Surface ultrastructure of Heterophyes nocens (Trematoda: Heterophyidae)

Cranial ultrasound findings in preterm germinal matrix haemorrhage, sequelae and outcome

Germinal matrix-intraventricular haemorrhage (GMH-IVH), periventricular haemorrhagic infarction (PHI) and its complication, post-haemorrhagic ventricular dilatation (PHVD), are still common neonatal morbidities in preterm infants that are highly associated with adverse neurodevelopmental outcome. Typical cranial ultrasound (CUS) findings of GMH-IVH, PHI and PHVD, their anatomical substrates and underlying mechanisms are discussed in this paper. Furthermore, we propose a detailed descriptive classification of GMH-IVH and PHI that may improve quality of CUS reporting and prediction of outcome in infants suffering from GMH-IVH/PHI.

Taxonomic tools for the identification of Allogenarchopsisbareilliensis n. sp. (Digenea: Hemiuroidea: Derogenidae) from Channastriata of Rohilkhand, India based on light and scanning electron microscopic studies

The stomach of the freshwater snakehead murrel, Channastriata (n = 250) collected from fresh water habitats of Bareilly, Uttar Pradesh, India revealed Allogenarchopsis, a trematode parasite (Plagiorchiida: Derogenidae). An illustrated account of light (Olympus BX-53 with Cellsens software imaging system) and scanning electron microscopy (SEM) (Neo JCM-6000) of Allogenarchopsisbareilliensis n. sp. (prevalence 37 %, intensity 1-4 par/host) is provided. Light microscopy based studies warranting creation of a new species are the robust shape of the body with broad mid-body, blunt anterior and tapering posterior end, large ventral sucker, ratio of oral sucker: ventral sucker 1:3.5, pharynx broader than long, egg size small with relatively short egg filament, excretory vesicle U-shaped bifurcating at posterior end and terminating above intestinal shoulders. Key characteristics of the tegumental microtopography by SEM are (1) an aspinous tegument with a variety of papillae of different shapes (button-like, dome-shaped) distributed randomly on the dorsal and ventral surface (2) oral sucker and oral cavity muscular with fringed margins and morphologically different oral papillae (3) lip of ventral sucker papillated including two unequally spaced rows of papillae with sensory receptacles interspersed in between, (4) unique differentially texturized cytoplasmic processes on the ventral sucker and (5) body folds grooved, gradually becoming narrower towards posterior end. This is the first record and study on Allogenarchopsis from Channa of Rohilkhand, India using electron optics. We recommend that the newly recognized morphological features as revealed by light microscopy and SEM be utilized as taxonomic tools in future for the identification of the species.

Topography and ultrastructure of the tegument of Deropristis inflata Molin, 1859 (Digenea: Deropristidae), a parasite of the European eel Anguilla anguilla (Osteichthyes: Anguillidae)

The tegumental ultrastructure of the intestine fluke Deropristis inflata was studied using scanning and transmission electron microscopy. The surface of the tegument was covered by transverse cytoplasmic ridges from which protrude numerous thorn-like spines showing crenelated tips on the posterior part. Spines were arranged in staggered rows. Cobblestone-like units of the tegument were observed on a semicircle-shaped formation over the oral sucker. A tegumental excrescence was observed in the dorsal anterior side of the fluke. Ultrastructural study revealed that the tegument of D. inflata had a typical syncytial organization with a distal cytoplasm lying over a basal matrix and cytons. Cytoplasmic bridges allowed transit of secretory vesicles and granules packed in gland cells. Two types of sensory structures were examined. Type 1 sensory receptor was a button-like uniciliated papilla mounted on a folded tegumental base and surrounded by cytoplasmic ridges. This receptor consisted of a nerve bulb and a cilium that extended from a centriole. Type 2 sensory receptor was a smooth bulb-like non-ciliated papilla. It was only recovered on the ventral sucker. This receptor consisted of a nerve bulb enclosing an ovoid electron-dense structure. For both receptors, the nerve bulbs contained numerous mitochondria, nerve fibers, and electron-lucent material. Particular distributions of the sensory receptors were observed with a concentration on the anterior third of the body around the oral and ventral suckers. Diagrams were made to help in understanding the nature of these structures.

