a human ampullarycell co-culture system. Immature human oocytes were aspirated from smallfollicles at Caesarean section and then cultured in medium containing humanmenopausal gonadotrophin for 36 to 48 h, followed by insemination. Zygoteswere randomly cultured either in conventional culture medium alone or inthe co-culture system. Of 48 embryos cultured in conventional medium alone,all arrested at the 2-16- cell stage on day 3 after insemination. Of 46embryos cultured in the co-culture system, 26 embryos (56.5%) arrested atthe 2-16-cell stage. Six embryos (13%) developed to the morula stage.Fourteen embryos (30.4%) developed to expanded blastocysts and twoblastocysts were hatching on day 7 after insemination. We conclude thatco-culture significantly enhances the development of blastocysts in embryosresulting from IVM/IVF.