Morphological features of the testis of freshwater blood flukes of the genus Sanguinicola Plehn, 1905, with consideration of the testicular patterns in the Aporocotylidae.

This is the first detailed study assessing the morphological features of the testis and testicular sperm of members of the freshwater blood flukes Sanguinicola sp. from Leuciscus idus (Cyprinidae) and for S. volgensis from Pelecus cultratus (Cyprinidae), and the marine blood fluke Aporocotyle simplex from Hippoglossoides platessoides (Pleuronectidae).

Interrelationships of vitelline and muscle cells within the vitelline follicles of the blood fluke Aporocotyle simplex (Digenea, Aporocotylidae) and morphological evidence for the modification of vitelline material for eggshell formation.

This study of the fish blood fluke Aporocotyle simplex represents the first detailed transmission electron microscopical (TEM) investigation of the vitellarium of an aporocotylid digenean blood fluke. It revealed some unusual characteristics in the cytoarchitecture of the vitelline follicles and demonstrated modifications of the vitelline granules for eggshell formation. The vitelline follicles consist of vitellocytes at different developmental stages surrounded by sarcoplasmic processes of myocytes which occur throughout each follicle.

Gyrodactylus triglopsi n. sp. (Monogenea: Gyrodactylidae) from the Gills of Triglops nybelini Jensen, 1944 (Teleostei: Cottidae) in the Barents Sea.

Introduction: Monogeneans of the genus Gyrodactylus were found on the gills of specimens of the bigeye sculpin Triglops nybelini Jensen, 1944 caught by trawl in the Barents Sea in January-February 2016.

Methods: Morphological preparations of the parasites were examined and photographed under a microscope at magnifications of × 100-1000 and morphometric analyses were carried out on 22 specimens using ImageJ2 software. Eight of the specimens used for the morphological comparisons were also subjected to molecular analyses by sequencing a region of the ribosomal DNA spanning partial 18S, the internal transcribed spacers 1 and 2 (ITS1 and 2), 5.

Unique ultrastructural characteristics of the tegument of the digenean blood fluke Aporocotyle simplex Odhner, 1900 (Digenea: Aporocotylidae), a parasite of flatfishes.

This paper includes the first transmission electron microscopical (TEM) study of the tegument of a member of the basal digenean family Aporocotylidae. Scanning electron microscopical investigations of the fish blood fluke Aporocotyle simplex show that each boss on the lateral body surface bears 12-15 simple, uniform spines which extend from 0.5-2.

The first ultrastructural observations of the egg-forming complex of Calicotyle affinis, an endoparasitic monocotylid monogenean which lacks a uterus.

This ultrastructural study of the female reproductive system of Calicotyle affinis, a monogenean without a uterus, demonstrates, for the first time in a monogenean, the presence of accessory cells located in the peripheral region of the ovary and a single large cell whose surface is penetrated by deep invaginations which restrict the passage of oocytes through the lumen of the distal extremity of the ovary. The cytoarchitecture of the epithelial lining of the two vaginae is a syncytium formed by an anucleate epithelial lining with sunken epithelial perykaria. The wall of the seminal receptacle is an enlarged prolongation of the vaginal epithelial lining.