Abstract. The present study was carried out to examine the activation and parthenogenetic development of pig oocytes after exposure to ultrasound in sorbitol media supplemented with different concentrations of Ca 2+ . The activation rates (68.8-75.6%) of oocytes exposed to ultrasound in media containing 0.1-1.0 mM Ca 2+ were significantly (P<0.05) higher than those (54.3-58.3%) of oocytes exposed to ultrasound in media containing 0-0.05 mM Ca 2+ . When oocytes were exposed to ultrasound in media containing 0.1-0.5 mM Ca 2+ , the blastocyst formation rates (20.5-21.3%) were significantly (P<0.05) higher than those (3.3-6.0%) of oocytes exposed to ultrasound in media containing 0, 0.05 or 1.0 mM Ca 2+ . The results of the present study showed that the concentration of Ca 2+ in the medium used for exposure to ultrasound affects the activation and parthenogenetic development of pig oocytes and showed that the optimal Ca 2+ concentration is 0.1-0.5 mM. Key words: Activation, Ca 2+ , Parthenogenetic development, Pig, Ultrasound (J. Reprod. Dev. 54: [42][43][44][45] 2008) uccessful development of cloned embryos produced using nuclear transfer depends on artificial stimulation-induced activation [1]. Electric pulses are the most common method of activation of embryos in somatic cell nuclear transfer studies that have succeeded in producing cloned piglets [2][3][4][5][6][7][8][9][10][11]. Recently, we have shown that ultrasound can induce nuclear activation and parthenogenetic development of pig oocytes matured in vitro [12]. Ultrasound is also useful for inducing activation and in vitro development of cloned embryos derived from miniature pig somatic cells [13]. The blastocyst formation rates of pig oocytes and miniature pig cloned embryos activated by ultrasound are not significantly different from those of oocytes and embryos activated by electric pulses [12,13]. In addition, miniature pig cloned embryos activated by ultrasound have the ability to develop into piglets after transfer to recipient females [14]. The advantage of the activation protocol using ultrasound is that it can treat more oocytes and embryos at one time compared with the activation protocol using electric pulses [12]. This advantage is valuable in somatic cell nuclear transfer studies requiring activation of a lot of cloned embryos. Moreover, ultrasound is considered to be better artificial stimulation for activation of embryos than electric pulses in production of cloned miniature pigs because no piglets have been obtained from embryos activated by electric pulses [14]. Therefore, it would be useful to clarify the factors affecting the activation status and parthenogenetic development of pig oocytes exposed to ultrasound and optimize the activation protocol.Oocyte activation by electric pulses is initiated by an elevation of intracellular Ca 2+ . A transient increase in intracellular Ca 2+ is triggered by an influx of extracellular Ca 2+ immediately after electric stimulation [15]. When pig oocytes are activated by electric stimulation, the c...
Purpose To report successful pregnancies after the transfer of re-vitrified human day 7 blastocysts developed from vitrified cleaved embryos. Methods and results A total of five day 7 blastocysts developed from vitrified cleaved embryos were re-vitrified and re-warmed. All of five re-vitrified day 7 blastocysts (100%) survived after warming and were transferred to three patients. Two of the women became clinically pregnant. Of these women, one woman delivered a healthy baby and the other pregnancy is ongoing at 26 weeks of gestation. Conclusions This is the first report of successful pregnancies after the transfer of re-vitrified human day 7 blastocysts developed from vitrified cleaved embryos.
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