Structure and evolution of the pharynx in the Temnocephalida (Platyhelminthes)

1997 ◽  
Vol 75 (2) ◽  
pp. 205-226 ◽  
Author(s):  
Boris I. Joffe ◽  
Irina V. Solovei ◽  
Nikki A. Watson ◽  
Lester R. G. Cannon
Keyword(s):  
Anterior Margin ◽  
Specific Pattern ◽  
Muscle Fibres ◽  
Sensory Receptors ◽  
Transmission Electron ◽  
Silver Nitrate Staining ◽  
Pharyngeal Epithelium ◽  
Data Evolution ◽  
Pharyngeal Musculature

The structure of the pharynx was studied in the genera Didymorchis, Diceratocephala, Temnocephala, and Craspedella, using light microscopy, silver nitrate staining, and transmission electron microscopy. Based on these data, evolution of this organ within the Temnocephalida is analysed. In addition to the specific pattern of muscle fibres in the walls of the pharynx known from earlier studies, three other features characteristic of the pharynges of temnocephalids were found: (1) multisyncytial organization of the pharyngeal epithelium, (2) the presence of type 1 sensory receptors, and (3) muscle fibres incorporated into the epithelium of the pharynx. Features deduced to be characteristic of the pharynx in primitive temnocephalids are (i) the presence of three types of sensory receptors with specific morphologies and locations in the pharynx, (ii) the presence of a bundle of muscle fibres that traverses the epithelium surrounding the anterior margin of the pharynx, (iii) characteristic lamellation of the epithelium of the pharynx proper, and (iv) a narrow syncytium nesting the openings of the pharyngeal glands and forming deep invaginations into which the gland ducts open. The most prominent tendencies in the evolution of the pharynx are reinforcement of the pharyngeal musculature (related to the mode of feeding) and reduction in the number of syncytia.

Topography and ultrastructure of the tegument of Aphallus tubarium (Rodolphi, 1819) Poche, 1926 (Digenea: Cryptogonimidae), intestinal parasite of the common Dentex dentex (Linnaeus 1758) from Valinco Gulf

2014 ◽  
Vol 59 (4) ◽  
Author(s):  
Laetitia Antonelli ◽  
Yann Quilichini ◽  
Joséphine Foata ◽  
Bernard Marchand
Keyword(s):  
Anterior Part ◽  
Posterior Part ◽  
Sensory Receptors ◽  
Apical Seta ◽  
Transmission Electron ◽  
Dentex Dentex ◽  
Sensory Structures ◽  
First Time

AbstractThe tegument ultrastructure of the intestinal fluke Aphallus tubarium was studied for the first time with the use of scanning and transmission electron microscopy. New details on morphology were recorded. The ultrastructural study revealed that the tegument of A. tubarium had a syncytial organization with a distal cytoplasm lying over a basal matrix and cytons. The surface of the tegument is covered with pectinate spines arranged quincuncially. As anterior-posterior differences were observed, particular attention was given to spines. Spines decrease in size and density from the anterior part of body to posterior part. Two types of sensory structures were identified, uniciliated and dome-shaped. Type 1 sensory receptors were outgrowths bearing groups of papillae with shorter and rigid apical seta visible on the anterior part of body surface, encircling the worm. Type 2 sensory receptors was dome-shaped papillae devoid of cilia, found mainly around the oral sucker. Diagrams of spines and sensory receptors were made to help in understanding the nature of these structures. Surface morphology may prove to be useful in distinguishing Aphallus spp with other Cryptogonimidae.

Comparative Study of the Fine Morphology of Sensory Receptors in Aspidogaster conchicola and Cotylaspis insignis

1972 ◽  
Vol 30 ◽  
pp. 150-151
Author(s):  
Venita F. Allison ◽  
J. E. Ubelaker ◽  
J. H. Martin
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Nervous System ◽  
Osmic Acid ◽  
Sensory Receptors ◽  
Transmission Electron ◽  
Sensory Structures ◽  
Fine Morphology ◽  
Scanning Electron

It has been suggested that parasitism results in a reduction of sensory structures which concomitantly reflects a reduction in the complexity of the nervous system. The present study tests this hypothesis by examining the fine morphology and the distribution of sensory receptors for two species of aspidogastrid trematodes by transmission and scanning electron microscopy. The species chosen are an ectoparasite, Cotylaspis insignis and an endoparasite, Aspidogaster conchicola.Aspidogaster conchicola and Cotylaspis insignis were obtained from natural infections of clams, Anodonta corpulenta and Proptera purpurata. The specimens were fixed for transmission electron microscopy in phosphate buffered paraformaldehyde followed by osmic acid in the same buffer, dehydrated in an ascending series of ethanol solutions and embedded in Epon 812.

