Bisection and aggregation of embryos by biotechnological technique.

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l.Aggregation of mouse embryos Mouse chimaeras were produced from 4-, 8-, 12-16 cell stage embryos by the aggregation method. Specific relation was not recognized between cell stage and coat color. Frozen-thawed aggregated embryos were cultured in vitro and transferred to recipient. Live young were obtained from these embryos.2.Aggregation of sheep and goat embryos Production of a interspecies chimaeras was attempted by the aggregation of three sheep and one goat embryo. Two aggregated embryos were produced but were not transferred because the recipient sheep did not come to heat, hence, were not suitable to be use as recipient.3.Bisection of mouse embryos Decompacted mouse molurae were bisected with a fine needle and 69% of these embryos developed to eu-blastocysts after in vitro culture. Protein electrophoresis from bisected embryos showed similar pattern with those of normal embryos. However, abnormality in the microstructure was observed in the bisected embryos. And there was a decrease in the outgrowth of trophoermal cells and number of ICM cells. In addition, a decrease in the differentiation potential was also observed. From the above results, it was suggested that in bisected embryos cell division potential was maintained but damage in the cell differentiation potential to form tissue of fetus occurred because of the low cell number of ICM.4.Bisection of bovine embryos Sixty five bovine morulae and blastocysts were bisected. Chromosomal analysis from one- half of these bisected embryos were done and 38.5% of these half embryos were able to sexed. Calf born from bisected embryos that had been sexed by chromosomal analysis. From the above results, it was suggested that the production of chimaeras, by aggregation of half sexed embryos can be used as a basic study about sex differentiation.