title: Effects of oocyte collection time and injection position on pronucleus formation and blastocyst development in round spermatid injection in mouse.
abstract: The injection of spermatozoa into mouse, human and rabbit oocytes at specific times and positions can result in different rates of viable embryo development. However, it is not clear how the timing and position of round spermatid injection (ROSI) affect pronucleus (PN) formation and blastocyst development of mice. First, we determined the changes in relative position of the first polar body and the spindle, carried out ROSI from 11.5 to 13 h post-hCG administration, then activated by Sr2+, and finally compared the development of ROSI zygotes, including the formation of pronuclei and development of blastocyst. Between 11.5 and 13 h post-hCG administration, the rate of 2PN formation by ROSI at 3 o'clock was the highest among all treated oocytes. Moreover, the blastocyst rate of zygotes with two pronuclei (2PN) was up to 27.41%. These results suggest that the time and position of ROSI can significantly influence the formation of 2PN, that the rates of 2PN formation are closely correlated with blastocyst formation and that the formation of 2PN is necessary for later embryo development.
authors.affiliation: State Key Laboratory of Reproductive Biology, Institute of Zoology and Graduate School, Chinese Academy of Sciences, Beijing, People's Republic of China.
authors.forename: Man-Xi
authors.initials: MX
authors.lastname: Jiang
authors.forename: Yue-Liang
authors.initials: YL
authors.lastname: Zheng
authors.forename: Shu-Zhen
authors.initials: SZ
authors.lastname: Liu
authors.forename: Cai-Xia
authors.initials: CX
authors.lastname: Yang
authors.forename: Li-Sheng
authors.initials: LS
authors.lastname: Zhang
authors.forename: Ying-Chun
authors.initials: YC
authors.lastname: Ouyang
authors.forename: Qing-Yuan
authors.initials: QY
authors.lastname: Sun
authors.forename: Da-Yuan
authors.initials: DY
authors.lastname: Chen
mesh_terms: D000818:Animals; D001755:Blastocyst / Q000502:physiology*; D004624:Embryo Transfer; D047108:Embryonic Development; D005260:Female; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D008815:Mice, Inbred Strains; D008845:Microinjections; D009865:Oocytes / Q000502:physiology*; D020554:Sperm Injections, Intracytoplasmic / Q000379:methods*; D013087:Spermatids; D013997:Time Factors; D015053:Zygote / Q000254:growth & development*