scholarly journals The non-brain anterior nerve center and tentacle crown structure of Owenia borealis (Annelida, Oweniidae): the evolution of the nervous system and tentacles in Bilateria

2021 ◽  
Author(s):  
Nadezhda Rimskaya-Korsakova ◽  
Vyacheslav Dyachuk ◽  
Elena Temereva
Keyword(s):  
Electron Microscopy ◽  
System Development ◽  
Sister Group ◽  
Ultrastructural Level ◽  
Myoepithelial Cells ◽  
Coelomic Cavity ◽  
Head Region ◽  
Blood Capillaries ◽  
Crown Structure ◽  
Transmission Electron

Abstract The Oweniidae are marine annelids with many unusual features of organ system, development, morphology, and ultrastructure. Together with magelionds, oweniids have been placed within the Palaeoannelida, a sister group to all remaining annelids. The study of this group may increase our understanding of the early evolution of annelids (including their radiation and diversification) and of the morphology of the last common bilaterian ancestor. In the current research, scanning electron microscopy revealed that the tentacle apparatus consists of 10 branched arms. The tentacles are covered by monociliary cells that form a ciliar groove that extends along the oral side of the arm base. Light, confocal, and transmission electron microscopy revealed that head region contains two circular intraepidermal nerves (outer and inner) that give rise to the neurites of each tentacle, i.e., intertentacular neurites are absent. Each tentacle contains a coelomic cavity with a network of blood capillaries. Monociliar myoepithelial cells of the tentacle coelomic cavity form both the longitudinal and the circular muscles. The structure of this myoepithelium is intermediate between simple and pseudo-stratified myepithelium. Overall, tentacles lack prominent zonality, i.e., co-localization of ciliary zones, neurite bundles, and muscles. This organization, which indicates a non-specialized tentacle crown in O. borealis and other oweniids with tentacles, is probably ancestral for annelids and for all Bilateria. The outer circular nerve of O. borealis is a dorsal medullary commissure that apparently functions as an anterior nerve center and is organized at the ultrastructural level as a stratified neuroepithelium. Given the hypothesis that the anterior nerve center of the last bilateral ancestor might be a diffuse neural plexus network, these results suggest that the ultra anatomy of that plexus brain might be a stratified neuroepithelium. Alternatively, the results could reflect the simplification of structure of the anterior nerve center in some bilaterian lineages.

scholarly journals “Candidatus Bacilloplasma,” a Novel Lineage of Mollicutes Associated with the Hindgut Wall of the Terrestrial Isopod Porcellio scaber (Crustacea: Isopoda)

2007 ◽  
Vol 73 (17) ◽  
pp. 5566-5573 ◽  
Author(s):  
Rok Kostanjšek ◽  
Jasna Štrus ◽  
Gorazd Avguštin
Keyword(s):  
Electron Microscopy ◽  
Sequence Similarity ◽  
Mycoplasma Hominis ◽  
Sister Group ◽  
Phylogenetic Position ◽  
Rrna Gene ◽  
Porcellio Scaber ◽  
Terrestrial Isopod ◽  
Transmission Electron ◽  
A Cell

ABSTRACT Pointed, rod-shaped bacteria colonizing the cuticular surface of the hindgut of the terrestrial isopod crustacean Porcellio scaber (Crustacea: Isopoda) were investigated by comparative 16S rRNA gene sequence analysis and electron microscopy. The results of phylogenetic analysis, and the absence of a cell wall, affiliated these bacteria with the class Mollicutes, within which they represent a novel and deeply branched lineage, sharing less than 82.6% sequence similarity to known Mollicutes. The lineage has been positioned as a sister group to the clade comprising the Spiroplasma group, the Mycoplasma pneumoniae group, and the Mycoplasma hominis group. The specific signature sequence was identified and used as a probe in in situ hybridization, which confirmed that the retrieved sequences originate from the attached rod-shaped bacteria from the hindgut of P. scaber and made it possible to detect these bacteria in their natural environment. Scanning and transmission electron microscopy revealed a spherically shaped structure at the tapered end of the rod-shaped bacteria, enabling their specific and exclusive attachment to the tip of the cuticular spines on the inner surface of the gut. Specific adaptation to the gut environment, as well as phylogenetic positioning, indicate the long-term association and probable coevolution of the bacteria and the host. Taking into account their pointed, rod-shaped morphology and their phylogenetic position, the name “Candidatus Bacilloplasma” has been proposed for this new lineage of bacteria specifically associated with the gut surface of P. scaber.

