Wide Filaments Research Articles

Improved transient and steady‐state performance of series resonant ZCS high‐frequency inverter‐coupled voltage multiplier converter with dual mode PFM control scheme

AbstractA variety of switched‐mode high‐voltage DC power supplies using voltage‐fed‐type or current‐fed‐type high‐frequency transformer resonant inverters with MOS gate bipolar power transistors (IGBTs) have been recently developed for medical‐use X‐ray high power generators. In general, the high‐voltage high‐power X‐ray generator using voltage‐fed high‐frequency inverter with a high‐voltage transformer link has to meet some performances such as (i) short rising period in start transient of X‐ray tube voltage, (ii) no overshoot transient response in tube voltage, (iii) minimized voltage ripple in periodic steady‐state under extremely wide load variations and filament heater current fluctuation conditions of the X‐ray tube.This paper presents two lossless inductor snubber‐assisted series resonant zero current soft switching high‐frequency inverters using a diode‐capacitor ladder‐type voltage multiplier called Cockcroft‐Walton circuit, which is effectively implemented for a high DC voltage X‐ray power generator. This DC high‐voltage generator which incorporates a pulse frequency modulated series resonant inverter using IGBT power module packages is based on the operation principle of zero current soft switching commutation scheme under discontinuous resonant current and continuous resonant current transition modes. This series capacitor compensated for transformer resonant power converter with a high‐frequency transformer‐linked voltage boost multiplier can efficiently work a novel selectively changed dual mode PFM control scheme in order to improve the start transient and steady‐state response characteristics and can completely achieve stable zero current soft switching commutation tube filament current dependent on wide load parameter setting values with the aid of two lossless inductor snubbers. It is proved on the basis of simulation and experimental results in which a simple and low cost control implementation based on selectively changed dual‐mode PFM for high‐voltage X‐ray DC‐DC power converter with a voltage multiplier strategy has some specified voltage pattern tracking voltage response performances under rapid rising time and no overshoot in start transient tube voltage as well as the minimized steady‐state voltage ripple in tube voltage. © 2004 Wiley Periodicals, Inc. Electr Eng Jpn, 149(4): 60–72, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/eej.10345

Great promises yet to be fulfilled: Defining keratin intermediate filament function in vivo

Keratins are abundant proteins in epithelial cells, in which they occur as a cytoplasmic network of 10 - 12 nm wide intermediate filaments (IFs). They are encoded by a large family of conserved genes in mammals, with more than 50 individual members partitioned into two sequence types. A strict requirement for the heteropolymerization of type I and type II keratin proteins during filament formation underlies the pairwise transcriptional regulation of keratin genes. In addition, individual pairs are regulated in a tissue-type and differentiation-specific manner. Elucidating the rationale behind the diversity and differential distribution of keratin proteins offers the promise of novel insight into epithelial biology. At present, we know that keratin IFs act as resilient yet pliable scaffolds that endow epithelial cells with the ability to sustain mechanical and non-mechanical stresses. Accordingly, inherited mutations altering the coding sequence of keratins underlie several epithelial fragility disorders. In addition, keratin IFs influence the cellular response to pro-apoptotic signals in specific settings, and the routing of membrane proteins in polarized epithelia. Here we review studies focused on a subset of keratin genes, K6, K16 and K17, showing a complex regulation in vivo, including a widely known upregulation during wound repair and in diseased skin. Progress in defining the function of these and other keratins through gene manipulation in mice has been hampered by functional redundancy within the family. Still, detailed studies of the phenotype exhibited by K6 and K17 null mice yielded novel insight into the properties and function of keratin IFs in vivo.

Fossil actinomycete filaments and fungal hyphae in dicotyledonous wood from the Eocene London Clay, Isle-of-Sheppey, Kent, England

Two types of filamentous microfossil are preserved within vessel elements and rays of pyritized and partly carbonized twigs from the Lower Eocene London Clay. The first type, probably a Streptomyces-like actinomycete, is slender (<1 µm) with branches and some regular septation. Wider filaments (>2 µm) are fungal hyphae; no reproductive structures are preserved. These filamentous organisms probably started growing saprophytically after the death of the twigs; the fungi created lysis tracks on cell walls. Both are seen to pass through pyrite crystals that fill the lumina of some vessel elements, showing that they are not Recent contaminants.

Molecular architecture of intermediate filaments.

