Structure of taste buds in foliate papillae of the rhesus monkey, Macaca mulatta

Taste buds in foliate papillae of the rhesus monkey were examined by electron microscopy. Three distinct cell types were identified. Type I cells were narrow elongated cells containing an oval nucleus, bundles of intermediate filaments, several Golgi bodies, and characteristic apical membrane-bounded dense granules. These cells exhibited morphological variations: some had a moderately dense cytoplasm, perinuclear free ribosomes, and flattened sacs of rough endoplasmic reticulum; others had a more lucent cytoplasm, dilated irregular rough endoplasmic reticulum, lysosome-like dense bodies, and lipid droplets. Type II cells typically contained a spherical, pale nucleus, a prominent nucleolus, supranuclear and infranuclear Golgi bodies, mitochondria with tubular cristae, and one or two centrioles. This cell type, too, showed some variation in the relative amounts of ribosomes and smooth endoplasmic reticulum, which varied inversely with each other. Type III cells were characterized by a clear apical cytoplasm essentially devoid of ribosomes and containing microtubules. In a few type III cells, the peri- and infranuclear regions contained many ribosomes and some rough endoplasmic reticulum. In most Type III cells, there were large numbers of dense and clear vesicles in the peri- and infranuclear regions; some of the vesicles were grouped in synapse-like arrangements with adjacent nerves. The morphological variations exhibited by all three cell types could be accounted for by age differences in each of the cells. This would be consistent with the notion that cell renewal occurs in each of the three cell populations.     

Cryptobia udonellae sp. n. (Kinetoplastidea: Cryptobiida) - parasites of the excretory system of Udonella murmanica (Udonellida)

A new cryptobiid flagellates, Cryptobia udonellae sp. n., is described from the excretory channels of Udonella murmanica. The body of flagellates is spindle-shaped. The flagellar pocket is subapical. Two flagella emerge from the pocket. One flagellum turns anterior and is forward-directed; the other flagellum is directed posterior and close to the ventral cell surface. The ventral groove is well developed. The cytostome opens just anterior to the flagellar pocket. The cytostome leads to the short cytopharynx. In the excretory channel of worms the flagellates C. udonellae sp. n. are attached to microvilli of epithelium or lay free in the lumen. Both flagellates have been studied with TEM. The unusual parasite system which involves organisms of four different phylums of animals has been described for the first time.     

The Fine Structure of the Colonial Colorless Flagellates Rhipidodendron splendidum Stein and Spongomonas uvella Stein with Special Reference to the Flagellar Apparatus

SYNOPSIS. The cell structure of the colorless colonial flagellates Rhipidodendron splendidum Stein and Spongomonas uvella Stein has been examined by electron microscopy to assertain their phylogenetic affinities. The cylindrical cells of R. splendidum have 2 smooth flagella of equal length, an asymmetrical flagellar pocket supported by microtubules, and a curved pit between the latter and an anterior prolongation of the cell. The matrix of the branched tubes comprising the fanshaped colony is composed largely of dense spherules which are produced in special cytoplasmic vesicles some of which contain symbiotic bacteria. The anterior nucleus has a flattened sac pressed closely against its posterior end. The sac has a long tail extending deep into the cytoplasm, a single bounding membrane and homogeneous contents. Several types of vesicle are described but food vacuoles and contractile vacuoles could not be positively identified. A kinetoplast mitochondrion is not present. The various cross-banded, microtubular and amorphous components of the complex and highly asymmetrical flagellar root system are described in detail and a 3-dimensional reconstruction is provided.
The ovoid cells of S. uvella are basically similar to those of R. splendidum ; though a nuclear sac is missing, there are some detailed differences in the structure of the flagellar root system, and bacteria are never present in the vesicles producing the matrix granules. Notwithstanding much similarity, Rhipidodendron is not combined with Spongomonas because of the basic difference in colony structure.
The possible relationships of R. splendidum and S. uvella with other groups are examined and it is concluded that they cannot be considered as colorless chrysomonads as previously thought or considered to be related to any of the other orders comprising the class Phytomastigophorea. They do not, however, appear to be related to any of the orders at present comprising the Zoomastigophorea.     

