Spermatogenesis and the fine structure of the mature spermatozoon of the liver fluke, Fasciola hepatica (Trematoda: Digenea)

Parasitology ◽  
1990 ◽  
Vol 101 (3) ◽  
pp. 395-407 ◽  
Author(s):  
A. W. Stitt ◽  
I. Fairweather
Keyword(s):  
Fine Structure ◽  
Liver Fluke ◽  
Central Body ◽  
Fasciola Hepatica ◽  
Mature Spermatozoon ◽  
Basal Bodies ◽  
Nuclear Region ◽  
Sperm Ultrastructure ◽  
Transmission Electron ◽  
Median Process

SUMMARYSpermatogenesis and the fine structure of the mature spermatozoon of Fasciola hepatica have been studied by transmission electron microscopy. The primary spermatogonia display a typical gonial morphology and occupy the periphery of the testis. They undergo 3 mitotic divisions to give rise to 8 primary spermatocytes forming a rosette of cells connected to a central cytophore. The primary spermatocytes undergo 2 meiotic divisions, resulting in 32 spermatids that develop into spermatozoa. Intranuclear synaptonemal complexes in primary spermatocytes confirm the first meiotic division. The onset of spermiogenesis is marked by the formation of the zone of differentiation which contains 2 basal bodies and a further centriole derivative, the central body. The zone extends away from the spermatid cell to form the median process; into this migrates the differentiated and elongate nucleus. Simultaneously, 2 axonemes develop from the basal bodies. During development, they rotate through 90° to extend parallel to the median process. The migration of the nucleus to the distal end of the median process coincides with the fusion of the axonemes to the latter to form a monopartite spermatozoon. The mature spermatozoon possesses 2 axonemes of the 9 + ‘1’ pattern typical of parasitic platyhelminths, 2 elongate mitochondria and a variable array of peripheral microtubules. The nuclear region of the spermatozoon is immotile. The value of sperm ultrastructure as a taxonomic tool in platyhelminth phylogeny is discussed.

Ultrastructure of spermatogenesis and the mature spermatozoon of Haplobothrium globuliforme Cooper, 1914 (Cestoda: Haplobothrioidea)

1985 ◽  
Vol 63 (6) ◽  
pp. 1478-1487 ◽  
Author(s):  
Barbara M. MacKinnon ◽  
Michael D. B. Burt
Keyword(s):  
Volume Ratio ◽  
Mature Spermatozoon ◽  
Nuclear Volume ◽  
Sperm Cells ◽  
Basal Bodies ◽  
Sperm Ultrastructure ◽  
Cytoplasmic Extension ◽  
Transmission Electron ◽  
Regular Arrangement ◽  
Dense Nucleus

The process of spermatogenesis and the structure of the mature spermatozoon of Haplobothrium globuliforme Cooper, 1914 were examined using transmission electron microscopy. Spermatogonia have a low cytoplasmic to nuclear volume ratio, and contain numerous free ribosomes and few mitochondria. Quaternary spermatogonia have a rosette appearance with the eight nuclei surrounding a central cytoplasmic cytophore. Spermatocytes, the largest of the developing sperm cells, contain free ribosomes and several mitochondria with pronounced cristae. No synaptonemal complexes and few endoplasmic reticulum formations were seen. Early spermatids show a regular arrangement of the nucleus, Golgi apparatus, and mitochondria. This regularity is disrupted as spermiogenesis commences, with the formation of the zone of differentiation, a conical indentation of the spermatid cytoplasm. This zone of differentiation is bordered by microtubules. Within the zone develop two interconnected basal bodies with their respective flagellar rootlets. From each basal body arises an axoneme with the 9 + "1" microtubular configuration. The axonomes elongate, eventually fusing with a cytoplasmic extension of the zone of differentiation, and the condensed nucleus migrates into the sperm body. The mature spermatozoon is elongate (30 μm long) and slender, and possesses an electron-dense nucleus, two lateral axonemes, α and β glycogen, and peripheral microtubules. The importance of sperm ultrastructure with respect to phylogeny is discussed.

Spermiogenesis in two paramphistomes from Nile fish in Egypt: an ultrastructural study

2007 ◽  
Vol 81 (3) ◽  
pp. 219-226 ◽  
Author(s):  
A.A. Ashour ◽  
K. Garo ◽  
I.S. Gamil
Keyword(s):  
Electron Microscopy ◽  
Mature Spermatozoon ◽  
Basal Bodies ◽  
Sperm Ultrastructure ◽  
Parasitic Helminths ◽  
Ultrastructural Studies ◽  
Cytoplasmic Extension ◽  
Transmission Electron ◽  
Digenetic Trematodes ◽  
External Ornamentation