Together with microtubules and actin microfilaments, approximately 11 nm wide intermediate filaments (IFs) constitute the integrated, dynamic filament network present in the cytoplasm of metazoan cells. This network is critically involved in division, motility and other cellular processes. While the structures of microtubules and microfilaments are known in atomic detail, IF architecture is presently much less understood. The elementary 'building block' of IFs is a highly elongated, rod-like dimer based on an alpha-helical coiled-coil structure. Assembly of cytoplasmic IF proteins, such as vimentin, begins with a lateral association of dimers into tetramers and gradually into the so-called unit-length filaments (ULFs). Subsequently ULFs start to anneal longitudinally, ultimately yielding mature IFs after a compaction step. For nuclear lamins, however, assembly starts with a head-to-tail association of dimers. Recently, X-ray crystallographic data were obtained for several fragments of the vimentin dimer. Based on the dimer structure, molecular models of the tetramer and the entire filament are now a possibility.

Intermediate filaments: molecular structure, assembly mechanism, and integration into functionally distinct intracellular Scaffolds.

The superfamily of intermediate filament (IF) proteins contains at least 65 distinct proteins in man, which all assemble into approximately 10 nm wide filaments and are principal structural elements both in the nucleus and the cytoplasm with essential scaffolding functions in metazoan cells. At present, we have only circumstantial evidence of how the highly divergent primary sequences of IF proteins lead to the formation of seemingly similar polymers and how this correlates with their function in individual cells and tissues. Point mutations in IF proteins, particularly in lamins, have been demonstrated to lead to severe, inheritable multi-systemic diseases, thus underlining their importance at several functional levels. Recent structural work has now begun to shed some light onto the complex fine tuning of structure and function in these fibrous, coiled coil forming multidomain proteins and their contribution to cellular physiology and gene regulation.

Improved Transient and Steady-State Performances of Series Resonant ZCS High-Frequency Inverter-Coupled Voltage Multiplier Converter with Dual Mode PFM Control Scheme

The A variety of switched-mode high voltage DC power supplies using voltage-fed type or current-fed type high-frequency transformer resonant inverters using MOS gate bipolar power transistors; IGBTs have been recently developed so far for a medical-use X-ray high power generator. In general, the high voltage high power X-ray generator using voltage-fed high frequency inverter with a high voltage transformer link has to meet some performances such as (i) short rising period in start transient of X-ray tube voltage (ii) no overshoot transient response in tube voltage, (iii) minimized voltage ripple in periodic steady-state under extremely wide load variations and filament heater current fluctuation conditions of the X-ray tube. This paper presents two lossless inductor snubber-assisted series resonant zero current soft switching high-frequency inverter using a diode-capacitor ladder type voltage multiplier called Cockcroft-Walton circuit, which is effectively implemented for a high DC voltage X-ray power generator. This DC high voltage generator which incorporates pulse frequency modulated series resonant inverter using IGBT power module packages is based on the operation principle of zero current soft switching commutation scheme under discontinuous resonant current and continuous resonant current transition modes. This series capacitor compensated for transformer resonant power converter with a high frequency transformer linked voltage boost multiplier can efficiently work a novel selectively-changed dual mode PFM control scheme in order to improve the start transient and steady-state response characteristics and can completely achieve stable zero current soft switching commutation tube filament current dependent for wide load parameter setting values with the aid of two lossless inductor snubbers. It is proved on the basis of simulation and experimental results in which a simple and low cost control implementation based on selectively-changed dual-mode PFM for high-voltage X-ray DC-DC power converter with a voltage multiplier strategy has some specified voltage pattern tracking voltage response performances under rapid rising time and no overshoot in start transient tube voltage as well as the minimized steady-state voltage ripple in tube voltage.