The fine structure of blood cells in the ascidian Perophora viridis

The fine structure of each of the blood cell types of Perophora viridis has been characterized and strong evidence for localization of vanadium in two of these types is given. There are eight cell types; phagocytes which may contain completely engulfed cells, lymphocytes with a prominant nucleolus and scanty cytoplasm packed with clustered ribosomes, and six other cell types each with distinctive granules. Morula cells contain a central nucleus and cytoplasm filled by wedged bodies, about five of which are seen in section. These bodies contain regularly spaced electron dense foci. Green cells have the same organization but contain bodies which are electron dense throughout. Granular amoebocytes contain many smaller lightly staining oval bodies and much glycogen. Another cell type (probably orange cells of light microscopy) contains numerous granular rounded bodies. Compartment cells have vacuoles containing electron dense particles and signet ring cells have usually one large vacuole which is electron dense lined and may contain electron dense particles. Developmental stages of these cell types show involvement of endoplasmic reticulum and Golgi bodies in granule formation. After glutaraldehyde fixation alone the only extremely electron dense components are particles in the compartment cells and signet ring cells implicating these as sites of vanadium localization, although not excluding other cell types.     

Ultrastructure of the flagellate Cruzella marina (Kinetoplastidea)

The ultrastructure of a marine, free-living heterotrophic kinetoplastid Cruzella marina was investigated with special attention being paid to the mitochondrion and flagellar organization. The flagellates have a polykinetoplastidal mitochondrion. Two flagella emerge from the pocket; one of these turns anteriorly being forward-directed, while the other is posteriorly directed to be adjacent to the ventral cell surface. The transition zone of both the flagella includes central filaments. The cytostome opens on the tip of the rostrum. The cytostome leads to the channel of cytopharynx, which penetrates the rostrum and proceeds into the flagellate body cytoplasm. The comparison of the relevant morphological and molecular data suggest that C. marina may arise early in the Kinetoplastidea lineage, before divergence of the majority taxa of the kinetoplastid flagellates.     

Cytologic characteristics and origin of naked nuclei in breast aspirate smears

To elucidate the origin of "naked nuclei" in breast aspiration smears, 17 cases of fibroadenoma were studied by light and electron microscopy. The ATPase reaction was also studied at both levels. The aspirates contained two types of naked nuclei: denuded degenerated nuclei and oval to spindle-shaped nuclei with very scanty cytoplasm. The cytoplasm of the latter was rich in free ribosomes and rough-surfaced endoplasmic reticulum but was devoid of cytoplasmic filaments and dense bodies. These cells were negative for ATPase activity. Stromal cells, not myoepithelial cells, characteristically demonstrated such cellular features in the aspirates and tissue sections studied. We conclude that most naked nuclei are derived from stromal cells.     

Fine structure of nerve cells in a planarian

The fine structure of the nerve cell types in the white planarian Procotyla fluviatilis were described. Ganglion cells comprise the major portion of the brain. These cells are irregular in shape with several cytoplasmic processes and contain ribosomes, a sparse endoplasmic reticulum, microtubules, lysosomes, and a Golgi apparatus with numerous small vesicles. Granule-containing cells are situated in the peripheral regions of the brain and along the nerve cords. These cells contain ribosomes, rough-surfaced endoplasmic reticulum and a Golgi apparatus with associated dense granules. The granules occupy most of the cytoplasm and are ～ 750A in diameter with moderately dense contents, ～ 750A with opaque contents, and ～ 1000A with contents of medium density. These granules are similar to those in the nervous systems of higher animals that contain epinephrine, norepinephrine, and neurosecretory substance, respectively. Each cell contains predominantly one type of granule although there is some intermixing of granules and intermediate types between the three most abundant granules. Small clear vesicles, resembling cholinergic synaptic vesicles, and all types of dense granules occur in the neuropil and within nerve endings.     

