Development of parthenogenetic rat embryos.

In an effort to establish cloning technology for the rat, we tested several methods (electric stimulation, treatment with ethanol or strontium) for the parthenogenetic activation of rat oocytes. We observed marked individual differences among rats of the outbred Wistar strain in their ability to yield activatable oocytes. These differences were independent of the activation protocol and may be due to a genetic predisposition that is crucial for the parthenogenetic activation of oocytes.

[Investigation of the effect of various buffer solutions used for microinjection of gene-engineering constructs on preimplantation development of mouse embryos].

We studied the effects of some buffer solutions used for microinjection in mammalian zygotes on preimplantation development of (CBA x C57BL)F1 mouse embryos in vitro. The rate of embryo survival was estimated according to their capacity to develop to the stages of blastocyst and blastocyst hatched from zona pellucida. The results obtained suggested a reduced rate of survival of zygotes to the blastocyst stage after the injection into a pronucleus of the buffers Tris-HCl with EDTA, Tris-HCl with MgCl2 and NaCl, and medium M2 (p < 0.

[In vitro development of murine embryos using different types of microinjections].

We studied the effects of different types of microinjections, such as the mechanical damage to cytoplasmic and nuclear membranes of the zygote and the injection of various gene-engineering constructs or buffer solutions into the cytoplasm or the pronucleus, on the preimplantation of murine embryos (CBA x x C57BL)F1. The survival rate of the embryos was estimated by their capacity to develop in vitro to the blastocyst or hatched blastocyst stages. Puncture of the cytoplasm using a microneedle and injection of buff or foreign DNA did not affect the zygotes capacity for further in vitro development.

[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.

[The preservation of mammalian ova and embryos at positive near-zero temperatures. II. The general patterns and mechanisms of hypothermic exposure].

General patterns of the sensitivity of embryos to hypothermia are described, such as its species-specific dependence, its relationship with the embryonic stage, etc. Data are provided on differences in the cold resistance of the inner cell mass and trophectoderm cells, as well as that of the nucleus and cytoplasm. The mechanisms underlying the effects of cold on mammalian eggs and embryos are considered, and ways of improving the method of hypothermic storage are discussed.