Short-Term Exposure of Two-Cell Hamster Embryos to Collection Media is Detrimental to Viability

Hamster 2-cell embryos were transferred to recipients to provide information on the block to development in vitro. Previous attempts to elucidate this block have focused on possible deficiencies in the culture medium. In this study the possibility was examined that the media used for embryo collection are actually embryotoxic. Two-cell embryos obtained from superovulated mated hamsters were exposed to collection media [either a Hepes-buffered modified Tyrode's solution (TALP-Hepes) or PB1] during either a "fast transfer" procedure (time elapsed from collection to transfer 3.9 +/- 0.7 min or 3.7 +/- 0.9 min, respectively) or a "slow transfer" procedure (time elapsed 19.1 +/- 4.4 min or 20.8 +/- 5.7 min, respectively). In each transfer experiment, equal numbers of embryos from the same donor pool were transferred to one oviduct (fast transfer) and to the contralateral oviduct (slow transfer) of the same recipient. Embryos were recovered 33-36 h after transfer; embryos developing at least to the 8-cell stage were considered viable. Significant differences were found (P less than 0.005) between the viability of embryos subjected to fast and slow transfer procedures using either TALP-Hepes (embryo survival 60.8% vs. 22.2%, respectively, difference 38.6%) or PB1 (survival 50.6% vs. 10.5%, respectively, difference 40.1%). These data show that length of exposure to collection media is an important variable in determining subsequent developmental ability of 2-cell hamster embryos.(ABSTRACT TRUNCATED AT 250 WORDS)