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1.
SYNOPSIS. Fine structure of Pentatrichomonas hominis is described in the light of previous light microscopic findings. The relationships among kinetosomes #1-#4 and R are like those previously reported orhomonas gallinae, and the same is true of the rootlet filaments associated with the several kinetosomes. The kinetosome (I) of the independent flagellum is situated just behind the reflection of the sigmoid filaments of kinetosome #2 onto the pelta and parallels these filaments for a considerable distance. The peltaraxostylar junction consists of 3 layers: the capitulum of the axostyle (outer, the pelta (intermediate, and the sigmoid rootlets of kineto some #2 (inner). The pelta overlaps the axostylar capitulum to a variable extent. The parabasal body consists of elongate and flattened cisternae of smooth endoplasmic reticulum surrounded by numerous small vesicles. There are 2 typically cross-striated parabasal filaments, filament 2 probably contributing most, if not all, the material to the slender, periodic organelle that underlies the parabasal body and usually does not extend far beyond the posterior end of the nucleus. The periodic costa is paralleled by paracostal granules, but there are few, if any, paraxostylar granules. The ultrastructure of the costa appears to be a network of flattened hexagons, with a single fibril projecting thru each of the hexagonal areas. The major cross-striations are made up largely of densely-stained filaments which are occasionally cut in cross section. The undulating membrane consists of a cytoplasmic fold extending from the dorsal surface of the organism and of the attached part of the recurrent flagellum, which is closely applied to the fold. The segment of the membrane dorsal to the flagellum, presumably the “accessory filament,” contains the marginal lamella, a membrane folded upon itself and with periodicity virtually indistinguishable from that of the rootlet filament of kinetosome #1.  相似文献   

2.
SYNOPSIS. Tritrichomonas foetus shares many fine-structural features with the previously described genera of the subfamily Trichomonadinae. These include the arrangement and structure of the kinetosomes, of most rootlet filaments, including the sigmoid filaments of kinetosome #2, as well as those of the parabasal apparatus and of the pelta-axostyle complex. On the other hand, this species, and presumably all other Tritrichomonas augusta-type flagellates, differ from Trichomonadinae in certain important details. Among the features which T. foetus does not share with Trichomonadinae are the fine structure of the costa and of the undulating membrane, as well as several organelles not found in the latter subfamily. The costal base of Trichomonadinae is replaced in T. foetus and other Tritrichomonadinae by a comb-like structure, extending between the costa and the infrakinetosomal body. The suprakinetosomal body, connected to kinetosome #2 in the region of attachment of the sigmoid filaments, and the infrakinetosomal body, which appears to contribute to the proximal marginal lamella, are organelles evidently restricted to Tritrichomonadinae. The undulating membrane consists of 2 parts. The proximal part is a fold-like differentiation of the dorsal body surface, the dorsal part of which contains the proximal marginal lamella. The distal part of the undulating membrane, with no obvious physical connection to the fold, encloses the distal marginal lamella in its ventral, and the microtubules of the recurrent flagellum in its dorsal area. The organelle of T. foetus which by its size, certain structural characteristics, and relationship with the undulating membrane and some organelles, including the paracostal granules, is analogous to the costa of Trichomonadinae and of Trichomitopsis termopsidis (subfamily Tritrichomonadinae), conforms in the structure of its periodic cross-striations to that of the parabasal filaments of the latter organisms; its origin corresponds closely to that of parabasal filament 2 of Trichomonadinae.  相似文献   

3.
SYNOPSIS. Monocercomonas shares many fine-structural features with all other trichomonads. These include the basic arrangement of the kinetosomes as well as of the recurrent and 3 anterior flagella. The pelta-axostyle complex and the parabasal apparatus, i.e. the Golgi complex and the periodic filaments, also conform to the trichomonad pattern. Of interest with regard to the crucial evolutionary position of Monocercomonas, considered to represent the most primitive trichomonad type, is the fact that it has some structures in common with other Monocercomonadidae and Trichomonadinae and others in common with Devescovinidae and Tritrichomonadinae. Among the former organelles are the marginal lamella and the costal base, and among the latter, the comb-like organelle situated between the infrakinetosomal body and parabasal filament 2 as well as the infrakinetosomal body. No traces of either costa or undulating membrane have been noted, but a complex structure homologous to the marginal lamella of Hypotrichomonas and Trichomonadinae is found underlying the short anteriormost portion of the recurrent flagellum that is attached to the body surface. Observations of sections of selected division stages indicate the potential of parental kinetosomes #1 and #3 to become daughter kinetosome #2.  相似文献   

