[The biopsy of preimplantation embryos obtained from donor pigs with follicle-stimulating hormone-induced superovulation].

We have examined possible use of the follicle-stimulating hormone (FSH) for the induction of superovulation in pigs and studied the effect of biopsy of preimplantation pig embryos on their survival in vitro. Superovulation was induced by injecting FSH twice daily over a period of four days for a total dose of 25 units. per animal. Pigs receiving pregnant mare serum gonadotropin (PMSG) according to the standard scheme served as the control. The experiments demonstrated that FSH produces significantly better estrus figures as compared with PMSG (100% and 60%, respectively; p < 0.05). The mean number of ovulations per donor was also better in the FSH group, i.e., 36.5 as compared with 17.3 in the control group (p < 0.05). The mean number of embryos obtained from one donor was higher in FSH treated animals as compared with the animals that received PMSG (29.2 vs. 19.3), however, this difference was not statistically significant. Biopsy of preimplantation pig embryos was conducted by a "manual" technique without a micromanipulator; middle blastocysts collected at days 5-6 after insemination were the most convenient for this operation. Embryos at these developmental stages contained a well developed inner cell mass, which allows separation of trophoectodermal cells only, thus minimizing damage to the embryo. The number of cells in dissected fragments did not depend on the stage of development, and even smallest fragments (4 blastomeres) were sufficient for genome analysis with the aid of PCR. The survival of embryos in vitro after biopsy practically did not differ from that of control intact embryos. Thus, we demonstrated the effective use of FSH for the induction of superovulation in pigs; we also determined the developmental stages which are most convenient for conducting biopsies and developed a technique for preimplantation biopsy, which allows genome analysis of embryos without any decrease of their survival in vitro.