Conspecificity of Elachista nigra and Elachista orbicularis (Elachistaceae, Phaeophyceae)

SUMMARY A taxonomic study of two brown algal species, Elachista nigra Takamatsu and Elachista orbicularis (Ohta) Skinner (Elachistaceae), was performed on the basis of morphological observations of field-collected and laboratory cultured specimens from Japan (including their type localities) and molecular phylogenetic analyses. The two species had been distinguished by developmental patterns of paraphysis- and plurizoidangium-bearing erect filaments, such filaments of E. nigra developing from wide erect filaments and those of E. orbicularis developing directly from basal prostrate filaments. However, many specimens investigated in the present study showed forms intermediate between these two patterns. Molecular phylogenetic analyses (including five additional elachistacean species) based on the internal transcribed spacer (ITS)2 region of the nuclear ribosomal RNA (nrRNA) gene showed a close relationship between all samples of E. nigra and E. orbicularis, and that the developmental patterns of paraphysis- and plurizoidangium-bearing erect filaments were homoplasious. On the basis of these morphological and molecular data, E. orbicularis was reduced to synonymy with E. nigra. The ITS2 sequences of E. nigra were significantly different between samples from the Sea of Japan and those from the Pacific Ocean with several insertion/deletion and substitution mutations.

The magnetic nature of wide EUV filament channels and their role in the mass loading of CMEs

Previous works have shown that dark and wide EUV lament channels observed at <912 A are due to absorption of EUV lines in cool plasma condensations that are not observed in H. We extend this interpretation and we address the issue of the possible injection of their mass into CMEs, through the magneto-hydrostatic modeling in 3D of one lament observed both in H and in EUV. The model parameters are xed so as to match the H observations only. Further comparison of the model with the EUV observations reveal the magnetic nature of the absorbing plasma condensations. They are formed in magnetic dips, as for the lament itself. Opacity ratios and the hydrostatic condition imply that the dips must be lled by cool material up to 1700 km, which increases the lament mass by 50% as compared to H estimations. Far from the lament, the absorbing condensations are located below 4 Mm in altitude above the photosphere, on the edge of weak photospheric parasitic polarities, within the lower parts of long eld lines overlaying the lament. By physical analogy with H lament feet, we redened these extended regions as EUV feet. The broadening of the EUV lament channel is dominated by EUV feet, while the larger lling of dips plays a non-negligible but minor role. Further implications from this work are discussed, on the visibility and the geometry of the condensations, on the existence of EUV lament channels in the absence of laments, on the loading of cool material into lament feet through bald patch reconnection and on the complex geometry of the upper prominence-corona transition region. The magnetic topology implies that during the lament eruption, the mass of its wide EUV feet will not contribute to the CME, whereas the extra mass provided by the large lling of dips in the lament flux tube will be loaded into the CME.

Evidence for a Heated Gas Bubble inside the "Cooling Flow" Region of MKW 3s

We report on the deep Chandra observation of the central r = 200 kpc region of the cluster of galaxies MKW 3s, which was previously identified as a moderate cooling flow cluster. The Chandra image reveals two striking features—a 100 kpc long and 21 kpc wide filament, extending from the center to the southwest, and a nearly circular, 50 kpc diameter depression 90 kpc south of the X-ray peak. The temperature map shows that the filamentary structure is colder while the surface brightness depression is hotter than the average cluster temperature at any radius. The hot and the cold regions indicate that both cooling and heating processes are taking place in the center of MKW 3s. We argue that the surface brightness depression is produced by a heated, low-density gas bubble along the line of sight. We suggest that the heated bubble is produced by short-lived nuclear outbursts from the central galaxy.

AA protein in experimental murine AA amyloid fibrils: A high resolution ultrastructural and immunohistochemical study comparing aldehyde-fixed and cryofixed tissues

In a previous study, the fibrils of experimental murine AA amyloid were found to be microfibril-like structures with the AA protein (in the form of 1 nm wide flexible filaments) on their exterior surface. in this study, we have re-examined the AA amyloid fibrils with advanced methods of cryofixation and freeze substitution which are known to retain ultrastructural detail as close as possible to the living state. The observations were compared to those obtained with conventional methods of aldehyde fixation. Cryofixation and freeze substitution confirmed the microfibril-like nature of the inner part of the AA amyloid fibril. The AA protein was present on the exterior surface in the form of 3 nm wide 'helical rods' formed by the tight coiling of the 1 nm wide AA protein flaments. The 'helical rods' were arranged parallel to the axis of the fibril and to one another with a uniform center-to-center distance of 5 nm. This arrangement was fully preserved in amyloidfibrils after cryofixation and freeze substitution, but was present in only some areas of formaldehyde fixed mouse spleen AA amyloid. This conformation and orientation of AA protein is likely to be that in its native state, given the ability of these advanced methods of biological preservation to retain structures close to that of the living state. This information should be of considerable value in comparing the structure of amyloid fibrils observed in situ with those isolated from tissue or generated in vitro.

