tectum

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

花粉外壁由顶、柱状、底及外壁所组成。

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

花粉壁的外壁分为外，外包括、基粒棒基足等三，只包含一。

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

被—顶—被的联系只与上丘中、深有关。