These ingrowths extended into the lumen of central cell and fused with the linear endoplasmic reticulum(ER) by many electron-dense vesicles.

• 内质网线状排列，通过电子致密小泡相互连接； 同时，小泡将内质网和壁内突融合，成为垂周壁，将合胞体的胚乳分隔成一个个向心开口的圆柱体。