Micromanipulation of day-6 porcine embryos to produce split-embryo piglets

Microsurgical bisection of porcine morulae and blastocysts to produce monozygotic twin pregnancy

“…The advantage of using postmorula-stage embryos for bisection is that the divided embryos no longer require protection from the zona pellucidae in vivo [Polge, 19851. It has been shown that the half-embryos obtained from morulae and blastocysts, as well as those produced from early cleavage-stage embryos, can develop into normal conceptuses in mice [Moustafa and Hahn, 1978;Tsunoda and McLaren, 1983;Nagashima et al, 19841, sheep [Willadsen, 1979, 1981Gatica et al, 1984;Willadsen and Godke, 19841, cows [Willadsen and Polge, 1981;Williams et al, 1982;Ozil et al, 19821, and goats [Tsunoda et al, 1984, 198.51. This is also true for porcine halfembryos [Willadsen, 1982;Rorie et al, 1985;Nagashima et al, 1987;Ash et al, 19881. The present study clearly demonstrates that porcine monozygotic twin fetuses can be obtained from bisected blastocysts.…”

“…The artificial production of monozygotic twins by transplantation of microsurgically bisected embryos has recently been studied in domestic animals, including sheep [ Willadsen, 1979[ Willadsen, , 1980Gatica et al, 1984;Godke, 19841, goats [Tsunoda et al, 1984,19851, cows [Willadsen andPolge, 1981;Ozil et al, 1982;Williams et al, 1984;Ozil, 1983;Lambeth et al, 19831, horses [Allen and Pashen, 19841, and pigs [Willadsen, 1982;Rorie et al, 1985;Nagashima et al, 19881. At present, however, information on the developmental ability of porcine bisected embryos has not been as extensively reported as that of cow and sheep halfembryos. Our study was carried out to examine the developmental ability of the porcine half-embryos produced from morulae and blastocysts by four treatments of micromanipulation.…”

Effect of cell‐free synchronous uterine flushings and microsurgery on the development of porcine embryos in vitro

“…This study demonstrates that exposure of 4-cell embryos with incised zonae pellucidae to cell-free synchronous uterine flushings is not detrimental to porcine embryo development in vitro. The ability of porcine demi-morulae and blastocysts, without a zona pellucida, to develop to term following their transfer to synchronized recipients also indicates that a synchronous uterine environment has no deleterious effect on the in vivo development of porcine embryos which lack an intact zona pellucida (Rorie et al, 1985;Nagashima et al, 1987). Thus it is unlikely that d 3 porcine cell-free synchronous uterine flushings contain a n embryotoxic factor(s) that is normally screened by the intact zona pellucida.…”

In vitro technologies related to pig embryo transfer

“…Research and initial application in the field of gene manipulation to improve growth and disease resistance, to generate foreign proteins in blood and milk, and to create tissues and organs for xenotransplantation need embryo transfer [7,18,19,35,71,95]. Other reproductive techniques to produce offspring like ovum pick up, and in vitro maturation and fertilization [14,64,68,87,110,113], generation of sexed embryos [88,89], cryoconservation of embryos [26, 41,46] and cloning [12,69,80,94] require also successful handling of embryo transfer technique. However, these reproductive techniques did not find practical application in swine production, yet.…”

“…In the pig these methods are rare applied. Piglets were obtained after transfer of bisected blastocysts [69,92,94]. Pregnancy rates up to 82% are possible [92], however, the survival rate of demi-embryos is reduced and range between 17% and 34% [12, 69,92] compared to 52% after transfer of complete control embryos [12].…”