It is hypothesized that this material is responsible for adhesion of the pit membrane to the surface of the pit border during the process of aspiration. AFM showed a discontinuous layer of non-microfibrillar material on the surface of both torus and margo. The former formed fascicles of fibrils that merged into even thicker buttresses during the act of pit membrane aspiration.
The margo consisted of radial microfibrils as well as finer diameter tangential fibrils. SEM and AFM views of the torus surface showed no plasmodesmatal openings, but branched, secondary plasmodesmata were occasionally noted using TEM in conjunction with ultrathin sections. Pit membranes contained tori that did not stain for lignin. Bordered pit pairs of Ephedra species were characterized using different types of microscopy.
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