The cement apparatus of larval and adult Acanthocephalus anguillae (Acanthocephala), with notes on the copulatory cap and origin of gland secretion.

Light and electron microscopy were used to investigate the ultrastructure of the cement apparatus, namely cement glands and cement ducts, of mature specimens of the parasite Acanthocephalus anguillae (Muller, 1780) Luhe, 1911 recovered from the alimentary canal of fish Leuciscus cephalus (Risso, 1826). In addition, the cement apparatus of immature A. anguillae found within the body cavity of the crustacean Asellus aquaticus (L.) was examined. In immature and mature males of Acanthocephalus anguillae, there are six round cement glands and each of them has an outer cytoplasmic layer containing nuclei and surrounds a space for storage of the cement. The cytoplasmic layer produces round, membrane-bound secretory granules approximately 1 microm in diameter. Nuclei and other cellular organelles surrounded by secretory granules were noticed inside the luminal part of the gland of adult males. In some female Acanthocephalus anguillae, within the attached copulatory cap, eggs and spermatozoa were observed. A protein of about 23 kDa appeared to be the major component of proteins of isolated cement glands, as well as in detached copulatory caps.