Abstract: 【Objective】 To explore the morphology and developmental potential of embryos derived from single pronucleus (1PN) zygotes in vitro fertilization-embryo transfer

and guide the clinical application. 【Methods】 486 single pronuclear zygotes were observed at 16~18 hours after fertilization and 374 1PN embryos were cultured into blastocysts by the sequential method

recording pronuclear size

polar body

cleavage and blastocyst. 【Results】 A total of 374 1PN embryos were performed blastocyst culture and formed 179 blastocysts (47.86%)

among which 41 were high-quality blastocyst (22.91%). The pronucleus diameter of 374 1PN (27.64 ± 3.30 μm) was greater than 81 1PN embryos which were not cultured (26.22 ± 3.38 μm; P 0.05). The size of pronucleus was statistically significantly larger in 1PN IVF zygotes (27.80 ± 3.44 μm) than in the 1PN ICSI zygotes (26.77 ± 2.29 μm; P 0.05) in the former. No differences were obtained when comparing pronucleus diameters with the different polar body number (uncertain

2PB

1PB) in 1PN embryos (P > 0.05)

but differences were statistically significant in the rates of high-quality blastocyst (39.39%

20.00%

17.65%; P < 0.05). Both of the blastocyst formation (P < 0.05) and high-quality blastocyst (P < 0.05) were statistically significant in embryo quality and the blastomere number. 【Conclusions】 1PN (2PB) embryo from IVF was selected by the morphology and developmental potential

and frozen with high-quality blastocyst which was transferred under the circumstances of unavailable 2PN embryos.