4.
SYNOPSIS. Tritrichomonas muris shares many fine-structural details with the previously described members of the family Trichomonadidae, and especially with the organisms belonging to the subfamily Tritrichomonadinae. Among the features which T. muris has in common with all Trichomonadidae and in all probability with other Trichomonadida are the arrangement and structure of: the kinetosomes; many rootlet filaments, including the sigmoid filaments of kinetosome #2; the parabasal apparatus; and the pelta-axostyle complex. The structures which T. muris-type flagellates share with other Tritrichomonadinae, and especially with Tritrichomonas augusta-type species (including T. foetus), but not with Trichomonadinae that have been studied to date, are: the Type A costa; a comb-like structure, which appears to have replaced the costal base of Trichomonadinae and of Hypotrichomonas; the suprakinetosomal body, rudimentary in T. muris; and the infrakinetosomal body. The undulating membrane, like that of T. augusta-type organisms, consists of a proximal and a distal part. The proximal part, which contains the proximal marginal lamella, is less developed in T. muris than in T. augusta-type flagellates, being represented by a relatively low ridge for the entire length of the organism. The distal part of the membrane in T. muris, on the other hand, is more highly developed; it is a heavy cord, with a distal marginal lamella which consists of a large triangular organelle having a highly ordered structure and 2 less well defined cords distal to this organelle. The tubules of the recurrent flagellum occupy the area distal to the cords. The sigmoid filaments of kinetosome #2, unlike those of other Trichomonadidae examined to date, extend posteriorly to the peltar-axostylar junction; they seem to terminate within the cytoplasm near, but not connected to the axostyle. In addition to the Type A costa, there is a small rootlet filament, which appears to be homologous to the rudimentary costa noted in Hypotrichomonas. Some of the paraxostylar and paracostal granules consist of an outer, relatively dense layer and an inner “core” of moderate density; between the 2 there is a lucent ring. The discussion deals in some detail with the possible nature of the paraxostylar and paracostal granules in trichomonads. The taxonomic status of Tritrichomonas cricetus (Wantland) [Tritrichomonas criceti (Wantland) emend. Levine] and Trichomonas criceti Ray & Sen Gupta is discussed in an appendix; it is concluded that both of these names are synonyms of T. muris (Grassi).  相似文献   

5.
The major components of the internal flagellar apparatus of Chilomonas paramecium Ehr. are two large microtubular roots and a striated root paralleled by three microtubules. The two microtubular roots overlap at the basal bodies. One microtubular root follows a curved path in the anterior of the cell, and the other extends straight to the posterior passing through a groove in the nucleus. The striated root extends laterally from the basal bodies. Except that it is smaller, the posteriorly directed root bears a strong resemblance to the axostyle of oxymonads. The overall arrangement and structure of the flagellar roots is similar to the pelta, axostyle and costa of trichomonads and the pelta and axostyle of oxymonads, groups of mitochondrion-less, largely parasitic or symbiotic protozoans. An affinity between cryptomonads and oxymonads or trichomonads would have many phylogenetic implications, some of which are discussed.  相似文献   

