An Majumdar, S. K. creator Lowry, R. J. text ag 2006 continuing eng 5 páginas Ultrastructure studies of the pollen grains of Gasteria armstrongii revealed the existence of a barrier between the vegetative and generative nuclei. The layer is continuous with the intine of the pollen wall. It is suggested that the cisternae of the endoplasmic reticulum appear between the two nuclei and deposition of pectic substances occurs in them. Later the pectine containing cisternae line up in the equatorial region and fuse to from the layer. Finally the layer separates from the intine and becomes the envelope around the generative nucleus. The chemical nature of the barrier is discussed. fot. byn. Gasteria Liliaceae Polen 0031-9457 238927 v. 28 n. 2 (1971) AR-ReUNN 260630 20260702003308.0 239009 spa