Topography and ultrastructure of the tegument of Lecithochirium musculus (Digenea: Hemiuridae), a parasite of the European eel Anguilla anguilla (Osteichthyes: Anguillidae)

The tegumental ultrastructure of the stomach fluke Lecithochirium musculus was studied using scanning and transmission electron microscopy. The surface of the tegument was smooth and covered by transverse cytoplasmic ridges. Cobblestone-like units of the tegument were observed on the ventral surface. Invagination and evagination of the ecsoma induced variations in the tegumental surface. The ultrastructural study revealed that the tegument of L. musculus had a typical syncytial organization with a distal cytoplasm lying over a basal matrix and cytons. Two types of intra-tegumental sensory structures were observed. Type 1 sensory receptor was a domed-like fusiform structure consisting of a smooth elevation of the tegument. Four receptors of this type were observed on the anterior dorsal surface of the fluke. Three nerve bulbs filled with electron-lucent material and mitochondria composed this receptor. Hemispherical electron-dense collars were observed at the top of the nerve bulbs. Striated rootlets laid just beneath the hemispherical electron-dense collars. Type 2 sensory receptor presented two morphological variations, i.e., a bulb-like monolobed structure, and a bulb-like bilobed structure observed at two different degrees of evagination. For both variations, the nerve bulb enclosed mitochondria, electron-lucent material, and a conical electron-dense collar from which extended a striated rootlet. Numerous sensory receptors of this type were observed around the ventral sucker.

Tegumental ultrastructure of adult Gynaecotyla squatarolae (Digenea: Microphallidae)

Gynaecotyla squatarolae (Digenea: Microphallidae) adult flukes were recovered from experimental chicks at day 4-6 post-infection and their tegumental ultrastructure was observed with a scanning electron microscopy. They were pyriform in shape, and their anterior halves were concaved ventrally. The whole body surface was covered with tegumental spines, which were wide and 16-17 digitated between oral and ventral suckers. The density of spines and number of digits decreased posteriorly. The oral sucker was subterminal and the excretory pore was at the posterior end of the worm. Two ventral suckers were similar in appearance and protruded near midline of the worm. The genital atrium was dextral to the small ventral sucker. The dorsal surface was covered with tegumental spines, but the spines were sparser than on the ventral surface. On the middle portion of the dorsal surface, a small opening presumed to be the Laurer's canal was seen. From these findings, it has been confirmed that the adult G. squatarolae has unique characteristics in the surface ultrastructure.

REDESCRIPTION AND SURFACE ULTRASTRUCTURE OF PYGIDIOPSIS MACROSTOMUM (DIGENEA: HETEROPHYIDAE)

Pygidiopsis macrostomum Travassos, 1928, a poorly known species originally described from a single specimen from Rattus norvegicus (Erxleben, 1777) in Brazil, is redescribed on the basis of metacercariae from the mesenteries of naturally infected guppies Poecilia vivipara Bloch and Schneider, 1801 (Poeciliidae), and adults obtained from an experimental infection of hamsters. Pygidiopsis macrostomum is characterized by the absence of oral spines, vitellaria extending forward to ventral sucker, uterus reaching pharyngeal level, X-shaped excretory vesicle, and an oral sucker/acetabulum ratio of 1:0.8. The surface ultrastructure shows that the tegument of the metacercaria does not strongly differ from that of adults. The brush-shaped spines of P. macrostomum are similar to those reported for Pygidiopsis summa and Pygidiopsis ardeae, but no differences in spine shape were observed throughout the body.

Surface ultrastructure of the adult stage of Acanthotrema felis (Trematoda: Heterophyidae)

The surface ultrastructure of Acanthotrema felis (Trematoda: Heterophyidae) adults, recovered from a kitten experimentally infected with the metacercariae, was observed using a scanning electron microscope. The worm was leaf-like, ventrally concave and covered with scale-like multi-pointed tegumental spines. The spines on the anterior surface were short but broad, and had 10-12 pointed tips. The cytoplasmic processes protruded around the spines, like pockets for the spines. The ventrogenital opening was crescent, or kidney-shaped, and had protuberances with minute spines on its surrounding tegument. The spines on the posterior surface were long, but narrow, with 6-8 pointed tips. The cytoplasmic processes on this tegument were ridge-like, and elevated along the row of the spines. The surface ultrastructure of A. felis is generally similar to that of other heterophyid flukes, but some features are characteristic, and may be of taxonomic and bio-ecological significance.

