Neuromusculature of Macrogyrodactylus congolensis, a monogenean skin parasite of the Nile catfish Clarias gariepinus

Abstract

Phalloidin fluorescence technique, enzyme cytochemistry and immunocytochemistry, in conjunction with confocal scanning laser microscopy, were used to describe the neuromusculature of the monogenean skin parasite Macrogyrodactylus congolensis from the Nile catfish Clarias gariepinus. The body wall muscles are composed of an outer layer of compactly arranged circular fibres, an intermediate layer of paired longitudinal fibres and an inner layer of well-spaced bands of diagonal fibres arranged in two crossed directions. The central nervous system consists of paired cerebral ganglia from which three pairs of longitudinal ventral, lateral and dorsal nerve cords arise. The nerve cords are connected at intervals by many transverse connectives. Both central and peripheral nervous systems are bilaterally symmetrical and better developed ventrally than laterally and dorsally. Structural and functional correlates of the neuromusculature of the pharynx, haptor and reproductive tracts were examined. Results implicate acetylcholine, FMRFamide-related peptides and serotonin in sensory and motor function. The results were compared with those of Macrogyrodactylus clarii, a gill parasite of the same host fish C. gariepinus.

On some ultrastructural features of the reproductive system of the monogenean parasite Macrogyrodactylus congolensis from Clarias gariepinus inhabiting the River Nile in Egypt

“…The female reproductive system consists of a chamber containing a large egg cell (oocyte), a receptaculum seminis and the uterus containing developing embryos (E1-E4), one inside the other. For more details about the internal anatomy of M. congolensis at the light microscope level, see El-Naggar et al (1999).…”

“…Fins were also removed, immersed in river water in separate dishes and searched for parasites with a stereomicroscope. M. congolensis is protogynous and specimens selected for TEM were at the late male stage in which the male reproductive system was fully developed alongside the female system (see El-Naggar et al 1999). Specimens of M. congolensis were processed for TEM as follows: the parasites were washed using distilled water, then fixed in 2.5% glutaraldehyde buffered to pH 7.3 with 0.1 M sodium cacodylate-HCl buffer at 4°C for about 2 h. The specimens were washed for at least 1 h in several changes of cold buffer (0.1 M sodium cacodylate-HCl containing 3% sucrose and 0.1 M CaCl 2 ).…”

“…These parasites have been implicated as agents of fish diseases. Macrogyrodactylus clarii Gussev, 1961 from the gills, and Macrogyrodactylus congolensis (Prudhoe 1957) Yamaguti, 1963 from the skin and fins were recorded for the first time in Egypt by El-Naggar and Serag (1987) and El-Naggar et al (1999) respectively. Some previous accounts of M. congolensis were limited in scope (Prudhoe 1957, Yamaguti 1963, Thurston 1970, Douël-lou and Chishawa 1995.…”

“…Some previous accounts of M. congolensis were limited in scope (Prudhoe 1957, Yamaguti 1963, Thurston 1970, Douël-lou and Chishawa 1995. Other detailed anatomical studies (Arafa 2000;El-Naggar et al 2001a,b;Arafa et al 2003;El-Naggar et al 2007;Arafa 2011;Arafa et al 2013) did not focus on the ultrastructure of the reproductive system.…”

Neuroanatomy of Cornudescoides kulkarnii n. sp., a gill parasite of Mystus vittatus in Meerut (UP), India

“…These nerves are also responsible for coordination of muscular movements involved in the release of histolytic enzymes from the gland cells (cephalic glands) of the anterior adhesive apparatus. Extensive innervation of the head lobes, particularly the adhesive sac nerves, resembles that of M. clarii (El-Naggar et al 2004Arafa et al 2003) and M. congolensis (El-Naggar et al 2007). Contact perception (and possibly contact chemoreception) by the pro-haptor is likely to be important during temporary leech-like locomotion.…”