Ultrastructure of the Protonephridia of Syndisyrinx-Punicea (Hickman, 1956) (Rhabdocoela, Umagillidae) and Pterastericola-Pellucida Jondelius, 1989 (Rhabdocoela, Pterastericolidae)

1992 ◽  
Vol 40 (4) ◽  
pp. 385 ◽  
Author(s):  
K Rohde ◽  
NA Watson ◽  
U Jondelius
Keyword(s):  
Cell Membrane ◽  
Septate Junction ◽  
Variable Size ◽  
Single Row ◽  
Similar Morphology ◽  
Longitudinal Ribs ◽  
Surface Cell

Many flame bulbs of Syndisyrinx punicea (Rhabdocoela: Umagillidae) are formed by one perikaryon containing many mitochondria and a reticulum of membranes mainly in its periphery. Large liquid-filled lacunae were seen in the perikaryon and adjacent to it. Flame bulbs are without junctions, without external and internal leptotriches; the weir consists of some indistinct longitudinal ribs of variable size arranged in a single row, and bundles of microtubules extend along the flame bulb. Cilia are tightly packed, with microtubules oriented identically. Many flame bulbs open into one capillary with a long convoluted, partly septate junction extending to the surface cell membrane, with many microtubules running parallel with the capillary, and lateral flames. In Pterastericola pellucida (Rhabdocoela: Pterastericolidae), flame bulbs and capillaries have a similar structure, but the reticulum is more extensive, and the ribs of the weir are more distinct. The structure of the flame bulbs supports the view (based on similar morphology and hosts) that the Umagillidae and the Pterastericolidae are closely related to each other, and are typical 'turbellarian' Rhabdocoela. Many flame bulbs connected to a single perikaryon, flame bulbs with a single row of longitudinal ribs and bundles of microtubules but lacking internal leptotriches and a septate junction are synapomorphic for the Rhabdocoela (excluding the Neodermata).

Novel Protonephridial Filtration Apparatus in Cylindrostoma fingalianum, Allostoma sp. and Pseudostomum quadrioculatum (Platyhelminthes: Prolecithophora)

1997 ◽  
Vol 45 (6) ◽  
pp. 621 ◽  
Author(s):  
Nikki A. Watson ◽  
Klaus Rohde
Keyword(s):  
Septate Junction ◽  
Terminal Cell ◽  
Cylinder Wall ◽  
Simple Type ◽  
Cell Column ◽  
Longitudinal Ribs ◽  
The Family ◽  
Filtration Apparatus ◽  
Phylogenetic Resolution

The diverse types of protonephridial filtration apparatus in the Platyhelminthes provide valuable characters for phylogenetic resolution, yet only one species from the order Prolecithophora has previously been studied. We examined three further species, two belonging to the family Cylindrostomidae and one from the Pseudostomidae, and found a novel arrangement consisting of scattered, short filtration slits in the cytoplasmic cylinder of the terminal cell surrounding the flame of cilia. In these species there are no regular, longitudinal ‘ribs’, such as are found in many other platyhelminth taxa, nor bundles of supporting microtubules in the cylinder wall, and cilia arise at various levels throughout the long terminal cell column rather than in a group at the base of the flame, as is found in most other taxa. The perikaryon lies adjacent to the flame, the wall surrounding the lumen is strengthened by long, cross-striated ciliary rootlets, and the terminal cell is joined to the proximal canal by a septate junction. This simple type of filtration structure bears some resemblance to that found in Tricladida, but is distinctly different from that described in another prolecithophoran, Archimonotresis limophila (Protomonotresidae). This suggests that there may be a fundamental division within the Prolecithophora with regard to protonephridial filtration structures.

Ultrastructure of the Epidermis and Protonephridium of an Undescribed Species of Luridae (Platyhelminthes, Rhabdocoela)

1993 ◽  
Vol 41 (4) ◽  
pp. 415 ◽  
Author(s):  
K Rohde ◽  
NA Watson ◽  
A Faubel
Keyword(s):  
Extracellular Matrix ◽  
Single Cell ◽  
Basal Lamina ◽  
Dense Material ◽  
Undescribed Species ◽  
Single Row ◽  
Longitudinal Ribs ◽  
Capillary Walls

The epidermis of an undescribed species of Luridae possesses many large cavities filled with a medium-dense material, intraepidermal nuclei, glandular ducts, cilia with vertical and horizontal rootlets, surface microvilli, and a thick basal lamina. Cilia have narrow tips, the peripheral axonemal doublets lose one of the microtubules and, finally, whole doublets are lost near the tip. Flame bulbs have a single row of longitudinal ribs containing microtubules and connected by a 'membrane' apparently of extracellular matrix; cilia of flame bulbs possess cross-striated rootlets, and capillary walls are smooth. The nucleus of the protonephridium was observed near the tip of the flame bulb, along the capillary. It is not clear whether one perikaryon forms more than one flame bulb. The structure of the epidermal ciliary rootlets, the presence of intraepidermal nuclei, and flame bulbs composed of a single row of longitudinal ribs containing microtubules formed by a single cell are typical rhabdocoel characteristics.

