Features of the Organization of the Tegument in Cystacanth and Adult Acanthocephalan Acanthocephalus tenuirostris

Abstract—A comparative light- and electron-microscopic study of the tegument of a formed cystacanth and a mature acanthocephalan Acanthocephalus tenuirostris (Achmerov et Dombrowskaja–Achmerova, 1941) is carried out. It is shown that, in addition to morphometric differences, the tegument of cystacanth differs from that of the adult acanthocephalan by the terminal expansions of invaginates of the outer tegument membrane, presumably due to the secretion of glycocalyx material. In the tegument of an adult acanthocephalan, a process of detachment of small fragments from the nuclei is found, which may be an analogue of the well-known process of nuclear fragmentation that occurs at the early stages of postembryonic development. It is shown that, in many cases, tegument lacunae are not completely limited by dense formations resembling fibrils on sections.