Careful selection of the host embryo is critical to the efficient production of knockout (KO) mice when injecting mouse embryonic stem (mES) cells into blastocysts. B6(Cg)-Tyr^c−2j/J (B6 albino) and C57BL/6NTac (B6NTac) strains of mice are widely used to produce host blastocysts for such procedures. Here, we tested these two strains to identify an appropriate match for modified agouti C57BL/6N (JM8A3.N1) mES cells. When comparing blastocyst yield, super-ovulated B6NTac mice produced more injectable blastocysts per female than B6 albino mice (8.2 vs. 5.4). There was no significant difference in birth rate when injected embryos were transferred to the same pseudopregnant recipient strain. However, the live birth rate was significantly higher for B6NTac blastocysts than B6 albino blastocysts (62.7% vs. 50.2%). In addition, the proportion of pups exhibiting high-level and complete chimerism, as identified by coat color, was also significantly higher in the B6NTac strain. There was no obvious difference in the efficiency of germline transmission (GLT) when compared between B6NTac and B6 albino host embryos (61.5% vs. 63.3% for mES clones; 64.5% vs. 67.9% for genes, respectively), thus suggesting that an equivalent GLT rate could be obtained with only a few blastocyst injections for B6NTac embryos. In conclusion, our data indicate that B6NTac blastocysts are a better choice for the microinjection of JM8A3.N1 mES cells than B6 albino blastocysts.

将小鼠胚胎干 (mES) 细胞注入囊胚时，仔细选择宿主胚胎对于高效生产敲除 (KO) 小鼠至关重要。B6(Cg)-Tyr ^c-2j /J（B6 白化病）和 C57BL/6NTac (B6NTac) 小鼠品系被广泛用于生产用于此类程序的宿主囊胚。在这里，我们测试了这两种菌株，以确定与改良的刺豚鼠 C57BL/6N (JM8A3.N1) mES 细胞的适当匹配。在比较囊胚产量时，与 B6 白化小鼠相比，超排卵 B6NTac 小鼠每只雌性产生更多的可注射囊胚（8.2 vs.5.4)。当注射胚胎被转移到相同的假孕受体菌株时，出生率没有显着差异。然而，B6NTac 囊胚的活产率明显高于 B6 白化囊胚（62.7%与50.2%）。此外，B6NTac 菌株中表现出高度和完全嵌合体的幼崽比例（通过毛色确定）也显着更高。与 B6NTac 和 B6 白化宿主胚胎相比，种系传递 (GLT) 的效率没有明显差异（mES 克隆为61.5%对63.3%；64.5%对分别为基因的 67.9%），因此表明只需为 B6NTac 胚胎注射几次囊胚即可获得等效的 GLT 率。总之，我们的数据表明，与 B6 白化囊胚相比，B6NTac 囊胚是 JM8A3.N1 mES 细胞显微注射的更好选择。