The Expression Of Embryo Lewis Y Oligosaccharide In Different Culture Conditions

Objective: In order to find the factor improving the development of embryo in vitro by detecting the excretion of LeY oligosaccharide antigen in different culture conditions .To determine the relationships between "LeY or blastocyst score" and "implantation and pregnancy outcome" by using mouse embryo transplantation model, and then, find out the comprehensive factor to evaluate embryo quality.Method: 2-cell embryos were cultured to 8-cell,morulas and blastocysts respectively in three different culture systems(simple P1-BM sequential culture group, co-culture + sequential culture group, natural development in mouse reproductive tract). These embryos continued to be cultured for 4 hours in the 40ul microdrop culture medium separately. Then, we removed the embryos,collected these culture microdrops and detected the excretion of LeY oligosaccharide by Dot Blot method. Those of all removed embryos, having developed to blastocysts in vivo and getting a pre-implantation score of 3AA or 3BB, were transferred into the uterus of pseudopregnancy mice on the third day. 11 days later, we observed the implantation rates and compare the effect of the excretion of LeY oligosaccharide and blastocyst score on embryo imbedding ability. Results: 1,In P1-BM+endometrium group, embryos growth rates , after 8-cell stage, and blastocyst formation rates were higher than those in simple P1-BM group (P<0.05), however, there was no significant difference in embryo morphology between the two groups. 2,The LeY expression of the embryos in different growth phases: we couldn't observe the LeY oligosaccharide in the culture microdrops of only one 8-cell embryo being collected from three different culture systems, nevertheless, LeY could be detected in those microdrops containing 10 8-cell embryos, in addition, the 8-cell embryos in P1-BM+endometrium group excreted the most LeY oligosaccharide; LeY excreted by one morula or blastocyst could be observed, the LeY concentration in simple sequential culture group was lowest and the concentrations were no significant difference between the other two groups, namely, co-culture + sequential culture group and in-vivo group. 3,The in-vivo growth blastocyst implantation rate of LeY high expression group was higher than that of low expression group (P<0.01), except the influence of embryo morphology; the in-vivo blastocysts scored 3AA implanted more than those scored 3BB (P<0.05), taking into the condition of LeY excretion account; the blastocyst implantation rate of the LeY high expression and 3AA group was significantly higher than low expression and 3BB group (P<<0.01),but the difference in implantation rate between 3AA group and high expression group was not significant.Conclusion: 1,Co-culture + sequential culture system could aquire higher blastocyst formation rate than simple sequential culture system. The active effect of co-culture on embryonic development was more significant. 2,Embryos in early phase could excrete a small quantity of LeY; the quantity of blastocysts expressing LeY increased obviously, in addition, it had relation with the implantation rate, it can reflected embryo imbedding ability. 3,The interaction of endometrium and embryo could increase the expression of excretive form LeY, but the endometrium was not essential. 4,The amount of embryo autocrine LeY oligosaccharide might have predictable value to implantation potential, especially it is important in the choice of the embryos which had the same scores. In addition, the implantation rate would be improved greatly when both of them were considered.