Acta Parasitologica, Vol. 51, No. 2, 2006, 143-151 Tadeusz Moczon and Agnieszka Swietlikowska - Distribution of acetylcholinesterase activity during
the development of cysticercoids of Hymenolepis diminuta
W. Stefanski Institute of Parasitology, Polish Academy of Sciences, 51/55 Twarda Street, 00-818 Warszawa, Poland
*Corresponding author: moczon@twarda.pan.pl
ABSTRACT
The distribution of acetylcholinesterase (AChE) in oncospheres and developing cysticercoids of Hymenolepis diminuta was
examined. The enzyme was localized in the nervous system and in some non-nerve cells of these larvae. In oncospheres AChE
was detected in hook muscles and in the binucleated medullar center that is known to enclose two neurons. At early developmental
stages of the cysticercoids the enzyme was localized in the post-oncospheral hook muscles and in subtegumental muscle
fibers of the cercomer. At medium and late stages of development the activity of AChE was detected in the developing nervous
system and in two and, subsequently, in four populations of cells, which gradually spread over the whole internal wall of
the cyst, thus forming a thin multilayer AChE-positive lining of the cyst cavity. Following withdrawal of the scolex the lining
separates the parenchyma of the turned neck from the cyst tissues and remains AChE-positive during the whole life of the parasite,
i.e. up to the death of the infected host. The role played by non-neural AChE associated with the cyst cavity lining is
unknown, but seems to regulate both the transport of nutrients and minerals into the scolex and waste substances in the opposite
direction.
KEY WORDS: Cestoda, Hymenolepis diminuta, cysticercoids, acetylcholinesterase, histochemistry