Division of Child HealthObstetrics and Gynaecology, School of Medicine, University of Nottingham, Nottingham, UK.
Univ LyonUniversité Claude Bernard Lyon 1, Inserm, INRA, Stem Cell and Brain Research Institute U1208, USC1361, 69500 Bron, France.
Reproduction. 2017 Dec;154(6):807-814. doi: 10.1530/REP-17-0514. Epub 2017 Sep 29.
It has been suggested that first embryo cleavage can be related with the embryonic-abembryonic axis at blastocyst stage in mice. Thus, cells of the 2-cell embryo might be already biased to form the inner cell mass or trophectoderm. This study was conducted to observe the possible effects of embryo biopsy on cell allocation patterns during embryo preimplantation in two different mouse strains and the effects of these patterns on further development. First, one blastomere of the 2-cell embryo was injected with a lipophilic tracer and cell allocation patterns were observed at blastocyst stage. Blastocysts were classified into orthogonal, deviant or random pattern. For the first experiment, embryos were biopsied at 8-cell stage and total cell counts (TCC) were annotated. Furthermore, non-biopsied blastocysts were transferred into foster mothers. Then, pups and their organs were weighed two weeks after birth. Random pattern was significantly recurrent (≈60%), against orthogonal (<22%) and deviant (<22%) patterns among groups. These patterns were not affected by biopsy procedure. However, TCC on deviant embryos were reduced after biopsy. Moreover, no differences were found between patterns for implantation rates, litter size, live offspring and organ weights (lungs, liver, pancreas and spleen). However, deviant pups presented heavier hearts and orthogonal pups presented lighter kidneys among the group. In conclusion, these results suggest that single blastomere removal does not disturb cell allocation patterns during pre-implantation. Nonetheless, the results suggest that embryos following different cell allocation patterns present different coping mechanisms against manipulations and further development might be altered.
有人提出，在小鼠中，第一次胚胎分裂可能与囊胚期的胚胎-胚外轴有关。因此，2 细胞胚胎的细胞可能已经偏向于形成内细胞团或滋养外胚层。本研究旨在观察胚胎活检对两种不同品系小鼠胚胎植入前细胞分配模式的可能影响，以及这些模式对进一步发育的影响。首先，将亲脂性示踪剂注射到 2 细胞胚胎的一个卵裂球中，观察囊胚期的细胞分配模式。将囊胚分为正交、偏差或随机模式。在第一个实验中，胚胎在 8 细胞期进行活检，并对总细胞计数（TCC）进行注释。此外，未进行活检的囊胚被转移到代孕母亲体内。然后，在出生后两周称重幼仔及其器官。随机模式（约 60%）明显比正交模式（<22%）和偏差模式（<22%）更频繁出现。这些模式不受活检程序的影响。然而，活检后，偏差胚胎的 TCC 减少。此外，在植入率、产仔数、活产仔数和器官重量（肺、肝、胰腺和脾）方面，模式之间没有差异。然而，偏差幼仔的心脏较重，而正交幼仔的肾脏较轻。总之，这些结果表明，单个卵裂球的去除不会干扰植入前的细胞分配模式。尽管如此，结果表明，遵循不同细胞分配模式的胚胎对操作有不同的应对机制，进一步的发育可能会受到影响。
