Teratomas are more or less normal bodily structures-eyes or teeth , for example-that are growing in the wrong place .

畸胎瘤是更加正常或更加不正常的组织结构---眼睛或者牙齿，例如--在错误的地方生长。

However , in some cases , the cells formed clumps of cancerous tissue called teratomas , a major safety concern with stem cell therapies .

然而，某些情况下，这些细胞形成了称作畸胎瘤的癌变肿块，这也是干细胞疗法的一个主要安全问题。

The real test will be to inject these cells into mice and see if they form teratomas tumours containing tissue or structures derived from all three germ layers .

有说服力的实验是把这些细胞注射到大鼠体内，看是否能形成畸胎瘤---包含从三种干细胞发育而来的组织或结构的肿瘤。