Comparative ultrastructure of the spermatozoa of Inermicapsifer guineensis and Inermicapsifer madagascariensis (Cestoda, Anoplocephalidae, Inermicapsiferinae), intestinal parasites of rodents in Senegal

1994 ◽  
Vol 72 (9) ◽  
pp. 1633-1638 ◽  
Author(s):  
Cheikh Tidiane Bâ ◽  
Bernard Marchand
Keyword(s):  
Anterior Extremity ◽  
Posterior Extremity ◽  
Intestinal Parasites ◽  
Sperm Nucleus ◽  
Dense Material ◽  
Cortical Microtubules ◽  
Electron Dense Material ◽  
Apical Cone ◽  
Comparative Ultrastructure ◽  
Electron Lucent

Spermatozoa of Inermicapsifer guineensis and Inermicapsifer madagascariensis are filiform and tapered at both extremities. The anterior extremity exhibits an apical cone of electron-dense material and two helical ridges. The axoneme, of the 9 + "1" pattern, is surrounded over part of its length by a sheath of electron-dense material. At the posterior extremity the cytoplasm contains electron-dense material. In regions III and IV of the spermatozoa the cytoplasm is subdivided into compartments of electron-lucent material limited by irregularly spaced walls of electron-dense material. The sperm nucleus is a compact cord wound in a spiral around the axoneme. Cortical microtubules are helically arranged down the length of the spermatozoa except at the posterior extremity where they run parallel to the spermatozoon axis. In I. madagascariensis, cortical microtubules may not extend as far as the posterior extremity of the spermatozoa; the dense periaxonemal material exists in regions I to IV of the spermatozoon and the nucleus never coils more than once around the axoneme.

Spermiogenesis and spermatozoon of the tapeworm Parabothriocephalus gracilis (Bothriocephalidea): Ultrastructural and cytochemical studies

2010 ◽  
Vol 55 (1) ◽  
Author(s):  
Lenka Šípková ◽  
Céline Levron ◽  
Mark Freeman ◽  
Tomáš Scholz
Keyword(s):  
Electron Microscopy ◽  
Anterior Extremity ◽  
Mature Spermatozoon ◽  
Dense Material ◽  
Apical Region ◽  
Cortical Microtubules ◽  
Electron Dense Material ◽  
Dense Granules ◽  
Cytoplasmic Extension ◽  
Transmission Electron

AbstractSpermiogenesis and spermatozoon ultrastructure of the tapeworm Parabothriocephalus gracilis were described using transmission electron microscopy (TEM). Spermiogenesis is characterized by the formation of a zone of differentiation with two centrioles associated with striated rootlets, and an intercentriolar body between them. The two flagella undergo a rotation of 90° until they become parallel to the median cytoplasmic extension with which they fuse. Electron-dense material is present in the apical region of the zone of differentiation in the early stages of spermiogenesis. This electron-dense material is characteristic for the orders Bothriocephalidea and Diphyllobothriidea. The mature spermatozoon contains two axonemes of the 9 + ‘1’ trepaxonematan pattern, nucleus, parallel cortical microtubules and electron-dense granules of glycogen. The anterior extremity of the spermatozoon exhibits a single helical electron-dense crested body 130 nm thick. One of the most interesting features is the presence of a ring of cortical microtubules surrounding the axoneme. This character has been reported only for species of the order Bothriocephalidea and may be unique in this cestode group.

Spore wall ultrastructure in the liverwort Fossombronia longiseta

1984 ◽  
Vol 62 (9) ◽  
pp. 1871-1879 ◽  
Author(s):  
M. P. Steinkamp ◽  
W. T. Doyle
Keyword(s):  
Spore Wall ◽  
Dense Material ◽  
White Line ◽  
Electron Dense Material ◽  
Transmission Electron ◽  
Wall Ultrastructure ◽  
Electron Microscopes ◽  
Electron Lucent

Mature spores of Fossombronia longiseta (Metzgeriales, Codoniaceae) were examined with both scanning and transmission electron microscopes. Sporoderms are highly sculptured. The distal face markings consist of parallel ridges (cristae) or spines. The flattened proximal face has a series of short spinelike cristae, and a triradiate ridge mark sometimes is apparent. In section, the sporoderm consists of an intine and a two-layered exine. The inner exine layer consists of two lamellae, each of which contains a series of long, thin (3–4 nm), closely spaced, electron-lucent subunits; the subunits are separated by electron-dense material. The more or less solid outer exine consists of highly irregularly shaped lamellae, which also have a "white line" component. Amorphous, electron-dense material permeates these lamellae and fills the channels between the lamellae. The intine and much of the electron-dense material of the exine is removed by acetolysis. Spore wall ultrastructure in this species is complex compared with other species of the Metzgeriales and Jungermanniales that have been studied so far.

