Hypotaurine Requirement for In Vitro Development of Golden Hamster One-Cell Embryos into Morulae and Blastocysts, and Production of Term Offspring from

Almost 30 years after the first successful in vitro fertilization (IVF) in golden hamsters (Mesocricetus auratus), we report that IVF hamster embryos can develop in a chemically defined, protein-free culture medium into morulae and blastocysts, and produce normal offspring after transfer to recipients. When examined 96 h post-insemination, 82 % (160/200) of IVF ova had cleaved to at least 2 cells, 55 % (97/200) had developed beyond the 4-cell stage, and 22 % (38/200) had developed into morulae/ blastocysts. In vitro development of IVF embryos to 8 cells was absolutely dependent on hypotaurine. Twenty living offspring were produced from transfer of IVF embryos to recipients, with an overall success rate of 5 % and 17 % for oviductal (2-cell) and uterine (8-cell/morulae) transfers, respectively. In vivo-fertilized pronucleate embryos collected 3 h after egg activation were less able to develop in vitro than embryos collected only 6 h later, revealing a critical influence of the oviduct within the first hours of embryo development. Hypotaurine partly compensated for the decreased oviductal exposure of early 1-cell embryos. Establishment of a key role for hypotaurine in hamster embryo development, support of WF embryos to morula/blastocyst stages in vitro, and production of living offspring after IVF embryo transfer are significant steps towards the goal of obtaining comparative data on preimplantation embryogenesis. INTRODUC11ON Gametes of the golden hamster have been widely use