Ultrastructure of Leiomyosarcoma Invasive Phenotype

1997 ◽  
Vol 3 (S2) ◽  
pp. 19-20
Author(s):  
A. Márquez ◽  
H.J. Fino ◽  
M. Correa ◽  
P. Tonino ◽  
L. Sosa
Keyword(s):  
Electron Microscopy ◽  
Malignant Tumors ◽  
Ultrastructural Level ◽  
Electron Microscopic ◽  
Invasive Phenotype ◽  
Primary Tumors ◽  
Heterogeneous Cell Population ◽  
Metastatic Cells ◽  
Transmission Electron ◽  
Nuclear Changes

Malignant tumors are known to have an heterogeneous cell population. Metastases are supposed to be formed by subpopulations with high metastatic capability. These metastatic cells constitute the so called invasive phenotype. In that order of ideas, metastases could be pathologically different from their parent tumors if the invasive phenotype had distinct morphological features. The similarities or differences between primary tumors and their metastases have not been adequately studied at the ultrastructural level. In this work we report an electron microscopic study of liver leiomyosarcoma metastases which shows alterations not described in primary tumors of that kind.Biopsies of liver metastases from a colon leiomyosarcoma were surgically obtained. Samples were processed with routine techniques for transmission electron microscopy and observed in a Hitachi H-500 electron microscope.Some alterations usually observed in primary leiomyosarcomas were seen. They were presence of myofilaments with focal densities, nuclear changes, swollen mitochondria, and abundance of rough endoplasmic reticulum (Fig. 1).

Characterization of mammary cells from the lactating rat by electron microscopy

1978 ◽  
Vol 36 (2) ◽  
pp. 560-561
Author(s):  
P. Sadhukhan ◽  
J. Chakraborty ◽  
M. S. Soloff ◽  
M. H. Wieder ◽  
D. Senitzer
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Cell Types ◽  
Myoepithelial Cells ◽  
Mammary Tissue ◽  
Secretory Cells ◽  
Isolated Cells ◽  
Transmission Electron ◽  
Cell Processes ◽  
Phosphatase Cytochemistry

The means to identify cells isolated from the mammary gland of the lactating rat as a prerequisite for cell purification have been developed.The cells were isolated from mammary tissue with 0. 1% collagenase, and they were visualized by scanning and transmission electron microscopy and by alkaline phosphatase cytochemistry.The milk-secreting cells have surface microvilli, whereas the surface of the myoepithelial cells is smooth (Fig. 1). The two isolated epithelial cell types are readily distinguishable by transmission electron microscopy (Fig. 2). The secretory cells contain vacuoles and a relatively extensive rough endoplasmic reticulum, whereas the myoepithelial cells contain a more osmiophilic cytoplasm, contractile filaments (Fig. 3) and elongate processes. These features are consistent with the appearance of the two cell types in situ.Incubation of isolated cells with oxytocin prior to glutaraldehyde fixation resulted in the contraction of the myoepithelial cell processes (Figs. 4 & 5). This physiological response to oxytocin shows that the isolated myoepithelial cells were intact. The appearance of isolated secretory cells was unchanged by the presence of oxytocin.

scholarly journals Detailed morphology of tentacular apparatus and central nervous system in Owenia borealis (Annelida, Oweniidae)

