Figure 5.

Plant tissue. Immature xylem vessel element in production. The central decaying materials are remnants of the parent xylem cell with thickened cellulose walls, most likely from the resin-producing leguminous tree Hymenea sp. They shortly would have disappeared if they had not been trapped in amber and preserved for 20 million years. Pit connections between the xylem elements of the plant cell wall (w) are visible at the white arrows. (Bar = 25 μm.) Image was produced by transmission electron microscopy.