Potent and stage-specific action of glutathione on the development of goatearly embryos in vitro

The effect of glutathione (GSH) addition on the development of 1- or 2-cell goat early embryos in vitro was examined. Embryos were collected from supe rovulated Korean black goat (Capra hircus aegagrus) and cultured for 6 days in synthetic oviduct fluid medium supplemented with either bovine serum al bumin (BSA) or serum. Without GSH addition, almost all embryos could not de velop beyond 8- to 16-cell block. However, GSH addition greatly improved in vitro development of early embryos to blastocyst stage, and its action was highly dependent on the presence and source of proteins supplemented into the culture medium. Among the protein-supplemented cultures, GSH effect was most prominent in 10% FBS-supplemented culture, in which the proportion (9 1%) of blastocysts developed from early embryos was much higher than that o f BSA(42-64% depending on its content) or goat serum (GS)-supplemented cult ures (21%), or even than that of somatic cell-supported co-culture (60%). A s well as in terms of the morphological development, mean cell number of bl astocysts (185 +/- 12) developed from FBS condition was significantly highe r than that of blastocysts developed from any other culture conditions and moreover comparable to that of blastocysts developed in vivo (190 +/- 9). T he viability of these blastocysts was finally confirmed by their term devel opment (6/12) from embryo transfer. To delineate action time of GSH during embryo development, GSH was treated at 1-day intervals through 6-days cultu re periods excepting the last day. In the GSH-treated embryos at day 3 of c ulture, which corresponds to the time of in vitro 8- to 16-cell block stage , the proportion of blastocyst was markedly increased up to 77% of cultured embryos and conversely that of the arrested embryos was decreased to 7%. I n the embryos treated later, however, their developmental potency decreased abruptly. Therefore, these results clearly demonstrated that GSH could gre atly improve the in vitro development of goat early embryos by specifically acting on the 8- to 16-cell block stage during in vitro development, sugge sting that GSH may be one of the important regulators on the development of goat embryos in vivo. (C) 2000 Wiley-Liss, Inc.