[Studies on the fine structure of the nucleolus and the nucleolusorganizing region in Gnetum gnemon].

In Gnetum gnemon the nucleoli of tapetum cells and cells of the anther wall are made up during the interphase-stage of electron dense granules 18-20 nm in diameter and electron dense fibrils 8-10 nm in diameter. At the outside of the nucleolus or within it there can be found one to five distinct zones of low electron density (Fig. 1, LK). The LK is composed of ± tightly packed fibrils 7-8 nm in diameter. Nucleolus associated heterochromatin is never directly attached to the nucleolus but joined in certain cases through the LK.