There was lots of organelle, such as rib somes, mitochondria in companion cell during the mature stage of SE.Also the plasmodesmata appeared in cell wall between SE and CC.

• 在筛管成熟期间，伴胞的细胞质较浓，内含辜富的核糖核蛋白体、线粒体等细胞器，与筛管相连的细胞壁上具有胞间连丝。