The exine is composed of tectum, columellae, foot layer and endexine.

外壁由顶盖、柱状、及外壁所组。

The exine of pollen wall is of different electron density, the nexine dense and the sexine, comprising tectum, bacules, and foot layer, relatively thin.

壁的外壁分为外和，外包括覆盖、基粒棒和基足等三，只包含一。