6.
SYNOPSIS. Culture forms and lumen-dwelling phases of the ameboflagellate Histomonas meleagridis, which are structurally indistinguishable from each other, have a single flagellum. Their well-developed pelta is connected to the anterior segment of the broad, spatulate axostylar capitulum, applied to the left-ventral surface of the nearly spheroid or somewhat ellipsoid or ovoid nucleus. The capitulum narrows into a very slender axostylar trunk that tapers to a fine point and does not project beyond the body surface. The parabasal apparatus consists of a V-shaped parabasal body and a large parabasal filament. A new flagellum appears early during division and soon approaches its full length. The 2 flagella persist thruout division and each becomes the locomotory organelle of a daughter histomonad. The arms of the parental parabasal body appear to separate, each going to 1 of the daughter mastigont systems; some parabasal material is lost early in division. The 2nd arm is regenerated in each daughter parabasal body. The large parabasal filament seems not to be retained in the parental mastigont system, and new filaments are seen at both poles before 2 daughter nuclei are formed. The old axostyle degenerates from the anterior toward the posterior end; at the same time lamellar primordia of the daughter pelta-axostyle complexes appear in the separating mastigont systems that are connected by an extranuclear spindle during the entire division process. The structure and taxonomic status of H. meleagridis are discussed in the light of this and previous studies.  相似文献   

7.
SYNOPSIS. The fine structure of Hypotrichomonas acosta resembles in many respects that of Trichomonadidae, and especially of members of the sub-family Trichomonadinae which have been examined to date by electron microscopy. In addition, the flagellate has certain ultrastructural differences from the latter organisms, some of which are of phylogenetic significance. Among these, the structure of the undulating membrane and the apparently occasional presence of a fine filament which may be considered as homologous to the costa of Trichomonadidae are the most important. The undulating membrane is represented by a rather low and otherwise poorly developed dorsal cytoplasmic fold with an ill-defined distal marginal lamella; the recurrent flagellum is applied near the dorsum of the fold. In a very few preparations a relatively short filament, of a diameter falling below the resolution limits of light microscope, is seen in a position which corresponds to that of the costa of Trichomonadidae. The identity of the filament as a probable rudimentary costa is supported also by the character of its periodicity. The rare appearance of the rudimentary costa among hundreds of sections may be explained either by its minute dimensions or by its absence from many hypotrichomonads. Other structures recorded for the first time in trichomonads are: the fine filamentous connections of the axostylar microtubules; the branching of parabasal filament 2; and the unusually organized, perhaps helical, polysomes, which are found in addition to the ribosomal complexes associated with the endoplasmic reticulum and commonly found in trichomonads. A detailed analysis of interconnections among various mastigont structures is presented and several kinds of cytoplasmic inclusions are described. H. acosta is of interest in the study of the nuclear envelope and presence of nuclear pores, which are numerous and conspicuous in this flagellate. The fine structure of the hypotrichomonad is discussed in relation to that of other trichomonads and in some instances to that of other protozoa.  相似文献   

8.
Coleman GS  Hall FJ 《Tissue & cell》1971,3(3):381-388
The structure of the organelles situated beneath the kinetosomes in the adoral zone of membranelles of the rumen ciliate Entodinium caudatum have been investigated in the electron microscope using the technique of negative staining. Each kinetosome was joined to a sub-kinetosomal plate and these plates were joined together in rows which in turn were more loosely linked to form a sheet. The structure or these plates is described and their relationship to similar structures in other protozoa is discussed. The nature of the argentophilic structures observed in the light microscope at the anterior end of Entodinium caudatum has also been investigated in the electron microscope.  相似文献   

9.
The fine structure of the axostyle in the protists Tritrichomonas foetus and Monocercomonas sp is described using transmission electron microscopy after quick-freezing techniques and immunocytochemistry. The axostyle microtubules presents a lateral projection formed by two protofilaments in addition to the 13 protofilaments normally found in microtubules. The axostyle is associated with other cell structures such as hydrogenosomes, endoplasmic reticulum, sigmoid filaments and glycogen particles. The microtubules of the pelta-axostylar system are connected to each other by bridges regularly spaced with an interval of 9 nm. Labeling of the axostyle was observed after cell incubation with monoclonal antibodies recognizing alpha-tubulin and acetylated-tubulin.  相似文献   

