tectum

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

花粉壁由顶盖、柱状、底及壁内所组成。

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

花粉壁的壁分和内，包括覆盖、棒和足等三，内只包含一。

6.The tegmentum——tectum——tegmentum connections are only concerned with the mid-dle and deep layers of the superior colliculus.

被盖—顶盖—被盖的联系只与上丘中、深有关。