Distribution of acetylcholinesterase activity during the development of cysticercoids of Hymenolepis diminuta (Cestoda)

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.

Accumulation and utilization of lipids during the development of Hymenolepis diminuta cysticercoids

“…Similar cell types were found in young cysticercoids of Hymenolepis citelli (Collin 1970), H. microstoma (Caley 1974), Raillietina cesticillus (Baron 1971), and Moniezia expansa (Caley 1976). By means of histochemical methods Moczoñ and OEwietlikowska (2006) examined the distribution of the activity of acetylcholinesterase (AChE) in the developing cysticercoids of H. diminuta. They demonstrated an expression of the enzyme in a population of non-neural cells, which gradually spread all over the internal wall of the cyst cavity and, finally, they become arranged in a thin cyst cavity lining.…”

“…The expression of AChE begins in somewhat older, i.e. worm-shaped cysticercoids and it takes place first in two and then in four short longitudinal strands of the differentiated cells occupying the area of the prospective cyst (Moczoñ and OEwietlikowska 2006). Perhaps there is no simple relation between the activity of AChE and the storage and mobilization of lipids in the lining-forming cells.…”