AbstractThe process of spermiogenesis in two paramphistomes,Sandonia sudanensisandBasidiodiscus ectorchisfrom the Nile fishSynodontis schallin Egypt was studied by transmission electron microscopy. Spermiogenesis is characterized by the outgrowth of the zone of differentiation, presenting two basal bodies separated by a microtubule organizing centre, each basal body developing into a flagellum. Proximodistal fusion of these flagella with a median cytoplasmic extension gives rise to the spermatozoon. The mature spermatozoon possesses two axonemes of the 9+‘1’ pattern typical of parasitic helminths. There are few ultrastructural studies on spermiogenesis in paramphistomes, which are considered the most primitive digenetic trematodes. The present study provides new and more detailed information on this process, including the presence of a lateral flange and external ornamentation of the cell membrane. The value of sperm ultrastructure as a taxonomic tool in phylogeny is also discussed.

scholarly journals Sperm ultrastructure of Pochazia shantungensis (Chou & Lu) and Ricania speculum (Walker) (Hemiptera, Ricaniidae) with phylogenetic implications

ZooKeys ◽  
2019 ◽  
Vol 880 ◽  
pp. 43-59
Author(s):  
Zhen Jiang ◽  
Jianing Liu ◽  
Daozheng Qin
Keyword(s):  
Neck Region ◽  
Mature Spermatozoon ◽  
Current Evidence ◽  
Sperm Ultrastructure ◽  
Transmission Electron ◽  
Phylogenetic Implications ◽  
Dense Substance ◽  
The Individual ◽  
Relationship Of ◽  
Centriole Adjunct

The sperm ultrastructure of two ricaniid species, Pochazia shantungensis (Chou & Lu) and Ricania speculum (Walker), was investigated using light and transmission electron microscopy. Both species have monoflagellate sperm, the shape and ultrastructure of the mature spermatozoon of these two species are similar in morphology, and 128 spermatozoa are organized into sperm bundles with their heads embedded in a homogenous matrix forming the spermatodesmata. The individual sperm is filiform and includes the head, neck and flagellum. The head is needle-like, with a bilayer acrosome and an inferior elongated nucleus which is formed of homogeneously compact and electron-dense chromatin. The neck region is indistinct and is comprised of the centriole and centriole adjunct with a homogeneous dense substance. The long flagellum has the typical 9 + 9 + 2 axoneme microtubule pattern and two symmetrical mitochondrial derivatives with an orderly array of cristae flanking both sides, and a pair of well-developed fishhook-shaped accessory bodies. Current evidence shows that ricaniid species have D-shaped mitochondrial derivatives in cross-section and a serrated electron-dense region. The phylogenetic relationship of Fulgoroidea with other superfamilies in Auchenorrhyncha is briefly discussed.

The effect of the sulphoxide metabolite of triclabendazole (‘Fasinex’) on the tegument of mature and immature stages of the liver fluke, Fasciola hepatica

Parasitology ◽  
1994 ◽  
Vol 108 (5) ◽  
pp. 555-567 ◽  
Author(s):  
A. W. Stitt ◽  
I. Fairweather
Keyword(s):  
Liver Fluke ◽  
Fasciola Hepatica ◽  
Ultrastructural Changes ◽  
Adult Fluke ◽  
Immature Stages ◽  
The Novel ◽  
Tissue Slices ◽  
Transmission Electron ◽  
Time Periods

SummaryThe effects of the novel benzimidazole, triclabendazole (TCBZ) (‘Fasinex’, Ciba-Geigy), in its active sulphoxide metabolite form (TCBZ-SX), on the tegumental ultrastructure of Fasciola hepatica were determined in vitro by transmission electron microscopy (TEM), using both intact flukes and tissue-slice material. At a concentration of 15 µ/ml, the tegument of the whole adult fluke showed ultrastructural changes only after prolonged time-periods, with vacuolation at the base of the syncytium and accumulation of T2 secretory bodies in the tegumental cells. At a concentration of 50 µ/ml, with both whole flukes and tissue-slices, the tegument appeared extremely abnormal with accumulation of secretory bodies towards the base of the syncytium. With longer incubation times, the tegument was completely sloughed away and the tegumental cells became synthetically inactive. The tegument of the 3-week-old juvenile became progressively convoluted at the apex, while in the basal regions there was severe vacuolation. In the tegumental cells, there were accumulations of T1 secretory bodies. These results confirm TCBZ as a potent fasciolicide, being very effective in disrupting the fluke tegument. They may go some way to explain the mode of action of this important fasciolicide.

A transmission electron microscope study on the route of entry of triclabendazole into the liver fluke,Fasciola hepatica

Parasitology ◽  
2009 ◽  
Vol 137 (5) ◽  
pp. 855-870 ◽  
Author(s):  
E. TONER ◽  
G. P. BRENNAN ◽  
F. McCONVERY ◽  
M. MEANEY ◽  
I. FAIRWEATHER
Keyword(s):  
Liver Fluke ◽  
Marked Decrease ◽  
Fasciola Hepatica ◽  
Oral Route ◽  
Drug Uptake ◽  
Oral Uptake ◽  
Transmission Electron ◽  
Pharmacological Studies ◽  
Transmission Electron Microscope Study

