Development of porcine ova that were centrifuged to permit visualization of pronuclei and nuclei.

The obscured pronuclei or nuclei in living one- and two-celled pig ova were revealed after centrifugation for 3 min at 15,000 X g. To determine viability of centrifuged ova, one- and two-celled pig ova were collected from superovulated gilts; half of the ova were centrifuged and all ova were transferred into recipient gilts. Prior to transfer all embryos were stained with tetramethylrhodamine isothiocyanate (TRITC) to distinguish the experimental embryos from the recipients's own ova. Centrifuged ova were transferred into one oviduct of recipient gilts and uncentrifuged ova were deposited into the opposite oviduct. Embryos were recovered 4 days after transfer and were stained with lacmoid or Hoechst 33342 to assess their stage of development. Centrifugation had no detectable influence on survival of the recovered embryos to 4 days. Centrifugation is a simple, reliable method for revealing pronuclei and nuclei of one- and two-celled pig ova and apparently does not alter subsequent preimplantation development.