Mesoscale physical and bio‐optical structure of the Antarctic Polar Front near 170°W during austral spring

As part of the U.S. Joint Global Ocean Flux Study Southern Ocean program, high‐resolution surveys of the Antarctic Polar Front near 170°W were conducted during October‐November 1997 with a towed undulating system equipped with conductivity‐temperature‐depth and bio‐optical sensors. Transects along 170°W and two successive mapping surveys revealed zonal bands with sharp meridional gradients in east‐west velocity. The Polar Front (PF) was characterized by a sea surface temperature drop from 1.6° to −1.6°C between 60.35° and 61.10°S, with eastward velocities of 0.4–0.5 m s−1 in the core of the PF jet. Deep mixed layers (&gt;200 m) were found within and north of the PF, but mixed layers shoaled to 100–125 m south of the PF to the edge of loose ice at 62.3°S. Highest mixed layer chlorophyll concentrations (0.35 mg m−3) in late October along 170°W were to the south of the PF and associated with cold, fresh water. A large meander of the PF was observed with an alongfront wavelength of 175 km, a cross‐front peak‐to‐peak amplitude of 100 km, and an eastward phase propagation of 0.05–0.08 m s−1, all of which are consistent with its formation via hydrodynamic instability of the PF jet. Highest‐phytoplankton biomass was located just poleward of the center of the PF jet. A high‐chlorophyll (up to 1.1 mg m−3) 50 by 50 km region was found downstream of the cyclonic bend associated with the meander. A survey 7.5 days later revealed growth of this high biomass region so that chlorophyll was in excess of 0.8 mg m−3 over an 80 km cross front by (at least) 80 km alongfront region. High biomass was observed to grow in place with respect to the meander rather than being displaced far downstream as would be expected from advection. This pattern is consistent with meander‐driven upwelling of nutrients and/or trace metals, which in turn stimulates phytoplankton growth. Detailed cross sections of the PF reveal narrow 10–20 km wide bands or filaments of phytoplankton biomass that have temperature/salinity properties distinct from surrounding water and are coherent for at least 120 km alongfront.

Time history of gain calculations in radiative-collisional model for X-ray lasers

We have performed the calculations of temporal characteristics of gain g(τ) on the 0-1 (4d-4p) transition and on the optically self-pumping 1-1 (4f-4d) transition of Ni-like krypton, g(τ) dependence on plasma electron density (n e ), temperature (T e ) and diameter (d) is outlined. The optimum plasma parameters: 5×10 17 50 eV. We found that time duration of laser action (τ las ) and g(τ) at maximum depend significantly on d. The effective laser in soft x-ray region is possible in a wide plasma filament with d>1 cm.

Lichenopyrenis galligena (Pleomassariaceae), a new genus of gall-forming lichenicolous fungi on Leptochidium

The new genus Lichenopyrenis is described for L. galligena, a cecidiogenous species parasitic on the lichen Leptochidium albociliatum. This genus is characterized by perithecioid ascomata with a cellular wall, formed by relatively large, somewhat compressed cells, fissitunicate, I- asci, wide hamathecium filaments, and 1-septate, pale orange brown ascospores with distoseptate thickenings which at maturity are seemingly bulging out of the exospore wall at the septum and apices. The conidia have a rhexolytic type of secession, and are attached to the conidiogenous cells by a separating cell. Lichenopyrenis is referred tentatively to the family Pleomassariaceae.

Ultrastructural verification of anchoring role of lamina fibroreticularis of dental basement membrane in odontogenesis.