SUMMARYUptake of triclabendazole by the liver fluke,Fasciola hepaticahas been studied by experiments designed to block either oral uptake of drug, by use of ligatures, or trans-tegumental diffusion, by allowing the drug to bind to an excess of bovine serum albumin (BSA) in the medium. Changes to the tegumental system, musculature and gut were assessed using transmission electron microscopy. Flukes were incubatedin vitrofor 24 h in TCBZ.SO (15 μg/ml). Disruption to the tegument and muscle was similar in ligatured and non-ligatured flukes, suggesting that closing the oral route did not affect drug uptake. The ultrastructure of the gastrodermal cells remained unchanged. Non-ligatured flukes were also incubated for 24 hin vitroin TCBZ.SO (15 μg/ml) in the presence of red blood cells (RBCs). Oral uptake of blood was demonstrated, but gut ultrastructure remained normal, whereas the tegument was severely disrupted. In separate experiments, ligatured and non-ligatured flukes were incubated in TCBZ.SO (15 μg/ml) in the presence of BSA (30 mg/ml) for 24 hin vitro. There was a marked decrease in the degree of tegumental disruption observed compared with TCBZ.SO action alone; again, the gut remained normal. The findings support previous morphological and pharmacological studies indicating that trans-tegumental uptake of triclabendazole predominates in the liver fluke.

Physiological and morphological effects of genistein against the liver fluke, Fasciola hepatica

Parasitology ◽  
2008 ◽  
Vol 135 (10) ◽  
pp. 1189-1203 ◽  
Author(s):  
E. TONER ◽  
G. P. BRENNAN ◽  
K. WELLS ◽  
J. G. McGEOWN ◽  
I. FAIRWEATHER
Keyword(s):  
Structural Changes ◽  
Liver Fluke ◽  
Fasciola Hepatica ◽  
Somatic Muscle ◽  
Shell Protein ◽  
Transmission Electron ◽  
Short Time Span ◽  
Vitelline Cells ◽  
Short Time

SUMMARYA study has been carried out to determine the activity of genistein against adult liver fluke, Fasciola hepatica. Flukes were incubated in vitro in genistein at a concentration of 0·27 mg/ml (=1 mm). They ceased to move after 3 h, at which point the experiment was terminated and the specimens prepared for examination by scanning and transmission electron microscopy. Surface changes to the flukes comprised swelling and blebbing, especially in the posterior region of the flukes, and there was particular disruption to the spines, accompanied by some spine loss. Fine structural changes to the tegumental syncytium indicated an accelerated release of secretory bodies at the surface, but a reduction in their production within the cell bodies. Autophagic activity was evident in the tegumental cells, a phenomenon that was also observed in the gastrodermal cells. Disruption to the testis and vitelline follicles was severe, with an apparent block in the normal developmental sequence of the spermatogenic and vitelline cells, respectively. Shell protein production by the vitelline cells was also disrupted. In separate experiments, somatic muscle strips were exposed to concentrations of genistein ranging from 1 μm to 1 mm. There were statistically significant increases in the frequency and/or amplitude of muscle contractions at concentrations of 10 μm, 100 μm and 1 mm. The results suggest that genistein is capable of causing severe morphological and neuromuscular disruption to adult flukes in vitro over a short time-span.

Adult triclabendazole-resistantFasciola hepatica: morphological changes in the tegument and gut followingin vivotreatment with artemether in the rat model

2009 ◽  
Vol 83 (2) ◽  
pp. 151-163 ◽  
Author(s):  
J.F. O'Neill ◽  
R.C. Johnston ◽  
L. Halferty ◽  
G.P. Brennan ◽  
J. Keiser ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Structural Changes ◽  
Liver Fluke ◽  
Fasciola Hepatica ◽  
Morphological Changes ◽  
Oral Route ◽  
Normal Morphology ◽  
Transmission Electron ◽  
Large Numbers

AbstractA study has been carried out to determine the morphological changes to the adult liver fluke,Fasciola hepaticaafter treatmentin vivowith artemether. Rats were infected with the triclabendazole-resistant Sligo isolate ofF. hepatica, dosed orally with artemether at a concentration of 200 mg/kg and flukes recovered at 24, 48 and 72 h post-treatment (p.t.). Surface changes were monitored by scanning electron microscopy and fine structural changes to the tegument and gut by transmission electron microscopy. Twenty-four hours p.t., the external surface showed minor disruption, in the form of mild swelling of the tegument. The tegumental syncytium and sub-tegumental tissues appeared relatively normal. Forty-eight and seventy-two hours p.t., disruption to the tegumental system increased, with isolated patches of surface blebbing and reduced production of secretory bodies by the tegumental cells being the main changes seen. The gastrodermal cells showed a relatively normal morphology 24 h p.t. By 48 h, large numbers of autophagic vacuoles and lipid droplets were present. Autophagy increased in magnitude by 72 h p.t. and substantial disruption to the granular endoplasmic reticulum was observed. Results from this study show that flukes treatedin vivowith artemether display progressive and time-dependent alterations to the tegument and gut. Disruption to the gut was consistently and substantially more severe than that to the tegument, suggesting that an oral route of uptake for this compound predominates. This is the first study providing ultrastructural information on the effect of an artemisinin compound against liver fluke.

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