<div><p>Several inducers have been used to differentiate embryonic stem cells (ESCs) into male germ cells but the induction process has been inefficient. To solve the problem of low efficiency of inducer for ESCs differentiation into male germ cells, all-trans retinoic acid (ATRA), Am80(the retinoic acid receptor agonist), and estradiol (E2) was used to induce ESCs to differentiate into male germ cells <i>in vitro</i>. ESCs were cultured in media containing ATRA, Am80, or E2 respectively which can differentiate ESCs into a germ cell lineage. In process of ATRA and Am80 induction Group, germ cell-like cells can be observed in 10 days; but have no in E2 induction Group. The marker genes of germ cell: <i>Dazl</i>, <i>Stra8</i>, <i>C-kit</i>, <i>Cvh</i>, <i>integrinα6</i>, and <i>integrinβ1</i> all showed a significant up-regulation in the expression level. The ATRA-induction group showed high expression of <i>C-kit</i> and <i>Cvh</i> around 4 days, and integrinα6 and integrinβ1 were activated on day 10, respectively, while the E2-,Am80- induction group showed a high expression of <i>C-kit</i> as early as 4 days immunocytochemistry results shown that, <i>integrinα6</i> and <i>integrinβ1</i> could be detected in the ATRA-, Am80-, and E2-induction group, Positive clones in the ATRA group were greater in number than those in the other two groups. we conclued that ATRA, Am80, and E2 can promote the expression of the corresponding genes of germ cells, and had different effect on the differentiation of ESCs into male germ cells. ATRA was the most effective inducer of germ cell differentiation.</p></div
