Visualization of meiotic spindle and subsequent embryonic development in in vitro and in vivo matured human oocytes.

Purpose: The aim of this study is to investigate the relationship between spindle location and embryonic development of in vivo and in vitro matured human oocytes.

Methods: The spindles of 134 in vivo matured, 105 in vitro matured oocytes were examined by Polscope at the time of ICSI.

Results: The spindles were visualized in 83.6 and 77.1% of in vivo and in vitro matured oocytes respectively. The rate of fertilization of in vivo matured oocytes with spindles beneath or adjacent to the first polar body (angle of 0-5 degrees) was significantly higher (93.3%) than all other groups. The proportions of various spindle positions did not differ statistically in in vivo and in vitro matured oocytes.

Conclusions: Meiotic spindle location with regard to the first polar body appears to influence fertilization rate.