Proplastid a self - duplicating undifferentiated plastid , about 0 . 5 - 1 m in diameter and found in the meristematic regions of plants . they grow and develop into plastids of different types 前质体：能够自我复制的没有分化的质体，直径约0 . 5 - 1微米，发现于植物分生组织区域。它们生长发育为不同类型的质体。