In a previous study of the developing tooth a characteristic fibrillar layer associated with the basement membrane of the inner enamel epithelium was found to be a highly specialized lamina fibroreticularis of the basement membrane which is unusually rich in basotubules, 10 nm wide microfibril-like structures. In this study this layer was further examined in detail in the hope of ultrastructurally elucidating its role in odontogenesis. Tooth germs of the monkey (Macaca fuscata) were processed for thin section observations. Dental papilla cell processes were inserted into the lamina fibroreticularis and their surface was closely associated with numerous parallel basotubules. With high-resolution observations the space between the surface and nearest basotubules as well as the spaces between neighbouring basotubules were bridged by 1.5-3 nm wide filaments running perpendicular to the axis of basotubules. These results indicate that the processes of dental papilla cells are linked to groups of basotubules by means of 1.5-3 nm wide filaments. Immunoperoxidase staining showed the presence of fibronectin along basotubules as well as within the space between the process and basotubule. This result, together with the comparison of these filaments with microfibril-associated 1.2-3 nm wide fibronectin filaments and the reported abundance of fibronectin in the basement membrane area during odontogenesis, indicates that these 1.5-3 nm wide filaments are composed of fibronectin. After immunostaining for amyloid P component, done with the rat tissue because of the nature of an available antiserum, basotubules in the lamina fibroreticularis were positively stained, as has been shown in basotubules/microfibrils in other locations. Microfibrils function as anchoring rods by interlinking connective tissue components to one another and to the cells. Basotubules, thought to be basement membrane-incorporated microfibrils, in the lamina fibroreticularis in this study are also likely to function as an anchoring device to immobilize dental papilla cells along the basement membrane. Such an arrangement of mesenchymal cells is known to be crucial for the successful differentiation of odontoblasts in the developing tooth.

A high resolution ultrastructural comparison of isolated and in situ murine AA amyloid fibrils

There is an inconsistency between the ultrastructural organization of AA amyloid fibrils that have been isolated, which are composed of a slowly twisting set of two or more protofibrils, and those seen in situ, which are tubular entities with a tight helical substructure. in this study, the ultrastructure of fibrils isolated from experimental murine AA amyloid were observed at high resolution and compared with those seen in situ in the hope of clarifying the reason for this inconsistency. The fibrils in situ were composed of a microfibril-like 8-9 nm wide core covered by a layer of heparan sulfate proteoglycan (HSPG) to which 1 nm wide filaments, immunohistochemically identified as AA protein, were externally associated. Following isolation with the standard distilled water washing procedure, the HSPG layer and AA protein filaments detached from their core and dispersed into the water. The remaining denuded, variously loosened cores lost their typical appearance. in distilled water the detached 1 nm wide AA protein filaments became quite conspicuous and coiled themselves into 3 nm wide tight helices which in turn assembled into the characteristic slowly twisting sets of two parallel protofibrils similar to that previously reported as “isolated amyloid fibrils”. The results emphasize that great caution must be taken in extrapolating amyloid fibril structure from isolated preparations to in situ tissue conditions.

Ultrastructural organization of hemodialysis-associated β2-microglobulin amyloid fibrils

Fibrils of hemodialysis-associated beta 2-microglobulin amyloid were examined by high resolution electron microscopy and immunohistochemical labeling. The amyloid containing tissues obtained through autopsy were prepared for thin section observations. In contrast to other forms of amyloid, the most conspicuous feature of these fibrils were their curved conformations. The fibril core showed ultrastructural and immunohistochemical features in common with the core of connective tissue microfibrils and of previously observed fibrils of experimental murine AA amyloidosis and familial amyloid polyneuropathy (FAP). The core was wrapped in a layer of 3 nm wide ribbon-like "double tracked" structures identified as chondroitin sulfate proteoglycan (CSPG) with immunogold labeling as well as from the results of previous in vitro experiments. Finally, the outer surface of the fibril was associated with a loose assembly of 1 nm wide filaments immunohistochemically identified as beta 2-microglobulin. This is similar to the manner in which AA protein and transthyretin filaments are associated with their respective fibrils. The results of this study provide an additional example for the concept that amyloid fibrils in general are microfibril-like structures externally associated with amyloid protein filaments. An unusual feature of the fibrils of hemodialysis-associated amyloid, however, is the presence of a peripheral layer composed of CSPG rather than of heparan sulfate proteoglycan (HSPG) as in the case of the other two amyloids above. These chondroitin sulfate chains in the outer CSPG layer may be less effective in providing rigidity to the fibril core, thus allowing for the curved conformations of beta 2-microglobulin amyloid fibrils.

