短语词组短语leaf epidermis piliferous cell 叶鳞毛embryo skin epidermis stem cell 胚胎皮肤表皮干细胞epidermis cell layer 表皮细胞层onion epidermis cell 洋葱表皮epidermis cell wall 表皮细胞壁human epidermis cell culture 表皮细胞培养 返回 epidermis cell