Part of the apical pore complex (APC); a feature located on the epitheca of many marine, armoured (thecated) dinokont species. The Po houses an apical pore (ap), and often times, small periferal pores. The Po can be long and narrow, as in Ostreopsis spp., or wide and triangular, as in Gambierdiscus spp.

Alternative form for apical pore plate : Po.