Miyoshi Kazuchika, Inoue Sumiko, Himaki Takehiro, Mikawa Satoshi, Yoshida Mitsutoshi
Laboratory of Animal Reproduction, Faculty of Agriculture, Kagoshima University, Kagoshima, Japan.
Mol Reprod Dev. 2007 Dec;74(12):1568-74. doi: 10.1002/mrd.20730.
The present study was carried out to determine (1) the optimal duty cycle of ultrasound for activation of pig oocytes and cloned embryos derived from miniature pig fetal fibroblasts and (2) whether cloned embryos can develop to term following activation by ultrasound stimulation. When oocytes were exposed to ultrasound with 20% or 30% duty cycle, the blastocyst formation rates were significantly (P < 0.05) higher than that of oocytes exposed to ultrasound with 10% duty cycle. In contrast, the blastocyst formation rate of cloned embryos decreased as the duty cycle of ultrasound increased; the value of embryos exposed to ultrasound with 10% duty cycle was significantly (P < 0.05) higher than that of embryos exposed to ultrasound with 50% duty cycle. When cloned embryos exposed to ultrasound with 10% duty cycle were transferred into the oviducts of two recipient gilts to assess their development in vivo, the pregnancy of one of the gilts was maintained to term and two piglets were delivered via Cesarean section. The results of the present study showed that (1) although the duty cycle of ultrasound affects in vitro development after activation of both pig oocytes and miniature pig cloned embryos, the optimal duty cycle is different between them and (2) miniature pig cloned embryos have the ability to develop into piglets after activation by ultrasound stimulation.
（1）激活猪卵母细胞及源自小型猪胎儿成纤维细胞的克隆胚胎的超声最佳占空比；（2）经超声刺激激活后克隆胚胎能否发育至足月。当卵母细胞暴露于占空比为20%或30%的超声时，囊胚形成率显著高于（P<0.05）暴露于占空比为10%超声的卵母细胞。相反，克隆胚胎的囊胚形成率随超声占空比增加而降低；暴露于占空比为10%超声的胚胎的值显著高于（P<0.05）暴露于占空比为50%超声的胚胎。当将暴露于占空比为10%超声的克隆胚胎移植到两头受体母猪的输卵管中以评估其体内发育情况时，其中一头母猪维持妊娠至足月，并通过剖宫产分娩出两头仔猪。本研究结果表明：（1）尽管超声占空比影响猪卵母细胞和小型猪克隆胚胎激活后的体外发育，但两者的最佳占空比不同；（2）小型猪克隆胚胎经超声刺激激活后有能力发育成仔猪。