Threshold Detection and Semmes-Weinstein Monofilaments

Semmes-Weinstein monofilaments provide a repeatable instrument stimulus with a small standard deviation in contrast to other handheld test instruments, making them an optimum choice for objective sensory testing in a variety of clinics. Normal sensory detection thresholds for the entire body, and the stimulus force for each filament, were determined by Weinstein. He found a nylon filament of 0.005 in wide and 38 mm long (mean force, 68 mg) to be a good predictor of "normal" light touch-deep pressure threshold for the hands and most of the body. However, manufacturers of the nylon used in making the filaments allow an 8-10% tolerance in diameter. This small change in diameter can result in small variations in mean force among filaments of a given size. It has not been previously determined what effect this small variance in force has on the accuracy of the 2.83 (marking number) 0.005-in wide filament most often used for normal threshold detection. This study compared the 2.83 filaments available at the Gillis W. Long Hansen's Disease Center, which have a mean force of 62 mg, with those from North Coast Medical, Inc., which have a mean force of 95 mg. The filaments were used by 6 examiners in a standard testing protocol for the hands, arms, faces, legs, and feet of 130 subjects. Heavier and lighter filaments of measured force were also included. Results showed a high correlation in responses for two values for the 2.83 filaments in the range specified. On detailed analysis between kits there were some differences for site and age. The 2.83 filament was a good predictor of normal in both kits for the hand, the arm, and the leg, as was expected. It was suprathreshold for the face, making use of a lighter filament possible for facial testing, and subthreshold for the plantar surface of the foot, which required a slightly heavier filament (3.61 marking number, mean force, 279 mg) for normal threshold detection as measured in this study.

Characterization of the fibrillar layer at the epithelial-mesenchymal junction in tooth germs

A characteristic layer containing numerous fibrils is associated with the basement membrane of the inner enamel epithelium during the early stages of odontogenesis. However, its nature is not well understood. In this study, the layer was examined with high-resolution electron microscopy and immuno-histochemical staining. Tooth germs of monkeys (Macaca fuscata) were studied and each fibril in the layer was found to be a tubular structure, 8-9 nm in width, resembling a "basotubule", the tubular structure previously observed in various basement membranes. The space between the fibrils was filled with a network formed by irregular anastomosing strands with an average thickness of 4 nm; these strands resembled the "cords" forming the network in the lamina densa of basement membranes. After immunoperoxidase staining, fine threads immunoreactive for laminin staining were seen winding along the strands of the network, and 1.5-nm wide filaments, immunoreactive for type IV collagen, took the form of a network arrangement. The 5-nm-wide ribbon-like structures associated with the strands were identified as heparan sulfate proteoglycan by immunostaining. These results are similar to those obtained for the cord network of the lamina densa. The "fibrillar layer" therefore represents a highly specialized lamina fibroreticularis of the basement membrane of the inner enamel epithelium, and rich in basotubules.

Chasing Coiled Coils: Intermediate Filaments in Plants

AbstractThe cytoskeleton's structurally most resilient components, the intermediate filaments (IFs), have attracted the interest of cell biologists for more than two decades. IFs form extensive networks in many animal cells, and are thought to provide considerable tensile strength to the cells and tissues. In fact, the term “cytoskeleton” has originally been coined for the insoluble fibrous remains of detergent extracted animal cells. Nevertheless, cells can survive quite well without an IF network, and even without the subunit proteins that build the 10 nm wide polymeric filaments. Hence, the vital function of these cytoskeletal components is still hotly debated. Against this background, it may be premature to start suggesting functions for IFs in plants. Yet this is exactly what quite a number of researchers have begun to do. Because much recent evidence supports the idea of a plant IF cytoskeleton, it seems timely to examine this evidence and discuss its impact on our current understanding of IF function.

The structural organization of the pathogenic protozoan Tritrichomonas foetus as seen in replicas of quick frozen, freeze-fractured and deep etched cells

The quick-freezing and freeze-etching technique was used to analyse the cytoskeleton of Tritrichomonas foetus, a pathogenic protozoan of the urogenital tract of cattle. The cytoplasm presented a network of filamentous structures interacting with each other, with the surface of the hydrogenosomes and the nuclear membrane. Two nm wide filamentous structures were found in the luminal space of the Golgi complex, connecting the two faces of each cisterna. The microtubules of the pelta-axostyle system were connected by bridges 30-40 nm long and 10 nm wide, regularly spaced with an interval of 25 nm. The costa is a structure formed by a complex array of filaments and globous structures. It seems to be connected to the recurrent flagellum through a complex network formed by 15 and 10 nm wide filaments which emerge from the peripheral region of the costa and penetrate into the surface projections of the protozoan body to which the recurrent flagellum is attached. Other filaments were seen connecting the surface of these projections with the surface of the flagellum.