Agca Y, Monson R L, Northey D L, Mazni O A, Schaefer D M, Rutledge J J
Department of Animal Sciences, University of Wisconsin-Madison 53706, USA.
Theriogenology. 1998 Jul 1;50(1):147-62. doi: 10.1016/s0093-691x(98)00121-6.
In vitro and in vivo developmental competence of fresh and cryopreserved in vitro produced (IVP) bovine embryos was evaluated up to birth. Three experiments were done. The objective in the first experiment was to develop an optimal vitrification procedure for IVP bovine embryos by determining effects of exposure time (2, 5, 10, 20 min) and temperature (4, 22, 27 degrees C) in cryoprotective agents prior to vitrification on their post-thaw viability. The best combination was used in Experiments 2 and 3. In the second experiment, the importance of post-thaw morphologic selection on pregnancy rates was determined by transferring either selected or unselected single embryos. In the third experiment, pregnancy initiation, maintenance and calving results of vitrified embryos were compared with fresh and conventionally frozen embryos. Fetal losses, birth weights, gestation lengths and frequency of dystocia in the third experiment were monitored. The interaction of exposure time and temperature on both post-thaw re-expansion and hatching rates was significant (P < 0.01). Five minute exposure at 27 degrees C was optimal. In the second experiment, post-thaw selected vitrified embryos had higher pregnancy rates than unselected embryos (P < 0.05). In the third experiment, the pregnancy rate of vitrified embryos did not differ from that of fresh embryos (P > 0.05). However, pregnancy rate of conventionally frozen embryos was lower than that of fresh or vitrified embryos (P < 0.05). Of 92 calves born, 53 were male and 39 were female. Birth weights and dystocia scores of single-born calves did not differ between sexes (P > 0.05). Twin-born calves were lighter than single-born calves (P < 0.05). Overall, the data demonstrate that the transfer of vitrified IVP bovine embryos can result in healthy, apparently normal calves similar to those derived from transfer of fresh and conventionally frozen IVP bovine embryos.
对新鲜的和冷冻保存的体外生产（IVP）牛胚胎的体外和体内发育能力进行了直至出生的评估。进行了三个实验。第一个实验的目的是通过确定玻璃化前在冷冻保护剂中的暴露时间（2、5、10、20分钟）和温度（4、22、27摄氏度）对解冻后活力的影响，来开发一种针对IVP牛胚胎的最佳玻璃化程序。最佳组合用于实验2和实验3。在第二个实验中，通过移植经过挑选或未经挑选的单个胚胎，确定解冻后形态学选择对妊娠率的重要性。在第三个实验中，将玻璃化胚胎的妊娠起始、维持和产犊结果与新鲜胚胎和传统冷冻胚胎进行了比较。监测了第三个实验中的胎儿损失、出生体重、妊娠期长度和难产频率。暴露时间和温度对解冻后再扩张率和孵化率的相互作用具有显著意义（P<0.01）。在27摄氏度下暴露5分钟是最佳的。在第二个实验中，解冻后经过挑选的玻璃化胚胎的妊娠率高于未经挑选的胚胎（P<0.05）。在第三个实验中，玻璃化胚胎的妊娠率与新鲜胚胎的妊娠率没有差异（P>0.05）。然而，传统冷冻胚胎的妊娠率低于新鲜胚胎或玻璃化胚胎（P<0.05）。在出生的92头犊牛中，53头为雄性，39头为雌性。单胎出生犊牛的出生体重和难产评分在性别之间没有差异（P>0.05）。双胎出生的犊牛比单胎出生的犊牛轻（P<0.05）。总体而言，数据表明，移植玻璃化的IVP牛胚胎可产生健康、外观正常的犊牛，类似于新鲜的和传统冷冻的IVP牛胚胎移植所产生的犊牛。
