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

Abstract

Some organs of the reproductive system of the protogynous monogenean skin parasite Macrogyrodactylus congolensis (Prudhoe, 1957) Yamaguti, 1963 have been studied using transmission electron microscopy. The vesicula seminalis is enclosed by a prominent layer of circular muscle fibres and has inner syncytial protrusions. The penis bulb is a highly muscular organ with prominent radial and circular muscle fibres, a gutter-shaped large spine and 16 small spines. Two syncytial male accessory glands, and a single reservoir for male accessory secretion were identified. The secretory bodies in the male accessory glands and male accessory reservoir have a unique structure. A large oocyte is situated in a chamber, previously referred to as the "ootype" or "egg-cell-forming region" (ECFR), which also contains one or two small undifferentiated cells and vacuolated tissue. Mature spermatozoa were abundant in the receptaculum seminis and dispersed in the vacuolated tissue in the ECFR and appeared to be attached to the membrane of the large oocyte. Mature spermatozoa were also seen in the parenchymal tissue near the chamber containing embryos and even in the tissues of the embryo.

Novel distribution records and molecular data for species of Macrogyrodactylus Malmberg, 1957 (Monogenea: Gyrodactylidae) from Clarias gariepinus (Burchell) (Siluriformes: Clariidae) in southern Africa

“…Figs. 2D-F, 3B,D(ii); (1999, 2001a,b, 2004b, 2007, 2017, 2019), Hagras et al (1999), Arafa (2000Arafa ( , 2011, Arafa et al (2003Arafa et al ( , 2013Arafa et al ( , 2014 Morphological observations (measurements provided in Table 5): Morphology of haptoral sclerites similar to illustrations provided in description of Prudhoe (1957). Hamulus complex of M. congolensis large in size, has slender hamuli less sharply curved into point and root, armed with 16 marginal hooks.…”

Light and scanning electron microscopy of the effects of Macrogyrodactylus congolensis (Prudhoe, 1957) on the skin of the African sharptooth catfish Clarias gariepinus (Burchell, 1822)

“…These parasites proliferated in the favourable conditions of the aquarium tanks. These monogeneans reproduce through polyembryony similar to all other Gyrodactylidae (Bakke et al., 2007; Cable & Harris, 2002), enabling them to reach large numbers in a short space of time and pose a threat to the fish host (Arafa et al., 2014). Similarly, a hyper‐infection of Macrogyrodactylus polypteri Malmberg, 1957 on Polypterus senegalus (Cuvier, 1829) in an aquarium in Sudan accumulated from 690 to 7340 macrogyrodactylids per fish in a period of 20–25 days, resulting in fish fatalities (Khalil, 1964).…”