Surface ultrastructure of Pygidiopsis summa (Digenea: Heterophyidae) adult flukes

A scanning electron microscopic study was performed on the surface ultrastructure of Pygidiopsis summa (Digenea: Heterophyidae) adults. Metacercariae were collected from gills and muscles of mullets (Mugil cephalus) caught in a known endemic area, and adult flukes were harvested from dogs after 8 weeks of experimental infection. The worm was calabash form with its posterior part broader than the anterior part. Tegumental spines were densely distributed over the body surface, except on the suckers and genital apparatus, and around the excretory pore. Well differentiated spines were observed on the anterior half of the body, with 14-16 tips ventrally, and 19-20 tips dorsally. On the oral sucker, three pairs of type I sensory papillae (uni-ciliated knob-like swellings) and one pair of type II sensory papillae (aciliated round-swellings) were observed on the anterior and posterior parts of the lip, respectively. On the lip of the ventral sucker, one pair of type II sensory papillae was distributed only on its posterior part. Sperms were seen emerging from or entering into the genital apparatus. The results showed that the surface ultrastructure of P. summa was unique among the heterophyid trematodes, especially in digitation of tegumental spines and in distribution of sensory papillae on oral and ventral suckers.

Food-borne intestinal trematode infections in the Republic of Korea

A total of 19 species of food-borne intestinal trematodes have been reported in humans in the Republic of Korea. They include 12 species of the Heterophyidae, Metagonimus yokogawai, M. takahashii, M. miyatai, Heterophyes nocens, H. heterophyes (imported), H. dispar (imported), Heterophyopsis continua, Pygidiopsis summa, Stellantchasmus falcatus, Centrocestus armatus, Stictodora fuscata, and S. lari; four species of the Echinostomatidae, Echinostoma hortense, E. cinetorchis, Echinochasmus japonicus, and Acanthoparyphium tyosenense; and one species each of the Neodiplostomidae, Neodiplostomum seoulense, Plagiorchiidae, Plagiorchis muris, and Gymnophallidae, Gymnophalloides seoi. Fresh water fish harbor the metacercarial stage of M. yokogawai, M. takahashii, M. miyatai, C. armatus, E. hortense, E. cinetorchis, E. japonicus, or P. muris. Brackish water fish serve as the second intermediate hosts for H. nocens, H. continua, P. summa, S. falcatus, S. fuscata, and S. lari. Brackish water bivalves are the source of infection with A. tyosenense. Tadpoles and frogs are the second intermediate hosts for N. seoulense, but the major source of human infection is the grass snake Rhabdophis tigrina, a paratenic host. The metacercariae of G. seoi are observed in oysters. The natural definitive hosts are, in most cases, mammals such as rats, cats and dogs. However, several species (C. armatus, S. lari, E. japonicus, A. tyosenense, and G. seoi) have birds as natural definitive hosts. Host-parasite relationships, pathogenesis and pathology, immunity, clinical aspects, differential diagnosis, treatment, prevention and control of these intestinal trematodes are briefly discussed.

Surface morphology of Probolocoryphe uca (Sarkisian, 1957) (Digenea: Microphallidae) from Kuwait bay

The surface ultrastructure of Probolocoryphe uca (Digenea: Microphallidae), recovered from a rat experimentally fed on crabs, Nanosesarma minutum (Brachyura: Grapsidae), naturally infected with the metacercariae, was studied by scanning electron microscopy. The flukes were leaf-like, ventrally concave and pyriform or ovoid in outline. The anterior end was modified into a sucker-like organ, comprising a protrusible disc-shaped structure surrounded by single-pointed spines. This organ is probably involved in the attachment and feeding process in a manner similar to the action of the oral suckers. Apart from the sucker-like organ, the entire tegumental surface was covered with triangular spines with multi-pointed tips. Ciliated, dome-shaped papillae were observed, singly or in groups, arranged symmetrically on the sucker-like organ and around the oral and ventral suckers. Kuwait Bay constitutes a new geographical record and the crab N. minutum is a new second intermediate host record for P. uca.

