DEVELOPMENT OF RABBIT ZYGOTES CULTURED IN PROTEIN-FREE MEDIUM WITH CATALASE, TAURINE, OR SUPEROXIDE-DISMUTASE

The present study was designed to examine the influence of several pot ential antioxidants in a synthetic medium completely devoid of macromo lecules. Antioxidants may be beneficial as additives to a synthetic me dium because they could serve as scavengers of toxic free radicals in media lacking serum, serum albumin, or other macromolecules that may s erve as scavengers in more complex media. Rabbit zygotes were cultured for 72 h at 39-degrees-C in media containing varying concentrations o f the antioxidants in a gas phase consisting of 5% CO2:95% humidified air. At 7 h embryo development was recorded, and embryos were fixed an d stained with Hoechst 33342 DNA stain to facilitate counting of cells . In experiment 1, concentrations of catalase ranging from 2 50 to 100 0 IU did not affect the proportion of zygotes developing into blastocy sts or the cell number (p > 0.05). In experiment 2, 2.5-10 mM taurine increased the proportion of zygotes developing into expanding blastocy sts (70-78% vs. 40% for controls) and increased cell number from 100 t o 154-159 (p < 0.05). In experiments 3 and 4, superoxide dismutase was tested over a range of 100-2400 IU/ml. The response reached a plateau at 600 IU/ml, with positive responses in rate of embryo development a nd growth similar to that found with taurine in experiment 2. These st udies indicate that culture of zygotes into blastocysts in a macromole cule-free medium with 5% CO,:95% air is substantially improved when ag ents that could serve as antioxidants are included. Other mechanisms o f action are not excluded by these studies.