Effect of cytochalasin B pre-treatment of in vitro matured porcine oocytes before vitrification.

The study tested the efficacy of pre-treating mature porcine oocytes with cytochalasin B before vitrification by the open pulled straw method (OPS) in a low toxicity solution containing ice blockers. The effects of pre-treating the oocytes with 7.5 micrograms per ml cytochalasin B before vitrification on membrane integrity, chromosome organisation and cortical granule distribution were evaluated. When oocytes pre-treated with cytochalasin B before vitrification were compared with control oocytes, similar membrane integrity was observed. In contrast, when both vitrified oocytes groups (treated and untreated with cytochalasin B) were compared with fresh oocytes, significantly lower proportions of oocytes with normal chromosomes aligned regularly on the metaphase plate and peripheral cortical granule distribution were observed. The percentages of oocytes with normal chromosomes aligned regularly on the metaphase plate were similar between those treated or untreated with cytochalasin B before vitrification. Similar results were found for normal cortical granules distribution. Irrespective of previous cytochalasin B exposure, vitrification gave rise to higher abnormal cortical granule distribution percentages. Cytochalasin B pretreatment of oocytes before vitrification does not help to reduce the damage induced by the cryopreservation process of porcine oocytes.