Korean J Parasitol.  2018 Oct;56(5):463-475. 10.3347/kjp.2018.56.5.463.

Morphological Studies of Developmental Stages of Oculotrema hippopotami (Monogenea: Polystomatidae) Infecting the Eye of Hippopotamus amphibius (Mammalia: Hippopotamidae) Using SEM and EDXA with Notes on Histopathology

• Rubtsova N
• Heckmann R
• Smit WJ
• Luus-Powell WJ
• Halajian A
• Roux F

• KMID: 2426751
• DOI: http://doi.org/10.3347/kjp.2018.56.5.463

Abstract

The present study was performed to observe histopathological effects of Oculotrema hippopotami Stunkard, 1924 infection in the eye of Hippopotamus amphibius, as well as to reveal new details of morphology and structural features of this monogenean and its comparison between 2 age stages of the parasite. This was done using both light and scanning electron microscopy, energy dispersive X-ray analysis (EDXA) and histopathology. The presence of a mixture of different generations (adult and sub-adult) in one host individual is common for Oculotrema Stunkard, 1924 in contrast to Polystoma Zeder, 1800. New metrical and graphical information obtained for adults and sub-adults compared with the previous studies. Here we show the presence of genital papillae in adults, metrical data on the distal part of the vas deferens. SEM micrographs of sperm ejaculatory structures and information about the flattened dorsal side of the body provided for the first time. Histopathological changes, such as necrosis and hemorrhage in host tissues as a result of O. hippopotami attachment structures are described. Structural analysis of different body parts of O. hippopotami of both age groups are also included. We show qualitative differences in the presence of hardening ions (S, P, Ca) in attachment structures (oral and haptor suckers) that increase with the age of the worm. The presence of sub-adults and adults on the same host, together with high levels of infection without high pathogenicity may account for Oculotrema being one of the most successful parasites among the Monogenea.

Keyword

Oculotrema hippopotami; Hippopotamus amphibius; Polystomatidae; sub-adult; adult; histopathology; structural analysis; SEM; EDXA

MeSH Terms

Adult
Family Characteristics
Hemorrhage
Human Body
Humans
Ions
Microscopy, Electron, Scanning
Necrosis
Parasites
Spermatozoa
Vas Deferens
Virulence
Ions