Light exposure of oocytes and pregnancy rates after their transfer in the rabbit

Groups of unfertilized and pronuclear stage rabbit oocytes were exposed to fluorescent light of 3250 lx for 20-30 min at 37 degrees C. In 6 experiments with fertilization achieved in vivo, 54% of the zygotes exposed as secondary oocytes and 67% of light-protected controls had implanted and developed normally 16 days after transfer to the contralateral oviducts of synchronized recipients. When pronuclear oocytes were exposed similarly in 8 experiments, 63% had established a normal pregnancy at 16 days after transfer compared to 65% of the controls. In 5 of these pregnancies which were allowed to proceed to term, all the young born appeared normal. Though similar in size, it is not clear whether the rabbit oocyte constitutes a suitable model for the human oocyte in regard to the effects of visible light. However, the level of exposure used here is 200-300 times that experienced during normal in-vitro manipulation of human eggs. The absence of significant effects should allay concerns that light is a negative factor in the normal procedure of in-vitro fertilization in man.