Department of Integrated Applied Life Science, Integrated Graduate School of Medicine, Engineering, and Agricultural Sciences, University of Yamanashi, Kofu, Japan.
Graduate School of Life and Environmental Sciences, Integrated Graduate School of Medicine, Engineering, and Agricultural Sciences, University of Yamanashi Kofu, Japan.
Anim Sci J. 2023 Jan-Dec;94(1):e13907. doi: 10.1111/asj.13907.
In mammals, around fertilization, the nucleolus of embryos transforms into the nucleolus precursor bodies (NPBs), which continue to mature until the blastocyst stage, leading to distinct morphological changes. In our study, we observed two types of nucleolar morphology in mouse in vitro fertilized embryos at the four-cell stage, which we refer to single nucleolus (SN) and multiple nucleoli (MN). To visualize nucleolar morphology, four-cell embryos were immunostained with anti-NOPP140 antibody. These embryos were categorized into five types based on the number of blastomeres carrying SN: SN4/MN0, SN3/MN1, SN2/MN2, SN1/MN3, and SN0/MN4, with percentages of 13, 27, 21, 23 and 9, respectively. Next, using a light microscope, we divided the four-cell in vitro fertilized embryos without fixation into two groups: those with at least two blastomeres displaying SN (SN embryos) and those without (MN embryos). Notably, significantly more SN embryos developed into blastocysts and offspring at 18.5 dpc compared with MN embryos. Furthermore, SN embryos displayed a higher NANOG-positive cell number at the blastocyst stage, significantly lower body and placental weights, resulting in a higher fetal/placental ratio. These findings suggest a close association between nucleolar state at the four-cell stage and subsequent developmental potential.
在哺乳动物中，胚胎的核仁在受精后转化为核仁前体（NPB），这些 NPB 继续成熟，直到囊胚阶段，导致明显的形态变化。在我们的研究中，我们在体外受精的小鼠四细胞胚胎中观察到两种核仁形态，我们称之为单核仁（SN）和多核仁（MN）。为了可视化核仁形态，我们使用抗 NOpp140 抗体对四细胞胚胎进行免疫染色。这些胚胎根据携带 SN 的卵裂球数量分为五类：SN4/MN0、SN3/MN1、SN2/MN2、SN1/MN3 和 SN0/MN4，分别占 13%、27%、21%、23%和 9%。接下来，我们使用光学显微镜将未经固定的体外受精的四细胞胚胎分为两组：至少有两个卵裂球显示 SN（SN 胚胎）和没有 SN 的（MN 胚胎）。值得注意的是，与 MN 胚胎相比，SN 胚胎在 18.5 天时发育成囊胚和后代的比例明显更高。此外，SN 胚胎在囊胚阶段显示出更高的 NANOG 阳性细胞数量，显著更低的体重和胎盘重量，导致更高的胎儿/胎盘比例。这些发现表明，四细胞阶段核仁状态与随后的发育潜力密切相关。
