Effect of oocyte quality on blastocyst development after in vitro fertilization (IVF) and intracytoplasmic sperm injection (ICSI) in a sheep model

Abstract

Objective: To compare blastocyst production, after IVF and ICSI, from sheep oocytes of various quality. Sham-injected oocytes and parthenogenetic activated oocyte groups were considered as control.

Design: Prospective experimental study.

Setting: University.

Animal(s): Three- to 6-month-old sheep.

Intervention(s): Oocyte quality was assessed with the use of brilliant cresyl blue (BCB) stain. Adenosine triphosphate content was measured. Intracytoplasmic sperm injection and IVF were performed and blastocyst development and cell numbers were analyzed.

Main outcome measure(s): Adenosine triphosphate content, embryo development and blastomere numbers.

Result(s): After IVF, BCB-stained (BCB+) oocytes developed up to the blastocyst stage at higher percentages and with more cells per embryo (24.1% vs 4.0% and 69.7 vs 43.9, respectively) than unstained (BCB-) oocytes. Using intracytoplasmic sperm injection, no differences were found in blastocyst production (14.3% vs 11.8%) and number of cells per embryo (71.1 vs 54.3) between BCB+ and BCB- oocytes. Adenosine triphosphate content was higher before in vitro maturation than after in both types of oocytes. Brilliant cresyl blue-stained oocytes had more adenosine triphosphate content than BCB- oocytes.

Conclusion(s): Brilliant cresyl blue-stained oocytes show more adenosine triphosphate content than BCB- oocytes. Results from IVF were affected by the oocyte quality while ICSI did not produce differences in embryo development or blastomere numbers.