胚胎干细胞起源的探讨

目前胚胎干细胞(ESCs)建系的取材来源包括桑椹胚的卵裂球、囊胚的内细胞团(ICM)、上胚层细胞和原始生殖细胞(PGCs)，甚至从新生鼠睾丸细胞也分离得到类ES样细胞系。这就提出了一个问题，什么是ESCs最接近的体内细胞来源。传统观念常常把ESCs等同于ICM细胞，也有学者认为ESCs更象上胚层细胞，而在已知的分子标记基因方面，ESCs所具有的特征更接近体内早期生殖细胞。不清楚ESCs最接近的体内细胞来源，可能是制约许多品系小鼠和大多哺乳类动物建系成功率提高的原因之一。ESCs系与EG细胞系的分离条件不同表明，加强对ESCs多能性维持基因调控研究具有重要意义。本文从ESCs的经典概念及其发展，早期胚胎细胞和生殖细胞发育规律，早期胚胎细胞、早期生殖细胞和ESCs的关系等方面进行综合分析，认为ESCs可能有多种接近的体内细胞来源。进一步应通过对ESCs建系不同的取材细胞和不同品系的ESCs间进行比较研究，以便弄清ESCs的来源和转化机制，为提高不同物种ESCs建系效率提供理论支持。

The Origin of Embryonic Stem Cells

The inner cell mass(ICM),blastomeres,epiblasts and primordial germ cells(PGCs) are usually used as primary materials for the establishment of embryonic stem cell(ESC) lines.ES-like cells have even been isolated from neonatal mouse testis.ESC are traditionally regarded as ICM cells,though some scholars believe they more closely resemble cells from the epiblast.However,recent evidence of ESC molecular markers indicate that the characteristics of ESC resemble those of early germ cells.The unknown origin and nature of ESC may limit the successful establishment of ESC lines from many different species.Here we review the progress of research regarding embryonic pluripotent cells,early germ cells and ESC.We find ESC can be derived from many cell types.Future study should elucidate the origin of ESC by comparing different ESC lines so as to determine the nature of ESC and improve the efficiency of ESC derivation.