Effects of gel-embedded embryos on developmental competence of separated bovine blastomeres

This study aimed to examine how gel embedding compared with the Well-of-Well (WOW) system when culturing bovine separated blastomeres, in terms of developmental competence rates and blastocyst quality. We first optimized the gel-embedding method via culturing intact zygotes in either 1% agarose or 1% calcium alginate gel. Gel-embedded groups and control did not differ in development rates, but the 1% calcium alginate group was selected for subsequent experiments due to higher blastocyst recovery. The separated embryo group had higher potential for blastocyst production than the intact embryo group. Among separated blastomeres (2- and 8-cell), WOW and 1% calcium alginate did not differ in blastocyst formation rate, except between the 2-cell alginate and WOW groups, with the latter exhibiting the highest rate of blastocyst formation. Within the WOW system, the separated 2-cell embryo resulted in significantly higher rates of OPU (ovum pick-up)-derived blastocysts than the intact 2-cell embryo; however, the latter had more total cells than the former. In conclusion, the 1% calcium alginate gel can support cell growth of separated 2- and 8-cell bovine embryos during blastomere aggregation. Moreover, the gel-embedded technique is a suitable replacement for WOW in producing blastocysts from bovine separated blastomeres.