Characterization of polymer release from the flagellar pocket of Leishmania mexicana promastigotes

Trypanosomatids contain a unique compartment, the flagellar pocket, formed by an invagination of the plasma membrane at the base of the flagellum, which is considered to be the sole cellular site for endocytosis and exocytosis of macromolecules. The culture supernatant of Leishmania mexicana promastigotes, the insect stage of this protozoan parasite, contains two types of polymers: a filamentous acid phosphatase (sAP) composed of a 100-kD phosphoglycoprotein with non- covalently associated proteo high molecular weight phosphoglycan (proteo-HMWPG) and fibrous material termed network consisting of complex phosphoglycans. Secretion of both polymers is investigated using mAbs and a combination of light and electron microscopic techniques. Long filaments of sAP are detectable in the lumen of the flagellar pocket. Both sAP filaments and network material emerge from the ostium of the flagellar pocket. While sAP filaments detach from the cells, the fibrous network frequently remains associated with the anterior end of the parasites and can be found in the center of cell aggregates. The related species L. major forms similar networks. Since polymeric structures cannot be detected in intracellular compartments, it is proposed that monomeric or, possibly, oligomeric subunits synthesized in the cells are secreted into the flagellar pocket. Polymer formation from subunits is suggested to occur in the lumen of the pocket before release into the culture medium or, naturally, into the gut of infected sandflies.     

Unique localization of protein gene product 9.5 in type B synoviocytes in the joints of the horse.

Fibroblast-like (Type B) synoviocytes are cells in the synovial membrane that are responsible for production of both synovial fluid and the extracellular matrix in the synovial intima. Immunostaining of the horse synovial membrane for protein gene product (PGP) 9.5, which is a neuron-specific ubiquitin C-terminal hydrolase, demonstrated selective localization of the immunoreactivity in a synoviocyte population different from acid phosphatase-positive Type A synoviocytes. The immunoreactive cells were lined up in the synovial intima and extended dendritic processes towards the joint cavity to form a dense plexus on the surface. Electron microscopic examination clearly identified the PGP 9.5-immunoreactive cells as Type B synoviocytes characterized by developed rough endoplasmic reticulum and free ribosomes. Immunoreactivity for PGP 9.5 was diffusely distributed throughout the cytoplasm, including the tips of fine processes. Western and Northern blot analyses could not distinguish the corresponding protein and mRNA obtained from the brain and synovial membrane. The existence of the neuron-specific PGP 9.5 in Type B synoviocytes suggests a common mechanism regulating the protein metabolism between neurons and synoviocytes, and also provides a new cytochemical marker for identification of the cells.     

Submicroscopic organization of M. pneumoniae studied by means of negative contrasting, ultrathin sections and scanning electron microscopy]

The ultrastructure of M. pneumoniae, grown on a solid culture medium and in a liquid one, was studied by a number of methods. Two types of cells were shown to prevail in the culture: spherical cells (0.5--1 micrometer) forming chains of different configurations and filamentous cells (5 micrometer long and greater) with spherical enlargements along their whole length. The absence of microcapsules made M. pneumoniae different from other species of mycoplasms, and the organism proliferated by division into 2 daughter cells, equal or unequal in size, by the segmentation of the cytoplasm and the formation of elementary bodies inside the cell and on its surface.     

Evaluation of structural changes induced by high hydrostatic pressure in Leuconostoc mesenteroides

Scanning electron microcopy (SEM), transmission electron microscopy (TEM), and differential scanning calorimetry (DSC) were used to evaluate structural changes in Leuconostoc mesenteroides cells as a function of high-hydrostatic-pressure treatment. This bacterium usually grows in chains of cells, which were increasingly dechained at elevated pressures. High-pressure treatments at 250 and 500 MPa also caused changes in the external surface and internal structure of cells. Dechaining and blister formation on the surface of cells increased with pressure, as observed in SEM micrographs. TEM studies showed that cytoplasmic components of the cells were affected by high-pressure treatment. DSC studies of whole cells showed increasing denaturation of ribosomes with pressure, in keeping with dense compacted regions in the cytoplasm of pressure-treated cells observed in TEM micrographs. Apparent reduction of intact ribosomes observed in DSC thermograms was related to the reduction in number of viable cells. The results indicate that inactivation of L. mesenteroides cells is mainly due to ribosomal denaturation observed as a reduction of the corresponding peak in DSC thermograms and condensed interior regions of cytoplasm in TEM micrographs.     

