The axial plate is a structure within some species of Gomphoneis. The term refers to the internal 'plate' of silica that occludes the areolae internally. The margin of the axial plate results in the longitudinal line, visible in light microscopy.
Image Credit: Sarah Spaulding
Internal view of the central area of Gomphoneis herculeana showing the proximal raphe ends. The axial plate covers the internal expression of the areolae.
Image Credit: Pat Kociolek
The axial plate forms the longitudinal lines in Gomphoneis. Here the longitudinal lines are shown in G. herculeana.