2021 ◽  
Vol 7 (1) ◽  
Author(s):  
Elena Temereva ◽  
Nadezhda Rimskaya-Korsakova ◽  
Vyacheslav Dyachuk
Keyword(s):  
Electron Microscopy ◽  
Confocal Laser Scanning Microscopy ◽  
Laser Scanning ◽  
Nerve Ring ◽  
Laser Scanning Microscopy ◽  
Confocal Laser Scanning ◽  
Scanning Microscopy ◽  
Confocal Laser ◽  
Coelomic Cavity ◽  
Head Region

AbstractThe Oweniidae are marine annelids with many unusual features of organ system, development, morphology, and ultrastructure. Together with magelonids, oweniids have been placed within the Palaeoannelida, a sister group to all remaining annelids. The study of this group may increase our understanding of the early evolution of annelids (including their radiation and diversification). In the current research, the morphology and ulta-anatomy of the head region of Owenia borealis is studied by scanning electron microscopy (SEM), 3D reconstructions, transmission electron microscopy (TEM), and whole-mount immunostaining with confocal laser scanning microscopy. According to SEM, the tentacle apparatus consists of 8–14 branched arms, which are covered by monociliary cells that form a ciliary groove extending along the oral side of the arm base. Each tentacle contains a coelomic cavity with a network of blood capillaries. Monociliary myoepithelial cells of the tentacle coelomic cavity form both the longitudinal and the transverse muscles. The structure of this myoepithelium is intermediate between a simple and pseudo-stratified myoepithelium. Overall, tentacles lack prominent zonality, i.e., co-localization of ciliary zones, neurite bundles, and muscles. This organization, which indicates a non-specialized tentacle crown in O. borealis and other oweniids with tentacles, may be ancestral for annelids. TEM, light, and confocal laser scanning microscopy revealed that the head region contains the anterior nerve center comprising of outer and inner (=circumoral) nerve rings. Both nerve rings are organized as concentrated nerve plexus, which contains perikarya and neurites extending between basal projections of epithelial cells (radial glia). The outer nerve ring gives rise to several thick neurite bundles, which branch and extend along aboral side of each tentacle. Accordingly to their immunoreactivity, both rings of the anterior nerve center could be homologized with the dorsal roots of circumesophageal connectives of the typical annelids. Accordingly to its ultrastructure, the outer nerve ring of O. borealis and so-called brain of other oweniids can not be regarded as a typical brain, i.e. the most anterior ganglion, because it lacks ganglionic structure.

Serial Block-Face Imaging and its Potential for Reconstructing Diminutive Cell Systems: A Case Study from Arthropods

2014 ◽  
Vol 20 (3) ◽  
pp. 946-955 ◽  
Author(s):  
Elisabeth Lipke ◽  
Thomas Hörnschemeyer ◽  
Anahita Pakzad ◽  
Christopher R. Booth ◽  
Peter Michalik
Keyword(s):  
Electron Microscopy ◽  
Three Dimensional ◽  
Ultrastructural Level ◽  
Cellular Level ◽  
Cellular Systems ◽  
Transmission Electron ◽  
High Lateral Resolution ◽  
Dimensional Reconstruction ◽  
Block Face

AbstractUntil recently, three-dimensional reconstruction on an ultrastructural level was only possible using serial section transmission electron microscopy (ssTEM). However, ssTEM is highly challenging and prone to artifacts as, e.g., section loss and image distortions. New methods, such as serial block-face scanning electron microscopy (SBFSEM) overcome these limitations and promise a high lateral resolution. However, little is known about the usability of SBFSEM in diminutive, but highly complex cellular systems. We used spider sperm (~3 µm in diameter), which fulfills these conditions, to analyze the potential of SBFSEM compared with ssTEM. Our data suggest that the resolution obtained by SBFSEM allows depicting structures on a cellular level and is sufficient to discriminate subcellular components, but is highly dependent on previous staining procedures and electron density of the target structures.

