PDF(Pubmed)
Abstract：
In vitro production (IVP) of equine embryos is increasingly popular in clinical practice but suffers from higher incidences of early embryonic loss and monozygotic twin development than transfer of in vivo derived (IVD) embryos. Early embryo development is classically characterized by two cell fate decisions: (1) first, trophectoderm (TE) cells differentiate from inner cell mass (ICM); (2) second, the ICM segregates into epiblast (EPI) and primitive endoderm (PE). This study examined the influence of embryo type (IVD versus IVP), developmental stage or speed, and culture environment (in vitro versus in vivo) on the expression of the cell lineage markers, CDX-2 (TE), SOX-2 (EPI) and GATA-6 (PE). The numbers and distribution of cells expressing the three lineage markers were evaluated in day 7 IVD early blastocysts (n = 3) and blastocysts (n = 3), and in IVP embryos first identified as blastocysts after 7 (fast development, n = 5) or 9 (slow development, n = 9) days. Furthermore, day 7 IVP blastocysts were examined after additional culture for 2 days either in vitro (n = 5) or in vivo (after transfer into recipient mares, n = 3). In IVD early blastocysts, SOX-2 positive cells were encircled by GATA-6 positive cells in the ICM, with SOX-2 co-expression in some presumed PE cells. In IVD blastocysts, SOX-2 expression was exclusive to the compacted presumptive EPI, while GATA-6 and CDX-2 expression were consistent with PE and TE specification, respectively. In IVP blastocysts, SOX-2 and GATA-6 positive cells were intermingled and relatively dispersed, and co-expression of SOX-2 or GATA-6 was evident in some CDX-2 positive TE cells. IVP blastocysts had lower TE and total cell numbers than IVD blastocysts and displayed larger mean inter-EPI cell distances; these features were more pronounced in slower-developing IVP blastocysts. Transferring IVP blastocysts into recipient mares led to the compaction of SOX-2 positive cells into a presumptive EPI, whereas extended in vitro culture did not. In conclusion, IVP equine embryos have a poorly compacted ICM with intermingled EPI and PE cells; features accentuated in slowly developing embryos but remedied by transfer to a recipient mare.
摘要：
马胚胎的体外生产（IVP）在临床实践中越来越受欢迎，但与体内衍生（IVD）胚胎的转移相比，早期胚胎丢失和单卵双胞胎发育的发生率更高。早期胚胎发育的经典特征是两个细胞命运决定：（1）首先，滋养外胚层（TE）细胞从内细胞团（ICM）分化；（2）第二，ICM分为外胚层(EPI)和原始内胚层(PE)。这项研究检查了胚胎类型（IVD与IVP）的影响，发育阶段或速度，和培养环境（体外与体内）对细胞谱系标记表达的影响，CDX-2(TE),SOX-2（EPI）和GATA-6（PE）。在第7天IVD早期胚泡（n=3）和胚泡（n=3）中评估表达三个谱系标记的细胞的数量和分布。在IVP胚胎中，7岁后首次被鉴定为胚泡(快速发育，n=5)或9(缓慢发展，n=9）天。此外，第7天，在体外（n=5）或体内（转移到受体母马后，再培养2天后检查IVP胚泡，n=3)。在IVD早期胚泡中，SOX-2阳性细胞在ICM中被GATA-6阳性细胞包围，在一些推测的PE细胞中与SOX-2共表达。在IVD胚泡中，SOX-2表达式是压缩的推定EPI所独有的，而GATA-6和CDX-2的表达与PE和TE规格一致，分别。在IVP胚泡中，SOX-2和GATA-6阳性细胞混杂且相对分散,SOX-2或GATA-6的共表达在一些CDX-2阳性TE细胞中是明显的。IVP囊胚的TE和总细胞数量低于IVD囊胚，并显示出较大的平均EPI细胞间距离；这些特征在发育较慢的IVP囊胚中更为明显。将IVP胚泡转移到受体母马中导致SOX-2阳性细胞压缩到假定的EPI中，而延长的体外培养没有。总之,IVP马胚胎的ICM致密性差，EPI和PE细胞混合；特征在缓慢发育的胚胎中得到强调，但通过转移到受体母马来弥补。
