At least two different states representing the epiblast progenitors in the blastocyst and the pluripotent progenitors of the later gastrulating embryo have been recognized.

• 最少两种代表不同的发育状态已得到确认，一种是胚泡中的外胚层祖细胞，另一种为晚期原胚多潜能祖细胞。