The fine structure of elongate gametocytes of Leucocytozoon ziemanni (Laveran).

In an effort to establish comparative data within the genus Leucocytozoon, elongate gametocytes of L. ziemanni from naturally infected great horned owls (Bubo virginianus) were examined by electron microscopy. Micro- and macrogametocytes proved to be easily distinguishable at the electron microscopic level due to dramatic dimorphism at maturity and cytoplasmic and nuclear morphology. The parasite membrane architecture, number and type of cytoplasmic ribosomes of both micro- and macrogametocytes, presence and arrangement of osmiophilic bodies and electron dense spheres, mitochondrial morphology, endoplasmic reticulum cisternae morphology, mitochondria containing pocket infoldings of the nuclear membrane of the microgametocytes, and cytostome and food vacuole formation compare favorably with available information on L. simondi and L. smithi. Comparative variations exist only in that L. ziemanni gametocytes apparently lack compartmentalization of the cytoplasm by aligned unit membranes and parasite induced separations of the host cell nucleus as reported for L. simondi.     

Flagellar systems in the euglenoid flagellates

The flagellar apparatus of euglenoids consists of two functional basal bodies, three unequal microtubular roots subtending the reservoir, and a fourth band of microtubules nucleated from one of the flagellar roots and subtending the reservoir membrane. The flagellar apparatus of some euglenoids may contain additional basal bodies, striated roots ("rhizoplasts"), fibrous roots, striated connecting fibers between basal bodies, layered structures, or various electron-dense connective substances. With the possible exception of Petalomonas cantuscygni, nearly all euglenoids are biflagellate although the length of one flagellum may be highly reduced. The flagellar transition zone and number of basal bodies are highly variable among species. In recent years a cytoplasmic pocket that branches off from the reservoir has been discovered. The microtubules of the ventral flagellar root are continuous with the microtubules which line this pocket. Based on positional and structural similarities, this structure is believed to be homologous with the MTR/cytostome of bodonids. Coupled with other ultrastructural and biochemical data, the fine structure of the flagellar apparatus supports the belief that the euglenoid flagellates are descendant from bodonid ancestors.     

Evaluation of Structural Changes Induced by High Hydrostatic Pressure in Leuconostoc mesenteroides

Scanning electron microcopy (SEM), transmission electron microscopy (TEM), and differential scanning calorimetry (DSC) were used to evaluate structural changes in Leuconostoc mesenteroides cells as a function of high-hydrostatic-pressure treatment. This bacterium usually grows in chains of cells, which were increasingly dechained at elevated pressures. High-pressure treatments at 250 and 500 MPa also caused changes in the external surface and internal structure of cells. Dechaining and blister formation on the surface of cells increased with pressure, as observed in SEM micrographs. TEM studies showed that cytoplasmic components of the cells were affected by high-pressure treatment. DSC studies of whole cells showed increasing denaturation of ribosomes with pressure, in keeping with dense compacted regions in the cytoplasm of pressure-treated cells observed in TEM micrographs. Apparent reduction of intact ribosomes observed in DSC thermograms was related to the reduction in number of viable cells. The results indicate that inactivation of L. mesenteroides cells is mainly due to ribosomal denaturation observed as a reduction of the corresponding peak in DSC thermograms and condensed interior regions of cytoplasm in TEM micrographs.     