The ultrastructure of the epidermis of the redia and cercaria of Parorchis acanthus, Nicoll. A study by scanning and transmission electron-microscopy

Parasitology ◽  
1971 ◽  
Vol 62 (3) ◽  
pp. 479-488 ◽  
Author(s):  
Gwendolen Rees
Keyword(s):  
Electron Micrographs ◽  
Technical Assistance ◽  
Ventral Surface ◽  
The Body ◽  
Muscle Fibres ◽  
Scanning Electron Micrographs ◽  
Large Area ◽  
Transmission Electron ◽  
Parorchis Acanthus ◽  
Scanning Electron

Scanning electron-micrographs have shown the covering of microvilli on the surface of the redia of Parorchis acanthus. In the contracted state the elongated microvilli with bulbous extremities seen in the surface grooves may be the result of compression. The surface of the epidermis of the cercaria is smooth on a large area of the ventral surface and lattice-like with microvilli, laterally, anteriorly, dorsally and on the tail. The spines on the body can be withdrawn into sheaths by the contraction of muscle fibres inserted into the basement lamina below each spine.I would like to express my sincere gratitude to Dr I. ap Gwynn of this department for preparing the scanning electron-micrographs and the School of Engineering Science, University of North Wales, Bangor for the use of their stereoscan. I should also like to thank Mr M. C. Bibby for technical assistance and Professor E. G. Gray and Dr W. Sinclair for assistance with the transmission electron-micrographs.

The Macropodid Oesophagus I. Gross Anatomical, Light Microscopic, Scanning and Transmission Electron Microscopic Observations of its Mucosa

1984 ◽  
Vol 32 (4) ◽  
pp. 415 ◽  
Author(s):  
DL Obendorf
Keyword(s):  
Electron Microscopic ◽  
Dietary Preferences ◽  
Type Iv ◽  
Transmission Electron ◽  
Transmission Electron Microscopic ◽  
Wallabia Bicolor ◽  
Phylogenetic Associations

The results of examinations on the oesophagus of 248 animals of 36 species of macropodid marsupials are presented in this paper. Four distinct morphological types of oesophageal lining are described and the species examined classified accordingly. The oesophagus of Aepyprymnus: Bettongia, Dendrolagus, Hypsiprymnodon, Onychogalea; Petrogale; Peradorcas, Setonix and Thylogale has a smooth lining with small and simple longitudinal folds (type 1). The large kangaroos of the genus Macropus (M. antilopinus. M. bernardus, M. fuliginosus, M. giganteus. M. robustus, and M. rufus) have smooth oesophageal linings with extensively pleated longitudinal folds (type 11). The so-called brush wallabies of the genus Macropus (M. agilis, M. dorsalis, M. eugenii, M. irma; M. parma and M. parryi) and Wallabia bicolor have papillated oesophageal linings (type 111). In the red-necked wallaby M. rufogriseus banksianus and the Bennett's wallaby M. r. rufogriseus the oesophagus proximal to the diaphragm is lined with longitudinal leaf-like, laminar plates. and distal to the diaphragm the lining consists of finger-like papillae (type IV). The morphology of the oesophagus in the various macropodid species is discussed in relation to dietary preferences, habitat. and phylogenetic associations between species.