Methods To Evaluate Endothelial Injury

1981 ◽  
Author(s):  
G Bondjers ◽  
G Hansson ◽  
A Bylock
Keyword(s):  
Electron Microscopy ◽  
Risk Factors ◽  
Transmission Electron Microscopy ◽  
Thymidine Incorporation ◽  
Ultrastructural Level ◽  
Endothelial Injury ◽  
Indirect Measure ◽  
Atherosclerotic Lesions ◽  
Transmission Electron ◽  
Branching Points

During the last decade the potential significance of endothelial injury for the development of atherosclerosis has been subject to an increasing interest. Thus, the effects on the arterial tissue of different types of experimental injury have been thoroughly described. Nevertheless, the hypothesis of a relationship between endothelial injury and atherosclerosis seems difficult to accept unless the effects of any of the well established risk factors for atherosclerosis can be attributed to modulations of endothelial integrity. To evaluate the presence of endothelial injury with light microscopy we have used dye exclusion tests and immunohistochemistry to detect intracellular IgG. The distribution of injured endothelium with these methods appears to be the same, and both methods are well suited for quantitative purposes. As a complement to these methods, 3H-thymidine incorporation and autoradiography may be used as an indirect measure of endothelial injury. On the ultrastructural level, scanning electron microscopy or transmission electron microscopy possibly combined with immunohistochemical techniques may be used. In our hands, however, none of these methods appear very well suited for quantitive assessment of endothelial injury. Nevertheless, dye exclusion tests, immunofluorescence, thymidine incorporation, scanning and transmission electron microscopy together constitute a reasonably complete battery of methods to evaluate the possible relationship between different risk factors and endothelial injury.Using this battery of methods we have observed an increased prevalence of endothelial injury in the vicinity of branching points as well as in the periphery of atherosclerotic lesions induced with hypercholesterolemia. Both these locations show a relationship to the formation and growth of experimental atherosclerotic lesions.

scholarly journals Morphological Characterization of Deciduous Enamel and Dentin in Patients Affected by Osteogenesis Imperfecta

2020 ◽  
Vol 10 (21) ◽  
pp. 7835
Author(s):  
Uros Josic ◽  
Tatjana Maravic ◽  
Maurizio Bossù ◽  
Milena Cadenaro ◽  
Allegra Comba ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Osteogenesis Imperfecta ◽  
Ultrastructural Level ◽  
Morphological Characterization ◽  
Deciduous Teeth ◽  
Tem Analysis ◽  
Correlative Analysis ◽  
Transmission Electron ◽  
Dentin Collagen

The purpose of this study was to clarify the structural and ultrastructural alterations of the enamel and dentin collagen network in the deciduous teeth of children affected by osteogenesis imperfecta (OI) using field-emission in-lens scanning electron microscopy (FEI-SEM) and transmission electron microscopy (TEM) analyses. Exfoliated primary teeth were collected from children with a diagnosis of OI and from healthy individuals (N = 24). Tooth slices containing both dentin and enamel were fixed, dehydrated and dried, gold sputtered, and observed using FEI-SEM. Additional dentin fragments were decalcified, dehydrated, embedded in resin, cut, and processed for TEM analysis. Under FEI-SEM, the enamel in OI-affected children showed an irregular prism distribution with the enamel hydroxyapatite crystals unpacked. Ultrastructural correlative analysis of the dentin in patients affected by OI showed an altered collagen pattern with a low density. In some areas, teeth in OI patients showed a reduction in the number of dentinal tubules, with odontoblastic process missing in most of the tubules. The presence of altered dentine and enamel organization in OI children was firmly established at an ultrastructural level, but additional biochemical studies are necessary in order to clarify quantitatively and qualitatively the collagenic and non-collagenic proteins in this disorder.