scholarly journals Ultrastructure of mature spermatozoa of three Bucephalidae (Prosorhynchus longisaccatus, Rhipidocotyle khalili and Bucephalus margaritae) and phylogenetic implications

Parasite ◽  
2018 ◽  
Vol 25 ◽  
pp. 65 ◽  
Author(s):  
Papa Ibnou Ndiaye ◽  
Bernard Marchand ◽  
Cheikh Tidiane Bâ ◽  
Jean-Lou Justine ◽  
Rodney A. Bray ◽  
...  
Keyword(s):  
Plasma Membrane ◽  
Anterior Extremity ◽  
Posterior Extremity ◽  
Anterior Part ◽  
Mature Spermatozoon ◽  
Cortical Microtubules ◽  
Lateral Expansion ◽  
Phylogenetic Implications ◽  
External Ornamentation ◽  
Mature Spermatozoa

We describe here the mature spermatozoa of three species of bucephalids, namely Bucephalus margaritae, Rhipidocotyle khalili and Prosorhynchus longisaccatus. This study provides the first ultrastructural data on the genera Bucephalus and Rhipidocotyle and enabled us to confirm the model of the mature spermatozoon in the Bucephalinae. The spermatozoon exhibits two axonemes with the 9 + “1” pattern of the Trepaxonemata, one of which is very short, lateral expansion, external ornamentation of the plasma membrane located in the anterior extremity of the spermatozoon and associated with cortical microtubules, spine-like bodies, a mitochondrion, and a nucleus. The maximum number of cortical microtubules is located in the anterior part of the spermatozoon. However, more studies are needed to elucidate if spine-like bodies are present in all the Bucephalinae or not. In the Prosorhynchinae, the mature spermatozoon exhibits a similar ultrastructural pattern. Some differences are observed, particularly the axoneme lengths and the arrangement of the spine-like bodies. The posterior extremity of the spermatozoon in the Bucephalinae exhibits only the nucleus, but prosorhynchines have microtubules.

scholarly journals Ultrastructure of the cirrus sac of the male strobila of Shipleya inermis (Fuhrmann, 1908) (Cestoda: Cyclophyllidea)

2011 ◽  
Vol 48 (3) ◽  
pp. 174-183 ◽  
Author(s):  
L. Poddubnaya ◽  
N. Pospekhova
Keyword(s):  
Secretory Granules ◽  
Ejaculatory Duct ◽  
Muscle Layer ◽  
Dense Material ◽  
Electron Dense Material ◽  
Peripheral Muscle ◽  
Lateral Margins ◽  
Limnodromus Scolopaceus ◽  
Longitudinal Muscles ◽  
Electron Lucent

AbstractThis study was designed to provide information on the ultrastructural traits of the cirrus sac of the male strobila of the dioecious cyclophyllidean tapeworm, Shipleya inermis Fuhrmann, 1908 from the small intestine of long-billed dowitchers, Limnodromus scolopaceus, in Chukotka, Russia. The cirrus sac is characterised by a thick muscular wall (comprising about 20 layers of longitudinal muscles) with the muscle cells being located outside the wall along the peripheral muscle layer and the presence of a thick, fibrillar septum inside the sac along the inner muscle layer of the wall. The epithelium of the intrabursal ducts is syncytial and has sunken perikarya. The ejaculatory duct is characterised by surface luminal microvilli and a large number of the sunken perikarya producing electron-dense secretory granules, which discharge into the duct lumen as an apocrine secretion. The cirrus is armed with two types of sclerotized structures formed by its epithelium, hooks of about 25 μm in length and microthrix-like structures on its luminal surface. The hooks are sigmoid in shape, have a blade circular in transverse section and about 3.5 μm in width, and taper at both extremities. The hook body consists of moderately electron-dense material mixed with a more electron-dense material and an electron-lucent core. The hook roots lie within the cirrus epithelium, where their lateral margins are composed of a thin covering of electrondense material with narrow lateral extensions. The usefulness of the ultrastructural characters of the cirrus sac as indicators of phylogenetic relationships within the Eucestoda is discussed.