10.
The electron microscope was used to study the structure and three dimensional relationships of the components of the body cortex in thin sections of Paramecium multimicronucleatum. Micrographs of sections show that the cortex is covered externally by two closely apposed membranes (together ~250 A thick) constituting the pellicle. Beneath the pellicle the surface of the animal is molded into ridges that form a polygonal ridgework with depressed centers. It is these ridges that give the surface of the organism its characteristic configuration and correspond to the outer fibrillar system of the light microscope image. The outer ends of the trichocysts with their hood-shaped caps are located in the centers of the anterior and posterior ridges of each polygon. The cilia extend singly from the depressed centers of the surface polygons. Each cilium shows two axial filaments with 9 peripheral and parallel filaments embedded in a matrix and the whole surrouned by a thin ciliary membrane. The 9 peripheral filaments are double and these are evenly spaced in a circle around the central pair. The ciliary membrane is continuous with the outer member of the pellicular membrane, whereas the plasma membrane is continuous with the inner member of the pellicular membrane. At the level of the plasma membrane the proximal end of the cilium is continuous with its tube-shaped basal body or kinetosome. The peripheral filaments of the cilium, together with the material of cortical matrix which tends to condense around them, form the sheath of the basal body. The kinetodesma connecting the ciliary kinetosomes (inner fibrillar system of the light microscopist) is composed of a number of discrete fibrils which overlap in a shingle-like fashion. Each striated kinetosomal fibril originates from a ciliary kinetosome and runs parallel to other kinetosomal fibrils arising from posterior kinetosomes of a particular meridional array. Sections at the level of the ciliary kinetosomes reveal an additional fiber system, the infraciliary lattice system, which is separate and distinct from the kinetodesmal system. This system consists of a fibrous network of irregular polygons and runs roughly parallel to the surface of the animal. Mitochondria have a fine structure similar in general features to that described for a number of mammalian cell types, but different in certain details. The structures corresponding to cristae mitochondriales appear as finger-like projections or microvilli extending into the matrix of the organelle from the inner membrane of the paired mitochondrial membrane. The cortical cytoplasm contains also a particulate component and a system of vesicles respectively comparable to the nucleoprotein particles and to the endoplasmic reticulum described in various metazoan cell types. An accessory kinetosome has been observed in oblique sections of a number of non-dividing specimens slightly removed from the ciliary kinetosome and on the same meridional line as the cilia and trichocysts. Its position corresponds to the location of the kinetosome of the newly formed cilium in animals selected as being in the approaching fission stage of the life cycle.  相似文献   

11.
Stomatogenesis during metamorphosis of the marine loricate ciliate, Eufolliculina uhligi, was observed by transmission electron microscopy. Kinetosome proliferation in the stomatogenic territory leads to the formation of an anarchic field. This separates into the left adoral and the right paroral primordia. Both primordia consist of pairs of kinetosomes. One kinetosome of a pair is associated with one transverse and two postciliary microtubules; the other has one transverse microtubule. The postciliary microtubules of the adoral kinetosomes become divergent; those of the paroral kinetosomes become convergent. The adoral kinetosomes arrange in promembranelles. Then a third row of kinetosomes is produced anteriorly to each promembranelle. This third row is short at the peristome but longer in the buccal area. The paroral kinetosomes form a stichodyad. The buccal part of the paroral primordium is resorbed during formation of the buccal cavity. Stomatogenesis ends with the development of a functioning cytostome. During this process, the postciliary microtubules of the buccal adoral membranelles elongate and become associated with cytopharyngeal vesicles. Fusion of these vesicles with the cytostome has been observed some time after the completion of the oral structures.  相似文献   

12.
ABSTRACT. The cilia of Didinium nasutum are restricted to two girdles encircling the cell. Each row of cilia in both girdles is made up of two to three anterior pairs of kinetosomes followed by several single kinetosomes. Each single kinetosome has two sets of transverse microtubules, an overlapping postciliary microtubular ribbon, and a laterally directed kinetodesmal fiber. The pairs of kinetosomes are homologous to the oral dikinetids of other haptorians: the nonciliated kinetosome of the pair has a transverse microtubular ribbon that extends to line the membrane of the proboscis, a single short postciliary microtubule, and a nematodesma; the ciliated kinetosome has a ribbon of postciliary microtubules and two sets of transverse microtubules. The presence of these characters in Didinium invalidates Leipe & Hausmann's conclusion that the Didiniidae should be removed from the subclass that contains the other haptorians (Leipe, D. D. & Hausumann, K. 1989. Somatic infraciliature of the haptorid ciliate Homalozoon vermiculare (Kinetofragminophora, Gymnostomata) Ditransversalia n. subcl. and phylogenetic implications. J. Protozool. , 36 :280–289). In light of this, the justification for a subclass Ditransversalia is challenged and shown to be unnecessary.  相似文献   