POLYRIBOSOMES AND CISTERNAL ACCUMULATIONS IN ROOT CELLS OF RADISH

The zone of root hair formation of seedling radish roots, Raphanus sativus L., was studied by phase-contrast and electron microscopy. Localized dilations of the endoplasmic reticulum, which contained a moderately dense proteinaceous material, were found to be a common component of the cytoplasm in cells of the epidermis and cortex. The surfaces of these dilations were covered with polyribosomes in discrete coils commonly composed of 15 to 17 ribosomes. The function of these structures and the fate of the material accumulated in them are unknown. Their similarity to structures described in some types of animal cells is discussed.     

Neuroglia in the corpus callosum of the primate, slow loris (Nycticebus coucang coucang)

The corpus callosum of adult slow loris consists of a mixed population of several cell types, i.e. free subependymal cells, oligodendrocytes, astrocytes and microglia. The free subependymal cell is rather small and slender with a somewhat patchy nucleus. It shows scanty cytoplasm with free ribosomes. Oligodendrocytes vary both in nuclear and cytoplasmic densities and can be divided into three classes: light, medium dense and dark types. Their cytoplasm contains microtubules, rough endoplasmic reticulum and Golgi saccules. Astrocytes are pale cells with large amount of filaments in their cytoplasm. Microglia are small cells with granulated nuclei. The cells often show large cytoplasmic protrusions containing the usual cell organelles and lipofuscin bodies in their cytoplasm. Lastly, cells with typical features of neurons are occasionally encountered among the white matter.     

The histochemistry and infrastructure of the coelomocytes of species of Lumbricillus, and observations on certain other enchyfraeid genera (Oligochaeta: Annelida)

The main coelomocyte type–the granular mucocyte–of Lumbricillus mirabilis, L. reynold-soni and L. rivalis has inclusions consisting of a mucopolysaccharide-protein complex with very low lipid levels. Both neutral and carboxylated acid mucopolysaccharides occur, the latter predominating in the granules of L. rivalis in which protein levels are lower than in the other two species.
The Golgi-derived granules of the mucocytes of L. mirabilis and L. reynoldsoni are electron dense when mature and are separated from each other by cytoplasm housing, generally, a single endoplasmic reticulum profile. The mucocytes arise from the peritoneum. In L. rivalis the inclusions are of finely fibrillar material typical of acid mucopolysaccharides. Studies on species of other genera show the species of littoral origin to possess mucocytes with an ultrastructure similar to that of the littoral L. mirabilis and L. reynoldsoni ; those of non-littoral origin are similar to the non-littoral L. rivalis. The differences therefore appear to be eco-physiological rather than taxonomic.
Amoebocytic coelomocytes occur and two types are described for L. mirabilis and L. reynoldsoni. Type I is finely pseudopodous and contains numerous small, electron dense inclusions. The origin of Type I from the peritoneum is demonstrated. Type II is characterized by fewer pseudopodia and large, electron dense inclusions similar to chloragosomes. Pinocytotic vesicles occur at the cell periphery. No intermediates between Type I and II were observed, and Type II was not seen in L. rivalis. Both types occur in Enchytraeus albidus , but only Type I in Fridericia bulbosa and no amoebocytes were observed in Mesen-chytraeus sp.     

