Demi-embryos were successfully produced by bisection of ICR mouse embryos at preimplantation stages. They were microsurgically bisected using a microsurgical blade attached to a micromanipulator after pretreatment with 0.5 % pronase in PBS for two minutes or not. Embryos with softened zona pellucida were more easily bisected and less damaged than intact embryos. The highest success rate in bisection has been achieved by selecting blastocysts (94.1 % in success rate with intact blastocysts and 100 % in success rate with zona softened blastocysts). Demi-embryos without zona pellucida were cultured in D-PBS or M-16 medium at 37deg C, 5 % CO2 in air for 72 hours for 2-cell stage embryos, 48 hours for 4-to 8-cell stage embryos, 24 hours for morula stage embryos and 6-12 hours for blastocyst stage embryos. For the in vitro culture of 2-cell stage embryos, 100 micro M 2Na-EDTA was added to the media. M-16 medium was better for the in vitro development of mouse embryos than PBS, and PBS is not considered to be suitable for long-term culture of embryos, especially at early stage of cleavage. In M-16 medium, developing rate of demi-embryos of which pair underwent development to form eublastocysts was 15.8 % at 2-cell stage, 16.8 % at 4-cell stage, 38 % at 8-cell stage, 89.6 % at morula stage and 94.4 % at blastocyst stage, respectively. The more rapid and efficient production of demi-embryos and higher viability after bisection can be expected by softening zona pellucida with pronase and by selecting morulae or blastocysts rather than embryos at early stage of cleavage.

Study of the regeneration processes and raising the efficiency of rape (Brassica napus) organs and tissues cultivation in vitro methods, as well as the achievement of a stable yield of proper regenerants were realized in the conditions of the Republic of Belarus. The obtained data specified the possibility of generation of rape finished regenerants in vitro culture without additional passages and transfers by means of effectively selected concentrations of phytohormones and biologically active substances, which made it possible to realize principles of totipotency and polarity of crop vegetative organs. On the explant part which was submerged into culture medium there was formed a root, and on opposite one - the morphogen structures. The possibility of obtaining rape regenerants from hypocotyls segments by straight regeneration was studied. Application of the analyzed substances considerably simplified and reduced the price of process of full regenerants formation, and made it possible to receive a wide spectrum of various forms that was important for selection process due to the opportunity to select valuable (in protein content) samples for the further studies and their inclusion into production process