Effects Of Taurine, EDTA And Steroid Hormones On The Development Of Mouse Embryos In Vitro

In order to improve the cuture system of mammal embryo and advance the quality of embryo in vitro, the effects of taurine and ethylenediaminetetraacetic acid (EDTA) , estrogen (E2) and progesterone (P) on preimpiantation development of mouse embryos in vitro were examined and the quality difference of blastocysts from in vitro and in vivo by blastocyst staining and embryo transfer was evaluated.The addition of taurine and EDTA to Ml6 medium succeeded in overcoming the 2-cell block of mouse embryos in vitro and supporting the development of embryos to the blastocyst stage. The percentage of blastocysts in Ml 6 medium with both taurine and EDTA (73.6+2.4%) was significantly higher than that in M16 with EDTA and taurine alone (60+1.0% and 61.9+2.0%, respectively) . The change pattern in the cell parameters (inner cell mass, ICM; total cell numb,TCN) of the three groups was the same as the blastocyst formation rate.Experiments were carried out in mice to culture 1-cell embryos in the mM16 mediums containing different concentration taurine (0 mM, 2.5 mM, 5 mM, 10 mM, 50 mM, 100 mM, 150 mM, 200 mM ), which revealed the following: there was no difference in the blastocyst rate on Day 5 in the mediums containing 0, 2.5, 5, 10mM taurine (82.7%, 87%, 89%, 87.8%, respectively) ; whereas the blastocyst rates respectively declined to 76% and 51% when 50 and 100mM taurine; embryos could but develop to 8-cell and 2-cell stage respectively when 150mM and 200mM. The average total cell number of biastocysts when 5 mM taurine (65.7 + 2.4) was significantly higher than that in all the other concentrations (PO.05) . This suggested that 5 mM taurine was most suitable for the development of mouse embryos in vitro.The blastocyst rates on Day 5 of mouse 1-cell embryo cultured in mM16 added with estrogen and progesterone (93% ) was significantly higher than that of mM 16(87.67%) and mM 16 added with estrogen or progesterone alone(91 % and 90.4%, respectively), and there was no difference in the latter three groups. Although the cell parameters (ICM and TCN) of blastocysts of both groups differed significantly (P<0.05) , the mMl 6+E2+P group was the closest to the in vivo group , and those of the mM16 group were the lowest.To select the best mouse blastocysts resulting from mM16, mM16+E2, mM16+P and mM16+E2+P mediums,and from IVF-IVC (in vitro fertilization and in vitro culture) in HTF medium, and from in vivo was for embryo transfer. The result after the embry transfer was the following: the implantation rates and birth rates of mM16+E2+P group (82.67% and 34.67%,respectively) were the most closest to those of the in vivo group (90.67% and 82.67%, respectively) , whereas those of the IVF group were the lowest, and the other ones was between the mM16+E2+P group and IVF group. Except the in vivo group (16. 18% ), the abortion rate of the mM16+E2+P group was the lowest (45.16%), and that of the IVF group was the highest (54.9%) .Consequently the development of mouse preimpiantation embryos could be improved when cultured with estrogen and progesterone. The quality of embryos from IVF programs remained comparatively low despite the transfer of apparently healthy embryos.Taken together, these results indicated that an understanding of how in vitro oocyte maturation, in vitro fertilization and embryo culture systems influence both preimpiantation embryo and fetal development should result in systems that consistently produce normal embryos and fetuses.