Poster Sessions CP06: Cell Surface, Cell Membrane

2008 ◽  
Vol 81 ◽  
pp. 95-95
Author(s):  
D. K. H. Chou ◽  
M. Schachner ◽  
F. B. Jungalwala
Keyword(s):  
Cell Membrane ◽  
Cell Surface ◽  
Surface Cell ◽  
Poster Sessions

Electrophysiology of mammalian gland cells

1976 ◽  
Vol 56 (3) ◽  
pp. 535-577 ◽  
Author(s):  
O. H. Petersen
Keyword(s):  
Membrane Potential ◽  
Cell Membrane ◽  
Concentration Gradient ◽  
Gland Cell ◽  
Membrane Resistance ◽  
Transport Processes ◽  
Receptor Interaction ◽  
Cellular Transport ◽  
Gland Cells ◽  
Surface Cell

The resting cell membrane potential varies from -40 to -70 mV according to type of gland cell and species. The RP depends mainly on the large transmembrane concentration gradient for K maintained by a pump mechanism extruding Na and accumulating K. Since the Na permeability (PNa) is much smaller than PK, the Na concentration gradient is less important. In addition to the dominant electrodiffusional control of RP the Na pump itself contributes since the active transport of Na (out) exceeds that of the active K uptake. Gland cells are generally electrically coupled--i.e., the junctional membrane resistance is much lower than the surface membrane resistance. The coupling may be widespread (e.g., liver) or confined to one acinus (e.g., salivary gland and pancreas). The specific surface cell membrane resistance may be about 2000 omega cm2. A number of neurotransmitters and hormones control cellular transport processes by their action on surface cell membrane receptors. Agonist-receptor interaction causes prominent changes in membrane potential and resistance, in many cases of a complex nature. Most gland cell membranes so far investigated in detail appear to be electrically inexcitable; i.e., stimulation does not cause the appearance of action potentials (e.g., salivary glands, exocrine pancreas, and liver) but prominent exceptions to this are the endocrine pancreas (beta-cells) and the adrenal cortex. The main importance of agonist-induced membrane permeability changes is to alter the intracellular ion activities. An increase in [Na+] seems to be important whenever stimulation results in fluid transport and an increase in [Ca2+] triggers exocytosis.

scholarly journals THE ULTRASTRUCTURE OF THE PELLICLE COMPLEX OF EUGLENA GRACILIS

1965 ◽  
Vol 24 (2) ◽  
pp. 253-257 ◽  
Author(s):  
Joachim R. Sommer
Keyword(s):  
Cell Membrane ◽  
Euglena Gracilis ◽  
Unit Membrane ◽  
Single Row ◽  
Entire Cell

The pellicle complex of E. gracilis is composed of the cell membrane, the ridge and groove with the notch, four fibrils, and the subpellicular ER. The cell membrane is of unit membrane configuration and covers the outside of the cell, the cytostome, the gullet, and the reservoir. The notch of the pellicle complex has always a close topographic relationship to two particular fibrils, as well as the subpellicular ER. The gullet is that region between the reservoir and the cytostome which, in addition to longitudinal fibrils, is surrounded by a single row of circular fibrils. The circumference of the cytostome has twenty large pellicular ridges alternating with small pellicular ridges. Alternating tall and small pellicular ridges cover the entire cell during division.

scholarly journals Frustulia tunariensis sp. nov. (Bacillariophyceae) from the Andes of Bolivia, South America

Diversity ◽  
2020 ◽  
Vol 12 (9) ◽  
pp. 362
Author(s):  
Eduardo A. Morales
Keyword(s):  
Literature Review ◽  
South America ◽  
High Altitude ◽  
New Taxon ◽  
Single Row ◽  
Longitudinal Ribs ◽  
The Andes ◽  
Geographic Coverage ◽  
Bolivian Altiplano