Cellular patterning of fast and slow fibres in the intermandibularis muscle of chick embryos

Development ◽  
1993 ◽  
Vol 117 (1) ◽  
pp. 329-339 ◽  
Author(s):  
L.G. Robson
Keyword(s):  
Cell Types ◽  
Specific Pattern ◽  
Slow Muscle ◽  
Limb Bud ◽  
Muscle Fibres ◽  
Chick Embryos ◽  
Myogenic Cells ◽  
Lower Jaw ◽  
Cellular Pattern

The way in which the pattern of cell types arises during development of individual muscles was explored. The pattern of cellular differentiation resulting from the synthesis of particular fast and slow myosin heavy chains (MyHC) was investigated in the intermandibularis muscle in the lower jaw of chick embryos. The intermandibularis muscle has a proximodistal pattern of fibre type distribution. The distal region of the muscle contains a ratio of 1.5:1 fast to slow muscle fibres, which increases to > 2.5:1 in the proximal region. The intermandibularis muscle is assembled in a proximodistal sequence, with both fast and slow muscle cells differentiating within the earliest muscle and then establishing the specific pattern of cell types. This pattern is not dependent on a specific innervation source, as normal lower jaw muscles develop and the intermandibularis has the same graded cellular pattern when the mandibular primordium is grafted to the limb bud stump. Micromass cultures were used to explore the pool of potentially myogenic cells that are available to construct the muscles. Even before the muscle differentiates in vivo, both fast and slow cells are present in the primordia. These potentially myogenic cells are already distributed within the primordium in a proximodistal fashion that mimics the cellular pattern found in the muscle that develops.

scholarly journals Angiopoietin-1 Promotes the Integrity of Neovascularization in the Subcutaneous Matrigel of Type 1 Diabetic Rats

2019 ◽  
Vol 2019 ◽  
pp. 1-11 ◽  
Author(s):  
ShaoBin LI ◽  
HeQin Zou ◽  
MinMin Gong ◽  
YuQin Chen ◽  
XiaoYong Yan ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Treatment Group ◽  
Abdominal Cavity ◽  
Vascular Endothelial Cell ◽  
Diabetic Rats ◽  
Vascular Endothelial ◽  
Transmission Electron ◽  
Junction Protein

Objective. This study aimed to investigate the effects of Ang-1 on neovascularization of diabetic organs by subcutaneous Matrigel angiogenesis model, established in type 1 diabetic rats. Methods. Ang-1 adenoviral vector was constructed. The rat model was established by STZ and divided into four group. The Matrigel was inserted subcutaneously into the abdominal cavity of rats at 8 weeks, the treatment group was injected with Ang-1 adenovirus vector via tail vein, and the rats were sacrificed at 10 weeks. Neovascularization of Matrigel was observed with transmission electron microscopy. The marker of vascular endothelial cell and pericyte were detected by immunofluorescence. Immunohistochemical detection of the neovascular endothelial junction protein was performed. RT-PCR was used to determine protein expression of neovascular in Matrigel. Results. Vascular cavity-like structure could be seen in subcutaneous Matrigel of diabetic rats, and the cavity was filled with a lot of red blood cells. Transmission electron microscopy showed that neovascular endothelial structure of the Matrigel was incomplete, while the Ang-1 treatment group had more vascular cavity-like structures, intact vascular endothelial structure, and reduced inflammatory cell infiltration in Matrigel. Additionally, the integrity of vascularization improved, and the marker of pericyte and the cell tight junctions protein was upregulated in Ang-1 treatment group. Conclusion. Hyperglycemia could induce pathological angiogenesis in subcutaneous Matrigel of diabetic rats, and Ang-1 could upregulate the expression of intercellular junction protein in subcutaneous Matrigel of diabetic rats and promote the integrity of neovascularization in the subcutaneous Matrigel of diabetic rats.

scholarly journals Thickening of T1 Precipitates during Aging of a High Purity Al–4Cu–1Li–0.25Mn Alloy

Materials ◽  
2018 ◽  
Vol 12 (1) ◽  
pp. 30 ◽  
Author(s):  
Ines Häusler ◽  
Reza Kamachali ◽  
Walid Hetaba ◽  
Birgit Skrotzki
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
High Purity ◽  
External Load ◽  
Volume Fraction ◽  
Single Layer ◽  
Age Hardening ◽  
Defect Type ◽  
Transmission Electron

