常见例句用作名词 (n.)The pronephros does not function, but it marks at the fourth week of development the start of renal development.前肾生肾节内，从头侧至尾端先后出现横行前肾小管，内侧端开口于胚内体腔，外侧端与头尾走行的前肾管相通。 返回 pronephroi