Surface ultrastructure of Stictodora tridactyla (Trematoda: Heterophyidae) from Kuwait Bay

The surface morphology of Stictodora tridactyla recovered from a kitten that was fed the killifish, Aphanius dispar, naturally infected with the metacercariae was studied using scanning electron microscopy. The body comprised a rounded head, elongate neck, and widely pyriform hind-body. The head bore a circular oral sucker on the ventral side, and concentric rows of peg-like cephalic spines on the dorsal side. The oral sucker was armed with pre-oral spines similar in shape and size to the cephalic spines. The neck and hind-body were densely covered with scale-like multipointed spines, the size and density of which decreased from anterior to posterior parts of the body. Ciliated dome-shaped papillae were found solitarily or as conjugated groups on the head apex and lips of the oral sucker. Non-ciliated dome-shaped papillae were restricted to the lower lip of the oral sucker. The body was devoid of a ventral sucker. The genital opening appeared as a round depression of the tegument at about the anterior third of the body. This is the first record of the occurrence of S. tridactyla in the Arabian Gulf region and A. dispar is a new second intermediate host.

Surface ultrastructure of Metagonimus takahashii metacercariae and adults

A scanning electron microscopic study was performed on the surface ultrastructure of metacercariae and adults of Metagonimus takahashii. Metacercariae were collected from the scale of crucian carp (Carassius auratus), and adult flukes were harvested 1-4 weeks after infection to rats. In excysted metacercariae, the oral sucker had type I (numerous) and type II (seven in total) sensory papillae. Tegumental spines were dense and digitated into 5-7 points on the surface anterior to the ventral sucker, but became sparse and less digitated posteriorly toward the end of the body. In adults, seven type II sensory papillae were characteristically arranged around the lip of the oral sucker, and on the inner side of the lip four small and two large type I sensory papillae were symmetrically seen on each side (12 in total). Tegumental spines on anterior two-thirds of the body, were digitated with 9-12 tips ventrally and 8-13 tips dorsally. Sperms entering into the Laurer's canal were observed. The results show that the surface ultrastructure of M. takahashii is generally similar to those of M. yokogawai and M. miyatai except for the digitation of tegumental spines.

Surface ultrastructure of Metagonimus miyatai metacercariae and adults

A scanning electron microscopic study was performed to observe surface ultrastructures of excysted metacercariae and adults of Metagonimus miyatai. Metacercariae were collected from the scale of the pale chub (Zacco platypus), and adult flukes were harvested 1-4 weeks after infection to rats. In excysted metacercariae, the oral sucker was devoid of tegumental spines and had type I and type II sensory papillae. Anteriorly to the ventral sucker, spines were dense and digitated into 5-7 points, whereas near the posterior end of the body spines were sparse and digitated into 2-3 points. In one-week adults, 7 type II sensory papillae were arranged around the lip of the oral sucker, and at inner side of the lip one pair of small and two pairs of large type 1 sensory papillae were seen on each side. The distribution of tegumental spines was similar to that of metacercariae, but they were more differentiated with 9-11 pointed tips. In two- to four-week old adults, the surface ultrastructure was nearly the same as in one-week old adults, however, sperms were frequently seen entering into the Laurer's canal. Conclusively, the surface ultrastructure of M. miyatai was generally similar to that of M. yokogawai, however, differentiation of tegumental spines and distribution of sensory papillae around the oral sucker were different between the two species, which may be of taxonomic significance.

Centrocestus formosanus: surface morphology of metacercaria, adult and egg

The surface morphology of metacercariae isolated from Puntius spp., adult worms from infected hamsters and eggs of Centrocestus formosanus (Digenea: Heterophyidae) were studied using scanning electron microscopy. It was found that the surfaces of the metacercariae and adult worms were closely similar in appearance. The oral sucker was surrounded by a circumoral expansion with two rows of 32 spines (16 spines each). The ventral sucker, with six large nonciliated papillae on the lip, and the genital opening were located mid-ventrally. The excretory pore was terminal. The body surface was covered with pectinate scale-like spines of varying sizes. The scales in the middle area were larger than those in the anterior and posterior parts of the body. Sensory papillae, mostly uniciliated, were present in greater abundance at the anterior region of both stages. However, morphological variations were observed among the adults depending on the age of the worms. At 4 weeks, the oral sucker and circumoral expansion were cobblestone-like in structure and the grooves of spines split compared with their smooth surfaces at 10 days. In addition, the ventral sucker became depressed and its large papillae on the lip disappeared at 10 weeks post infection. Multiciliated papillae were also present in 10-week old worms. Each egg of this parasite possessed a prominent operculum and a latticed design on the egg shell.