Frustulia tunariensis sp. nov. is originated from a high-altitude peatland in the Tunari Cordillera, a branch of the Andean range in Bolivia. The new taxon is distinguished by the thick longitudinal ribs, the globose polar nodule with faint helictoglossa that does not produce an apical extension, and by the high areola and stria density, not found in any of the morphologically closely related taxa. Features of the folded valvocopula, such as the presence of a siliceous membrane as pars interior, and poroids present in the tube-like portion opening as slits to the valve interior and as a single row of poroids to the exterior, are also unique characters in the new taxon. Based on a literature review, a comparison of the newly proposed species with morphologically similar taxa was made. Also, published information shows the potential of girdle bands to distinguish groups of species and species themselves within Frustulia. Likewise, remarks on the ecological and distribution aspects of Frustulia in the Bolivian Altiplano are included, focusing on taxonomic quality, geographic coverage and sampling, and potential to represent the genus in the high Bolivian Andean plateau.

scholarly journals THE CELL JUNCTION IN A LAMELLIBRANCH GILL CILIATED EPITHELIUM

1970 ◽  
Vol 47 (2) ◽  
pp. 468-487 ◽  
Author(s):  
P. Satir ◽  
N. B. Gilula
Keyword(s):  
Cell Membrane ◽  
Smooth Endoplasmic Reticulum ◽  
Freshwater Mussel ◽  
Septate Junction ◽  
Cell Junction ◽  
Junctional Complex ◽  
Regional Differentiation ◽  
Ion Permeability ◽  
Membrane Surfaces ◽  
Entire Cell

The junctional complex in the gill epithelium of the freshwater mussel (Elliptio complanatus) consists of an intermediary junction followed by a 2–3 µ long septate junction. Homologous and heterologous cell pairs are connected by this junction. After fixation with 1% OsO4 containing 1% potassium pyroantimonate, electron microscopy of the gill reveals deposits of electron-opaque precipitate, specifically and consistently localized along cellular membranes. In both junctional and nonjunctional membrane regions, the precipitate usefully outlines the convolutions without obliterating the 150 A intercellular space, which suggests the rarity or absence of either vertebrate-type gap or tight junctions along the entire cell border. The precipitate appears on the cytoplasmic side of the limiting unit membranes of frontal (F), laterofrontal (LF), intermediate (I), lateral (L), and postlateral (PL) cells. The membrane surfaces of certain vesicles of the smooth endoplasmic reticulum, of multivesicular bodies, and of mitochondrial cristae contain precipitate, as does the nucleolus. In other portions of the cell, precipitate is largely absent. The amount of over-all deposition is variable and depends on the treatment of the tissue prior to fixation. Deposition is usually enhanced by pretreatment with 40 mM NaCl as opposed to 40 mM KCl, which suggests that the precipitate is in part sodium pyroantimonate. Treatment with 0.2 mM ouabain does not enhance deposition. Regional differentiation of cell membranes with respect to their ability to precipitate pyroantimonate is found in at least three instances: (a) between the ciliary membranes and other portions of the cell membrane: the precipitate terminates abruptly at the ciliary base, (b) between the LF and I cell borders: the precipitate is asymmetric, favoring the LF side of the junction, and (c) between the septate junctional membrane and adjacent membrane: the precipitate occurs periodically throughout the septate junction region with the periodicity corresponding to the spacing of the septa. This suggests that different regions of the cell membrane may have differing ion permeability properties and, in particular, that the septa may be the regions of high ion permeability in the septate junction.

Sarcolemmal permeability changes during early myocardial anoxia

1978 ◽  
Vol 36 (2) ◽  
pp. 642-643
Author(s):  
M. Ashraf ◽  
L. Landa ◽  
L. Nimmo ◽  
C. M. Bloor
Keyword(s):  
Cell Membrane ◽  
Membrane Permeability ◽  
Coronary Artery Occlusion ◽  
Artery Occlusion ◽  
Cell Membrane Permeability ◽  
Enzyme Release ◽  
Sprague Dawley ◽  
Sprague Dawley Rats ◽  
Sarcolemmal Permeability ◽  
Membrane Changes

Following coronary artery occlusion, the myocardial cells lose intracellular enzymes that appear in the serum 3 hrs later. By this time the cells in the ischemic zone have already undergone irreversible changes, and the cell membrane permeability is variably altered in the ischemic cells. At certain stages or intervals the cell membrane changes, allowing release of cytoplasmic enzymes. To correlate the changes in cell membrane permeability with the enzyme release, we used colloidal lanthanum (La+++) as a histological permeability marker in the isolated perfused hearts. The hearts removed from sprague-Dawley rats were perfused with standard Krebs-Henseleit medium gassed with 95% O2 + 5% CO2. The hypoxic medium contained mannitol instead of dextrose and was bubbled with 95% N2 + 5% CO2. The final osmolarity of the medium was 295 M osmol, pH 7. 4.

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