13.
Transmission and scanning electron microscopy of specimens of Paramecium multimicronucleatum treated with the Rio-Hortega silver-impregnation method as modified by Fernández-Galiano demonstrate that considerable deposition of silver occurs around the kinetosomes, especially at the level of the basal plate and also at the proximal end of the kinetosome. In addition, silver is heavily deposited within the kinetodesmal fibers, in the fibrous matrix that surrounds the postciliary and transverse microtubules, in the connective structures observed between the two kinetosomes of a pair and between the kinetodesmal fiber and the anterior kinetosome, and in the trichocysts. Differences and similarities in sites of deposit when other methods of silver impregnation are employed are discussed and the particular value of the present technique in studies of ciliate systematics and phytogeny is stressed.  相似文献   

14.
I B Ra?kov 《Tsitologiia》1975,17(7):739-747
The ciliature of T. prenanti Dragesco 1960 (forma oligocineta Raikov et Kovaleva, 1968) consists of 14-18 ventral and lateral longitudinal kineties with paired kinetosomes, carrying either two cilia or one cilium per kinetosome pair (in the latter case, the nonciliated kinetosome is always the posterior one). The ectoplasmic fibrillar system belongs to the postciliary type. A pair of kinetosomes shares a common basal plate. The anterior kinetosome gives rise to a short ribbon of transverse microtubules, the posterior one, to a poorly developed kinetodesmal filament and to a strong ribbon of postciliary microtubules. The latter proceeds backwards along 8 to 12 kinetosome pairs, being incorporated into a laminated postciliodesma which accompanies each kinety on its right side. Rows of Golgi elements, sending secretory vesicles and channels towards the body surface, exist beneath the kinetosome bases. Each kinety is accompanied on its left by a microfibrillar myoneme, surrounded by perimyary vesicles and underlain by a row of mitochondria. The median part of the dorsal surface is nonciliated; the cytoplasm here is rich of membrane systems, contains peripheral, electron-dense, extrusible inclusions and sometimes also bacteria. The electron-dense inclusions develop in the endoplasm, in close contact with mitochondria. The endoplasm contains also large microfibrillar spheres of unknown nature.  相似文献   

15.
Tetramitus exhibits independent ameboid and flagellate stages of remarkable morphological dichotomy. Transformation of the ameba involves the formation of four kinetosomes and their flagella. The arrangement of these kinetosomes and associated whorls of microtubules extending under the pellicle establishes the asymmetric flagellate form. While no recognizable kinetosomal precursors have been seen in amebae, and there is no suggestion of self-replication in dividing flagellates, developmental stages of kinetosomes have been identified. These are occasionally seen in association with the nucleus or with dense bodies which lie either inside of or close to the proximal end of the prokinetosome. Outgrowth of flagella involves formation of an axoneme and a membrane. From the distal tip of the kinetosome microtubules grow into a short bud, which soon forms an expanded balloon containing a reticulum of finely beaded filaments. The free ends of the microtubules appear unraveled; they are seen first as single elements, then as doublets, and finally are arranged into a cylinder. Growth in length is accompanied by a reduction in the diameter of the balloon. The concept that the formation of the kinetic apparatus might involve a nuclear contribution, followed by a spontaneous assembly of microtubules, is suggested.  相似文献   

16.
SYNOPSIS. The fine structure of the cilium, kinetosome, kinetodesmal fiber, and basal microtubules has been described in Cyathodinium piriforme. The ciliary axoneme is encased in an electron-dense jacket termed the axonemal jacket. This jacket surrounds the axoneme and is found midway between the axoneme and the ciliary membrane when viewed in cross section. Before division or reorganization the cilia are withdrawn into the cell. Intact cilia surrounded by their jackets are found in the cytoplasm during the early phases of retraction. Degradation of the axonemal microtubules precedes the dissolution of the axonemal jacket. Profiles of the jackets are observed after the microtubules have been resorbed. The cilia appear to detach from the kinetosomes. Barren kinetosomes are seen below the cell surface frequently with kinetodesmal fibers still attached. Whether all or some of these barren kinetosomes contribute to the formation of the new ciliary anlage cannot be ascertained.  相似文献   

