Figure 1.

The stages of early embryonic development. (a) Six key stages of embryonic development including zygote, 2-cell, 4-cell, 8-cell, morula, and blastocyst stages. Fertilized embryos were cultured to the 8-cell stage (b) and blastocyst stage (d) in normoxic conditions and to the 8-cell stage (c) and blastocyst stage (e) in hypoxic conditions. The images (f,g) were captured with a microscope (LSM 700 META; Zeiss, Jena, Germany). The cleavage rate (j) was not significantly different under hypoxic conditions compared to that of normoxic conditions, but the blastocyst rate (h) and cell count (i) were significantly increased compared to those in the normoxic conditions. Embryonic development data were collected under hypoxic (n = 71) and normoxic (n = 60) conditions. * p < 0.05, ** p < 0.01.