[Effect of cryopreservation on the morphology of blastocysts of the ferret Mustela eversmanni].

In this study, we have undertaken an attempt to use the technique of cryopreservation of a mustelid embryo-sing Mustela eversmanni as the experimental model. Ferret blastocysts were frozen with glycerol or DMSO. Characteristic feature of blastocyst morphology, as well as changes in their ultrastructure after freezing and cryopreservation have been examined by techniques of light and electron microscopy.

[The interaction of homotypic and heterotypic embryonic stem cells with developing embryos].

It has been demonstrated that embryonic stem cells form adhesive contacts with external blastomeres of mouse morula, while there is no such contact with blastocysts. The development of morula in the blastocysts is delayed inside a dense layer of such cells; however, in some cases, external blastomeres of the morula begin to differentiate into trophoblastic cells. The introduction of an excessive number of embryonic stem cells (15-20) into a 4-8-cell embryo results in abnormal development.

[Effect of cryopreservation on the morphology of preimplantation embryos of the ISIAH rat line].

Micronuclei of preimplantation embryos of the hypertensive rat strain with inherited spontaneously induced arterial hypertension (ISIAH) are studied. Also studied are the formation of micronuclei and other morphological changes in these embryos after freezing, cryoconservation, and consequent transplantation to Wistar recipient rats. Analysis of semithin sections demonstrates that the above procedures lead to the formation of micronuclei in most embryos, while the shape of nuclei changes in only some embryos.

[Superovulation induced by the administration of PMSG to mustelids].

In this paper, we have attempted to use the technique of superovulation in mustelids. Ermine (Mustela erminea) and several species of ferret (Mustela eversmanni, Mustela putorius, Mustela putorius furo [correction of hamster (Putorius eversmanni, Putorius putorius, Putorius putorius furo)] have been used as experimental models. We have conducted a detailed study of superovulation and early embryonic development in animals of these species treated with PMSG [correction of GPMS].

[The visualization of the pronuclei in zygotes of the American mink].

Visualization of the pronuclei in optically nontransparent mink zygotes was achieved after centrifugation at 15,000 g. Under these conditions, the lipid fraction was concentrated in the light hemisphere of the zygote, while the pronuclei were localized in the equatorial area. Centrifugation did not affect the viability of zygotes, and no reliable differences in the rate of birth were found after transplantation of the native and centrifuge zygotes to the recipient females.