File:Trichoplax revised anatomy.png

English: Placozoans possess two epithelia, an upper epithelium facing the water and a lower epithelium facing the substrate. The traditional schematic cross section of a Placozoon shows a single fiber cell layer sandwiched between these layers. Recent studies by Guidi et al., however, have shown that all morphologically studied genetic lineages, including the lineage originally used by Grell and Benwitz, actually possess several fiber cell layers. The given drawing thus represents the revised cross section of a typical placozoan specimen. It was also previously shown that the small marginal cells might represent the formerly described pluripotent stem cells. ue = upper epithelium; le = lower epithelium; fc = fiber cells; mc = marginal cells; ss = shiny sphere.