17.
SYNOPSIS. Monocercomonas molae from the hindgut of the sunfish Mola mola is described. The host was taken from southern California coastal waters in October, 1964. The body of the flagellate is 8.0 × 10.7 microns. A single basal granule complex gives rise to 4 flagella, one of which is recurrent. The axostyle is relatively stout, with argentophilic granules, and possesses a periaxostylar ring. The capitulum of the axostyle continues into the sickle-shaped pelta, and the parabasal body is rod-shaped or lobed and roughly triangular in cross-section.  相似文献   

18.
The fine structure of the dorsal bristle complex and pellicle of non-developing Euplotes eurystomus is described in detail by scanning and transmission electron microscopy. The bristle-pit unit is a highly differentiated complex of organelles. The bristle complex is composed of a pair of kinetosomes (basal bodies) joined by a connective. The anterior kinetosome bears the bristle cilium, which contains a polarized network of particles (“lasiosomes”). The posterior kinetosome bears a very short, knob-like “condylocilium,” and has an associated striated fiber. Accessory ribbons of microtubules are also associated with the kinetosome couplets. Parasomal sacs, a septum connecting the bristle cilium to the anterior wall of the pit, core granules of the kinetosomes, and large membranous ampules are described. The organization of the bristle complex bears many similarities to the somatic ciliature of other ciliates. The pellicle of Euplotes is composed of a continucus outer cell membrane subtended by membranous alveoli, which contain a “fibrous mat.” Two sheets of subpellicular microtubules (longitudinal and transverse) are located just beneath the alveoli. The “epiplasm” seen in some other ciliates is apparently absent in Euplotes. The texture of the cell surface is a pattern of folds or rugae composed of the outer cell membrane and the upper membrane of the alveolus. The pattern of rugae probably defines the “silverline-system” of light microscopy.  相似文献   

19.
Metopid armophoreans are ciliates commonly found in anaerobic environments worldwide; however, very little is known of their fine structure. In this study, the metopid Parametopidium circumlabens (Biggar and Wenrich 1932) Aescht, 1980, a common endocommensal of sea urchins, is investigated for the first time with emphasis on transmission electron microscopy, revealing several previously unknown elements of its morphology. Somatic dikinetids of P. circumlabens have a typical ribbon of transverse microtubules, an isolated microtubule near triplets 4 and 5 of the anterior kinetosome, plus two other microtubules between anterior and posterior kinetosomes, a short kinetodesmal striated fiber and long postciliary microtubules. In the dikinetids of the perizonal stripe, the kinetodesmal fiber is very pronounced, and there is a conspicuous microfibrillar network system associated with the kinetosomes. A new structure, shaped as a dense, roughly cylindrical mass surrounded by microtubules, is found associated with the posterior kinetosome of perizonal dikinetids. The paroral membrane is diplostichomonad and the adoral membranelles are of the “paramembranelle” type. Bayesian inference and maximum‐likelihood analysis of the 18S‐rDNA gene unambiguously placed P. circumlabens as sister group of the cluster formed by ((Atopospira galeata, Atopospira violacea) Metopus laminarius) + Clevelandellida, corroborating its classification within the Metopida.  相似文献   

20.
Trichomonas vaginalis is a flagellated parasitic protist of the human urogenital tract. The parasite has a poorly known cytoskeleton formed by an axostyle and a pelta, which are formed by stable structures such as microtubules, essential for the maintenance of cell shape and organization. FLUTAX-2 is an active fluorescent derivative of Taxol, binds to alphabeta-tubulin dimer polymerized. In this paper we present the analysis of microtubule distribution in living trophozoites of T. vaginalis using FLUTAX-2.  相似文献   

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