tectum

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

花粉外由顶盖、柱状、底及外所组成。

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

花粉的外分为外和，外括覆盖、基粒棒和基足等三，一。

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

被盖—顶盖—被盖的联系与上丘中、深有关。