Embryotropic role of hemoglobin and ethylenediaminetetraacetic acid in preimplantation development of ICR mouse 1-cell embryos

Objective: To evaluate embryotropic action of (EDTA) on preimplantation emb ryo development. Design: In vitro model study using mouse embryos. Setting: University affiliated hospital, Pochon CHA University. Animals: Four-week-old block strain ICR mice naturally mated after superovu lation. Intervention(s): One-cell embryos were cultured in serum-free, modified pre implantation-l medium, to which 1 mug/ml Hb and/or 0.1 mM EDTA were added. Main Outcome Measure(s): Preimplantation development and blastomere number. Result(s): More (P<.05) 1-cell embryos developed to the 4-cell (52% vs. 67% -84%), 8-cell (48% vs. 65%-81%), and blastocyst (40% vs. 61%-79%) stages af ter the addition of hemoglobin (Hb) and/or EDTA than after no addition. Hig hest proportion of embryos developed to each stage after the combined addit ion of Hb + EDTA. EDTA specifically stimulated the development before the 8 -cell stage, which was as similar as Hb + EDTA. On the contrary, higher rat io of morula to blastocyst transformation was obtained after the addition o f Hb or Hb + EDTA than after no addition (0.76 vs. 0.96-0.98). Significant increases in the cell number of blastocysts (46.5-47.2 vs. 53.2 cells), inn er cell mass (ICM) cells (16.7-17.5 vs. 21 cells), and the ratio of ICM cel ls to trophoblasts (0.3-0.37 to 0.39) were found after the combined additio n of Hb + EDTA, compared with no addition or with the addition of EDTA or I -Ib alone. Conclusions: Hb and EDTA have stage-specific effects on supporting preimpla ntation embryo development: Hb promotes both the development before the 8-c ell stage and the morula to blastocyst transformation, whereas EDTA mainly promotes the development to the 8-cell stage. The combined exposure of embr yos to Hb and EDTA improves not only preimplantation development but also t he growth and quality of blastocysts. (C) 2000 by American Society for Repr oductive Medicine.