Ultrastructural study of spermiogenesis and the spermatozoon in Catenotaenia pusilla, an intestinal parasite of Mus musculus

2000 ◽  
Vol 74 (1) ◽  
pp. 73-81 ◽  
Author(s):  
C. Hidalgo ◽  
J. Miquel ◽  
J. Torres ◽  
B. Marchand
Keyword(s):  
Cross Section ◽  
Anterior Extremity ◽  
Intestinal Parasite ◽  
Mature Spermatozoon ◽  
Cortical Microtubules ◽  
Spiral Pattern ◽  
Cytoplasmic Extension ◽  
Apical Cone ◽  
Flagellar Rotation ◽  
Unequal Length

AbstractThe ultrastructure of spermiogenesis and the mature spermatozoon in Catenotaenia pusilla (Cestoda: Catenotaeniidae) is described. Spermiogenesis is characterized by the presence of a single axoneme which grows on the outside of a cytoplasmic extension at an angle of 45°. Flagellar rotation and proximodistal fusion are produced in this process. The centrioles lack striated roots and an intercentriolar body. In the mature spermatozoon four different regions are described. The anterior extremity is capped by an apical cone and presents two helical crest-like bodies of unequal length. The axoneme, of the 9 + ‘1’ pattern of the Trepaxonemata, presents a periaxonemal sheath. The cortical microtubules form a spiral pattern at an angle of about 40° to the hypothetical spermatozoon axis. The nucleus is kidney- to horseshoe-shaped in cross section. Granules and proteinaceus walls are not observed in the spermatozoon of C. pusilla.

scholarly journals The Ultrastructure of the Epicuticular Interference Reflectors of Tiger Beetles (Cicindela)

1985 ◽  
Vol 117 (1) ◽  
pp. 87-110
Author(s):  
T.D. SCHULTZ ◽  
M.A. RANKIN
Keyword(s):  
Refractive Index ◽  
Dense Material ◽  
Dense Layer ◽  
Surface Reflectance ◽  
Structural Coloration ◽  
Electron Dense Material ◽  
Tiger Beetles ◽  
Electron Lucent

Tiger beetles of the genus Cicindela exhibit iridescent structural coloration due to the presence of a non-ideal multilayer interference reflector located in the outermost 2 μm of the integument. The reflector is composed of alternating layers of electron-lucent and electron-dense material. This series of layers was distinguished from chitinous procuticle by its position, ultrastructure and solubility in dilute KOH. The reflector appears homologous with the inner epicuticle of current models. Measurements of surface reflectance, refractive index and the dimensions of the alternating layers suggests that the dense layer has a refractive index (RI) near 2.0 and may be a melanoprotein.

A fine structural study on the merozoite of Eimeria tenella with special reference to the conoid apparatus

Parasitology ◽  
1968 ◽  
Vol 58 (3) ◽  
pp. 561-571 ◽  
Author(s):  
Diane J. Mclaren ◽  
G. E. Paget
Keyword(s):  
Anterior Extremity ◽  
Research Laboratory ◽  
First Generation ◽  
Technical Assistance ◽  
Posterior Extremity ◽  
Eimeria Tenella ◽  
Main Body ◽  
Electron Dense Material ◽  
Double Membrane ◽  
Veterinary Research

The ultrastructure of the merozoite of Eimeria tenella has been studied by means of electron microscopy. The first-generation merozoite is approximately 3·4 μm in length, and 1·2 μm in width, while the second-generation merozoite is approximately 10·5 μm in length and 1·5 μm in width.The cell wall of the merozoite consists of a double membrane, but at the anterior extremity the existence of a fluted collar gives the appearance of two narrow double membranes separated by a zone of less electron-dense material. Twenty-four surface fibrils are distributed around the periphery; they extend along the entire length of the organism and lie beneath the double limiting membrane.The anterior end of the merozoite is distinguished by a conoid apparatus which includes several components. A bulbiform outer annulus is invested by a fluted collar, and itself encloses an extrusible papilla. Two osmiophilic fibrils, the paired organelles, arise within the extrusible papilla and extend longitudinally into the cytoplasm. Twenty-four smaller fibrils, or toxonemes, also arise within the conoid and pass back into the main body of the organism.The cytoplasm of the merozoite includes mitochondria, glycogen, dense elliptical granules and endoplasmic reticulum, together with a definite Golgi complex. A nucleus is located in the posterior third of the organism and is enclosed by a perforated double membrane. At the posterior extremity the double membrane which bounds the organism is broken by a pore 700 A in diameter.Our sincere thanks are due to Mr P. Richmond for technical assistance, and we are grateful to the Central Veterinary Research Laboratory, Weybridge, for supplying the strain of Eimeria tenella.

