Differences in resistance against osmotic challenge among C57BL/6, DBA/2 and their hybrid mice metaphase II (MII) stage oocytes.

Oocytes of B6D2F1 (BDF1) mice are often used as recipients for intracytoplasmic sperm injection because of their cell membrane resistance against capillary penetration. It is assumed that oocytes of BDF1 mice have superior traits because of their hybrid vigour. However, the mechanisms of hybrid vigour are unclear.

Potassium bromate disrupts mitochondrial distribution within murine oocytes during in vitro maturation.

Purpose: As disturbed mitochondrial distribution is thought to be a cause of the aging of oocytes, it was investigated whether oxidizing agents exert harmful effects on nuclear maturation and mitochondrial cluster formation in murine oocytes and whether antioxidants could rescue such harmful effects in vitro.

Methods: Oocytes were obtained from female Institute of Cancer Research mice 48 h after an intraperitoneal injection of 7.5 IU pregnant mare serum gonadotropin.