The age hardening response of a high-purity Al–4Cu–1Li–0.25Mn alloy (wt. %) during isothermal aging without and with an applied external load was investigated. Plate shaped nanometer size T1 (Al2CuLi) and θ′ (Al2Cu) hardening phases were formed. The precipitates were analyzed with respect to the development of their structure, size, number density, volume fraction and associated transformation strains by conducting transmission electron microscopy (TEM) and scanning transmission electron microscopy (STEM) studies in combination with geometrical phase analysis (GPA). Special attention was paid to the thickening of T1 phase. Two elementary types of single-layer T1 precipitate, one with a Li-rich (Type 1) and another with an Al-rich (Defect Type 1) central layer, were identified. The results show that the Defect Type 1 structure can act as a precursor for the Type 1 structure. The thickening of T1 precipitates occurs by alternative stacking of these two elementary structures. The thickening mechanism was analyzed based on the magnitude of strain associated with the precipitation transformation normal to its habit plane. Long-term aging and aging under load resulted in thicker and structurally defected T1 precipitates. Several types of defected precipitates were characterized and discussed. For θ′ precipitates, a ledge mechanism of thickening was observed. Compared to the normal aging, an external load applied to the peak aged state leads to small variations in the average sizes and volume fractions of the precipitates.

Ultrastructure of intraocular muscles of diving and nondiving ducks

1982 ◽  
Vol 60 (7) ◽  
pp. 1588-1606 ◽  
Author(s):  
J. G. Sivak ◽  
O. E. Vrablic
Keyword(s):  
Neuromuscular Junctions ◽  
Muscle Fibres ◽  
Dark Cell ◽  
Domestic Ducks ◽  
Diving Ducks ◽  
Light Cell ◽  
Axon Terminals ◽  
End Plate ◽  
Transmission Electron ◽  
Skeletal Muscle Fibres

The fine structure of ciliary muscle (CM), iris sphincter (IS), and neuromuscular junctions (NMJ) were studied by light and transmission electron microscopy in domestic ducks (Anas platyrhynchos) and diving ducks (Mergus merganser). Previous work has shown that the iris produces exaggerated acommodative ability in the diver. Both muscles are striated in the two species. While both muscles of domestic ducks and the CM of the diving ducks consist of one cell type, the IS of the latter is made up of two types of cells referred to as "light" and "dark." The "light" cell has long, thin, uniformly distributed mitochondria, while in the "dark" cells they are large, unevenly dispersed and often aggregated subsarcolemmally. The sarcoplasmic reticulum is more abundant in both IS and CM of domestic ducks, while well developed T tubules are seen more regularly in the intraocular muscles of diving ducks.The NMJ's do not show the complexity seen in singly innervated skeletal muscle fibres. All the nerve axon terminals end in a flat shallow trough and postjunctional folds are either nonexistent or very shallow. The NMJ's of the IS of domestic ducks and of the "dark" cell of the IS of diving ducks consist of a large single end plate. That of the CM of domestic ducks consists of a diffuse single end plate while the NMJ of the CM of diving ducks consists of diffuse multiple endings. Nerve endings of similar size and structure but occurring only singly were found on the "light" cell of the IS of domestic ducks.

Hrtem Studies of Dislocations and Interfaces in TiAl

1996 ◽  
Vol 466 ◽  
Author(s):  
M. J. Mills ◽  
J. M.K. Wiezorek ◽  
H. L. Fraser
Keyword(s):  
Single Phase ◽  
Stacking Fault ◽  
Interface Plane ◽  
Two Phase ◽  
Transmission Electron ◽  
Interphase Boundaries ◽  
Common Observation ◽  
Interface Structures ◽  
Fully Lamellar

ABSTRACTIn this paper, we summarize the results of high resolution transmission electron microscopy investigations of the structure of dislocations and interphase boundaries in Ti-Al alloys. Dislocations of the type 1/2<110] and 1/2<112] have been examined in 60° and 90° orientations, respectively, in single-phase Ti-52 at%Al. The former dislocation exhibits an extremely compact core configuration, suggesting a high complex stacking fault energy, while the latter is dissociated the scale of several nanometers in a coupled intrinsic/extrinsic stacking fault configuration. Two types of α2/γ interface structures have been observed in nearly fully-lamellar Ti-48 at%Al. The first is consistent with the common observation of structural ledges due to 1/6<112> dislocations in the interface plane. The second interface type consists of a quasi-periodic array of 1/2<110] dislocations which do not lie in the interface, and appear to be contained wholy within the γ phase. The possible implications of these observations with respect to the mechanical behavior of both single-phase γ and two-phase lamellar microstructures are discussed.

Sign in / Sign up

Export Citation Format

Share Document