The ultrastructure of the pseudohaptoral squamodiscs of Diplectanum aequans (Monogenea)

Parasitology ◽  
1981 ◽  
Vol 82 (2) ◽  
pp. 231-240 ◽  
Author(s):  
M. K. Shaw
Keyword(s):  
Dense Material ◽  
Prominent Feature ◽  
Electron Dense Material ◽  
Dense Membrane ◽  
Membrane Bound ◽  
Epidermal Membrane ◽  
Electron Lucent

SUMMARYThe ultrastructure of the pseudohaptoral squamodiscs of the monogenean Diplectanum aequans is described. The most prominent feature of the squamodisc is the presence of epidermally-embedded spines which are covered by the outer epidermal membrane. These spines, which are ‘hollow’, are composed of a moderately electron-dense material with denser fibrils embedded within it. The squamodisc epidermis is similar in appearance to the haptor epidermis, with the exception of the epidermis ‘inside’ the spines. Here the epidermis contains free ribosomes and stacks of alternating electron-lucent/electron-dense, membrane-bound sacs. The arrangement of the musculature of the spines is described. The free, prehensile, edges of the squamodiscs contain numerous radially orientated nerves, some of which are assumed to be mechano-receptors.

Comparative Morphology of Intercellular Bridges Between Developing Germ Cells of the Ovary

1970 ◽  
Vol 28 ◽  
pp. 328-329
Author(s):  
J. R. Ruby ◽  
R. F. Dyer ◽  
R. G. Skalko ◽  
R. F. Gasser ◽  
E. P. Volpe
Keyword(s):  
Germ Cells ◽  
Rana Pipiens ◽  
Comparative Morphology ◽  
Dense Material ◽  
Individual Species ◽  
Microscope Examination ◽  
Electron Dense Material ◽  
Intercellular Bridges ◽  
Cytoplasmic Side ◽  
Intercellular Connections

An electron microscope examination of fetal ovaries has revealed that developing germ cells are connected by intercellular bridges. In this investigation several species have been studied including human, mouse, chicken, and tadpole (Rana pipiens). These studies demonstrate that intercellular connections are similar in morphology regardless of the species.Basically, all bridges are characterized by a band of electron-dense material on the cytoplasmic side of the tri-laminar membrane surrounding the connection (Fig.l). This membrane is continuous with the plasma membrane of the conjoined cells. The dense material, however, never extends beyond the limits of the bridge. Variations in the configuration of intercellular connections were noted in all ovaries studied. However, the bridges in each individual species usually exhibits one structural characteristic seldom found in the others. For example, bridges in the human ovary very often have large blebs projecting from the lateral borders whereas the sides of the connections in the mouse gonad merely demonstrate a slight convexity.

The ultrastructure of M1-a-mediated resistance to powdery mildew infection in barley

1975 ◽  
Vol 53 (22) ◽  
pp. 2589-2597 ◽  
Author(s):  
H. H. Edwards
Keyword(s):  
Powdery Mildew ◽  
Host Cell ◽  
Electron Density ◽  
Epidermal Cells ◽  
Dense Material ◽  
Ultrastructural Changes ◽  
Electron Dense Material ◽  
Host Cytoplasm ◽  
Powdery Mildew Infection ◽  
Cell Protoplast

M1-a-mediated resistance in barley to invasion by the CR3 race of Erysiphe graminis f. sp. hordei does not occur in every host cell with the same speed and severity. In some cells ultrastructural changes within the host cell as a result of resistance will occur within 24 h after inoculation, whereas in other cells these changes may take up to 72 h. In some cells the ultrastructural changes are so drastic that they give the appearance of a hypersensitive death of the host cell, whereas in other cells the changes are very slight. In any case, at the end of these changes the fungus ceases growth. The ultrastructural changes occur in penetrated host epidermal cells as well as non-infected adjacent epidermal and mesophyll cells.The following ultrastructural changes have been observed: (1) an electron-dense material which occurs either free in the vacuole or adhering to the tonoplast (the material is granular or in large clumps); (2) an increased electron density of the host cytoplasm and nucleus; (3) a breakdown of the tonoplast so that the cytoplasmic constituents become dispersed throughout the cell lumen; and (4) the deposition of papillar-like material in areas other than the penetration site. The first three changes take place within the host cell protoplasts and are directly attributable to the gene M1-a. These changes are typical of stress or incompatibility responses and thus M1-a appears to trigger a generalized incompatibility response in the presence of race CR3. The papillar-like material occurs outside the host cell protoplast in the same manner as the papilla and probably is not directly attributable to M1-a.

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