The Fine Structure of Trypanosoma congolense in Its Bloodstream Phase

SYNOPSIS. The fine structure of 2 isolates of Trypanosoma congolense maintained in laboratory rodents has been studied from thin sections of osmium- and aldehyde-fixed flagellates. The pellicular complex, nucleus, and flagellar apparatus are all similar to those of other African trypanosomes. Aberrant intracellular differentiation of the flagellum is occasionally found. As in bloodstream forms of other salivarian trypanosomes the single mitochondrion forms an irregular canal running from one end of the body to the other, with a shallow bowl-shaped expansion forming a capsule for the fibrous kinetoplast (mitochondrial DNA). A connexion between the mitochondrial envelope of the kinetoplast and the basal body of the flagellum is not evident, and sometimes the flagellum base is not even apposed to the kinetoplast but lies behind it. Tubular cristae are present in the mitochondrial canal and, by light microscopy, this structure gives a positive reaction for NAD diaphorase suggesting at least some activity in electron transport, even tho at this stage in its life cycle respiration is doubtfully sensitive to cyanide and cytochrome pigments are in all probability absent. The region of the cytoplasm between the nucleus and the flagellar pocket has all the trappings associated with secretory cells in higher animals, or with the secretion of surface structures in phytoflagellates. just behind the nucleus a limb of granular reticulum subtends a Colgi stack of flattened saccules with attendant vesicles. Close to the distal pole of the Golgi complex is a network of smooth-membraned cisternae, termed here the agranular or secretory reticulum, which undergoes localized swelling with the accumulation of a secretory product to form large spherical sacs or vacuoles. These network-linked vacuoles probably correspond to the post nuclear vacuole complex visible by light microscopy. From its apparent secretory function this complex is regarded here as being possibly an extension or derivative of the Golgi complex, the smooth-membraned tubules lying alongside the 2 structures possibly representing a link between them. By analogy with phytoflagellates and the secretory cells of higher animals, it is suggested that the secretion is transported for discharge into the flagellar pocket by way of multivesicular bodies and smooth-walled tubules or vesicles. Spiny pits in the wall of the flagellar pocket, and similar-sized vesicles in the nearby cytoplasm, could be stages in either exocytosis of secretion or endocytosis (pinocytosis). It is tentatively suggested that the secretion may be the material from which the surface coat is formed. Neither a cytostome nor a contractile vacuole has been observed in T. congolense.     

Fine Structure of Trypanosoma cyclops in Noncellular Cultures*

The fine structure of the epimastigotes of Trypanosoma cyclops maintained in blood agar medium at 25 C is described. This organism was isolated from the Malaysian primates Macaca nemestrina and Macaca ira. A distinctive feature of T. cyclops is that it is pigmented when grown in the presence of hemoglobin. The pigment bodies apparently lack a substructure and are electron dense even in unstained sections. Most of the pigment is located posterior to the kinetoplast region but some is found adjacent and anterior to the kinetoplast. Cells from control cultures grown in medium lacking hemoglobin did not possess this type of pigment body. Similarly, pigment was not found in cells of an Indonesian trypanosome grown in medium containing hemoglobin. The cytoplasm of T. cyclops is bounded by a unit membrane which is specialized where it makes contact with the flagellum. A cytostome extends from the region of the flagellar pocket. The kinetoplast and nucleus are immediately posterior to the base of the flagellum. Transverse sections in the region of the flagellar pocket and flagellar base often reveal a group of 3 microtubules which are distinct from the pellicular microtubules.     

Le spermatozoide de Ophidion sp. (Poisson,téléostéen): Particularités ultrastructurales du flagelle

The spermatozoon of Ophidion sp. possesses an elongated nucleus 8 μm long, a short midpiece (0,6 μm), and a long flagellum (100 μm). The flagellar membrane extends in the form of two diametrically opposed sidefins. Evolving spermatids and spermatozoa are found in the lumen of the seminiferous tubes. The sections of flagella show filamentary and tubular elements disposed parallel to the axoneme microtubules. We have divided the flagella into three types. In type 1 the tip of the sidefins contains 20 to 30 filaments 5 run in diameter and between these and the axoneme 20 to 30 tubular elements 15 to 20 nm in diameter. Type 2 possesses a dense cytoplasm and a few tubular elements 10 nm in diameter disposed at the tip of the sidefins. Type 3 contains a cytoplasm which is not dense and in which we found polysaccharides and 1 to 8 tubular elements forming a palisade which lines the plasma membrane at the tip of the sidefins. We interpret these three types as three successive stages in the organization of the flagellum during spermiogenesis. Type 3 corresponds to the spermatic flagellum. These 10-nm-diameter tubules do not have the same chemical composition as the microtubules. Elements of the cytoskeleton serve as a support for the sidefins.