Musculature and Neurotransmitters in the Reproductive System of Trematodes

Abstract

The article analyzes own and published data concerning muscle elements present in various parts of the trematode reproductive system. The data on the presence of serotonergic and peptidergic (FMRFamidergic) nerve elements evidence the innervation of the trematode reproductive system departments by these neurotransmitters. The available literature information was supplemented by results of the study carried out on Prodistomum alaskense, a representative of the family Lepocreadiidae, an intestinal parasite of deep-sea fish (Zaprora silenus and Aptocyclus ventricosus). The localization of serotonergic and FMRFamidergic nerve structures was determined by immunocytochemistry. The musculature was stained using TRITC (tetramethylrhodamine-isothiocyanate) conjugated phalloidin. The slides were examined using a fluorescent microscope and a confocal laser scanning microscope. An analysis of the data and information in the literature suggest that the muscular system of the reproductive system is well developed in trematodes of various taxonomic groups and represented by circular, longitudinal, and, in some cases, by diagonal muscle fibers. The musculature of the trematode reproductive system is innervated by serotonergic and peptidergic (FMRFamidergic) neurons and their fibers which may be involved in regulating the contractile activity in various parts of the trematode reproductive system.

The organization of the muscle system of the causative agent of dicrocoeliosis, Dicrocoelium dendriticum

“…The presence of the muscles in the terminal sections of the reproductive systems has been established previously by light microscopy (Yastrebov & Yastrebova, 2014). The phalloidin‐stained musculature of the reproductive system was revealed in trematodes of various taxonomic groups: Cryptocotyle lingua , Echinoparyphium aconiatum , Allocreadium isoporum , Paramphistomum cervi , S. mansoni , F. hepatica , Echinostoma caproni , D. subclavatus , Prosorhynchoides (= Bucephaloides ) gracilescens , and Microphallus piriformes (Krupenko, 2014; Mair, Maule, Shaw, Johnston, & Halton, 1998; Ŝebelová et al, 2004; Stewart et al, 2003; Terenina & Gustafsson, 2014; Tolstenkov et al, 2007). The diagonal muscles were not previously reported in the reproductive structures.…”

“…The circular muscles form a sphincter around the excretory pore in E. aconiatum , Plagiorchis laricola , P. alaskense , D. subclavatus , and Lecithochirium sp. (Krupenko, 2014; Nefedova et al, 2021; Terenina & Gustafsson, 2014; Yastrebov & Yastrebova, 2014). In D. dendriticum , the circular and longitudinal muscles were observed in the terminal section of the excretory canal leading to the excretory pore.…”

“…The hermaphroditic reproductive system of the trematodes is quite complex and consists of the male (the testes, vas deferens, seminal vesicle, and cirrus) and female organs (the ovary, oviducts, vitelline glands, ootype, uterus, seminal receptacle, and Mehlis glands). In (Krupenko, 2014;Mair, Maule, Shaw, Johnston, & Halton, 1998;Ŝebelová et al, 2004;Stewart et al, 2003;Terenina & Gustafsson, 2014;Tolstenkov et al, 2007). The diagonal muscles were not previously reported in the reproductive structures.…”