The energy filtering TEM (EFTEM) in modern biological transmisson Electron Microscopy

1995 ◽  
Vol 53 ◽  
pp. 668-669
Author(s):  
W. Probst ◽  
V.E. Bayer
Keyword(s):  
Electron Microscopy ◽  
Chemical Elements ◽  
Ultrastructural Localization ◽  
Ultrastructural Level ◽  
Limited Information ◽  
Energy Filtering ◽  
Transmission Electron ◽  
New Findings ◽  
Biochemical Analyses ◽  
Selection Of

Modern biological electron microscopy can no longer be a static tool merely describing morphology. In addition to ultrastructural information, insights into the molecular and chemical composition of a sample are needed so that new findings stemming from molecular biological and biochemical analyses can be given meaning in an ultrastructural context. Biological electron microscopy will be an essential tool for future discoveries involving the ultrastructural localization of molecules and chemical elements, and it will provide a means to identify the ultrastructural basis for a variety of reaction mechanisms. Many messenger compounds are currently known which can produce dynamic changes of either a subtle or dramatic nature at the ultrastructural level, but only the most basic of these can be examined using a conventional transmission electron microscope (CTEM). CTEMs provide limited information because they perform conventional imaging and do not employ all the signals available for analysis. Unlike a CTEM, an EFTEM permits the selection of a defined energy (wavelength) of electrons which are then used for imaging.

scholarly journals Visualizing endocytotic pathways at transmission electron microscopy via diaminobenzidine photo-oxidation by a fluorescent cell-membrane dye

2014 ◽  
Author(s):  
S. Grecchi ◽  
M. Malatesta
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Cell Membrane ◽  
Ultrastructural Level ◽  
Fluorescent Dye ◽  
Photo Oxidation ◽  
Cell Internalization ◽  
Transmission Electron ◽  
Intracellular Compartments ◽  
Suitable Technique

The endocytotic pathway involves a complex, dynamic and interacting system of intracellular compartments. PKH26 is a fluorescent dye specific for long-lasting cell membrane labelling which has been successfully used for investigating cell internalization processes, at either flow cytometry or fluorescence microscopy. In the present work, diaminobenzidine photo-oxidation was tested as a procedure to detect PKH26 dye at transmission electron microscopy. Our results demonstrated that DAB-photo-oxidation is a suitable technique to specifically visualise this fluorescent dye at the ultrastructural level: the distribution of the granular dark reaction product perfectly matches the pattern of the fluorescence staining, and the electron density of the fine precipitates makes the signal evident and precisely detectable on the different subcellular compartments involved in the plasma membrane internalization routes.

scholarly journals The sexual dimorphic inguinal glands of the frog species Ololygon centralis (Anura: Hylidae) at light and transmission electron microscopy

2019 ◽  
Vol 36 ◽  
pp. 1-9
Author(s):  
Pedro Brito ◽  
Cíntia P. Targueta ◽  
Walquíria Arruda ◽  
Fernanda Santos ◽  
Rogério Bastos
Keyword(s):  
Electron Microscopy ◽  
Microscopic Analysis ◽  
Myoepithelial Cells ◽  
Sexually Dimorphic ◽  
Pheromone Production ◽  
Similar Function ◽  
Transmission Electron ◽  
Frog Species ◽  
Different Types ◽  
Inguinal Glands

The anuran skin characteristically has different types of glands, most of which are microscopic and are spread throughout the skin. Some species have specialized regions where glands agglomerate, forming macroglands. The description of the external morphology of Ololygoncentralis (Pombal & Bastos, 1996) revealed the presence of an inguinal gland. Ololygoncentralis is the only species of the genus that has a macrogland. The present study found these inguinal macroglands to be present only on male specimens, thus characterizing it as a sexually dimorphic skin gland. Microscopic analysis revealed that these glands are composed of many syncytial units involved by myoepithelial cells. The center of the syncytium is full of a proteinaceous secretion with a basic pH and the absence of sugar residues. Similar glands observed in other anuran species have been associated with pheromone production, suggesting that the inguinal glands described for O.centralis males may have a similar function.

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