bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Ultrastructure of the Plumula of the Tooth of Lytechinus variegatus (Echinodermata: Echinoidea)
Authors: Chen Chang‐Po , Lawrence John M. 
Published: April 2010

AbstractThe plumula is enclosed by a single layer of epithelial cells. There are two types of odontoblasts: syncytial and free odontoblasts. Syncytial odontoblasts are arranged linearly on the abaxial side and have a highly active Golgi complex, rough endoplasmic reticulum, large and round mitochondria, and small coated vesicles indicative of a high level of secretory activity. Free odontoblasts cluster on the adaxial side and have patchy chromatin and little cytoplasm. The free odontoblasts migrate to the abaxial side, where their structure changes to that of syncytial odontoblasts. Calcareous deposits are formed intracellularly by syncytial odontoblasts within two membranes: an outer plasma membrane and an inner vacuolar membrane. The vacuolar membrane has organic particles on the surface of the membrane. There is no trace of organic matter within the calcareous deposit. Fibroblasts are located on the adaxial side. Collagen fibers are located primarily on the adaxial side adjacent to the calcareous depositing membranes and between free odontoblasts, but they are not located in the deposits. Collagen fibers may play a role in cell migration and thus in calcification. The morphological changes of the plumulae are closely related to calcification.
The Ultrastructure of the Gastrodermal Gland Cells in the Freshwater Planarian Dugesia gonocephala s.l.
Authors: Garcia‐Corrales Pedro , Gamo Jacinto 
Published: April 2010

AbstractLight and transmission electron microscopy have been used to study the gastrodermal gland cells of the triclad Dugesia gonocephala s.l. The events involved in the ultrastructural transformation and the secretion process in these cells were followed at four different stages in both fasted and fed animals. During the feeding stage their secretory granules are directly discharged into the intestinal lumen by means of a secretion process of the holocrine type that is described in this paper. It is suggested that such secretions contribute to extracellular digestion and that disintegration of the gland cells is accompanied by a differentiation of neoblasts into new gland cells, reflecting a turnover of gland cells during the triclad digestive stages.
Ultrastructural Aspects of the Endolymphatic Organ in the Frog Rana esculenta
Authors: Marmo Francesco , Balsamo Giuseppe , Crispino Paola 
Published: April 2010

AbstractMorphological evidence indicates that the endolymphatic sac of anuran amphibians is involved in the morphogenesis of most statoconia (aragonite crystals). The cells frequently show the aspect of an intense secretory activity, their cytoplasm being totally occupied by a number of vesicles the contents of which might be expelled into the lumen forming the organic—or at times mineral—components of statoconia. Moreover, evidence is presented that another function of the endolymphatic sac might be involvement in a resorptive mechanism for endolymph and for CaCO3 mobilization from aragonite crystals. In fact, these show clear signs of erosion, consistent with a role as a labile calcium deposit played by the calcareous formations of the endolymphatic sac.
Fine Structure of the Fat Body and its Bacteroids in Blattella germanica (Blattodea)
Authors: De Piceis Polver Paola , Sacchi Luciano , Grigolo Aldo , Laudani Ugo 
Published: April 2010

AbstractThe abdominal fat body of the cockroach Blattella germanica contains three characteristic cell types—trophocytes, bacteriocytes and urate cells—which have been investigated by electron microscopy. The trophocytes are rich in lipid droplets of different sizes; glycogen, rough endoplasmic reticulum and mitochondria are also abundant. In females immediately after eclosion, the trophocytes contain a greater number of lipid droplets, some of which have different electron density; glycogen and cytoplasmic organelles are clearly reduced. The bacteriocytes hold rod‐like and spherical bacteroids, which are encapsulated by a vacuolar membrane; they show a thin cytoplasmic membrane and an evident cell wall surrounded by a membrane‐like outer envelope. The bacteroids appear to be dividing either by transverse partition or by budding. The urate cells, adjacent to the bacteriocytes, are characterized by complex urate vacuoles delimited by a double layer‐structure.
Fine Structural Observations on the Extracellular Matrix (ECM) of Xenoturbella bocki Westblad, 1949
Authors: Pedersen Knud Jørgen , Pedersen Lars Ryde 
Published: April 2010

AbstractFine structural observations on the extracellular matrix (ECM) and connective tissue system of the enigmatic vermiform animal Xenoturbella bocki have demonstrated a complex and interesting organization of the ECM. Most conspicuous is the subepidermal membrane complex (SMC), and the major part of the ECM is present in this structure, which consists of a limiting basal lamina on each side of a central thick filamentous layer, probably of a collagenous nature. Distinct anchoring filaments are found as part of the SMC. A basal lamina is also observed in connection with the gastrodermal cells. The mesoderm is represented by a loose, ill‐defined parenchyma, without filaments. The SMC is discussed in relation to subepidermal basal matrices occurring in turbellarians and enteropneusts, the two groups to which a relationship to Xenoturbella previously has been suggested. Comparisons between the ECM in Xenoturbella and in turbellarians do not support the notion of a relationship between these groups. Conversely, the present study strengthens previous indications of distinct similarities between certain characteristics of the epidermis and the SMC present in both enteropneusts and in Xenoturbella.
Fine Structure of Spermatozoa in Perkinsiana rubra and Pseudopotamilla reniformis (Sabellidae: Polychaeta)
Authors: Chughtai Iffat 
Published: April 2010

AbstractThe Perkinsiana acrosome is elongated, pointed and tapering, strengthened anteriorly by cortical rings of longitudinally running units. The Pseudopotamilla acrosome is cap‐like and its apical region contains a laminar body with two electron densities, the laminae crossed by occasional lines of dislocation, as in a crystal. These apparently solid regions are closely followed by peripherally situated lucent zones. The zone in Pseudopotamilla contains tubules, which are very like those in Sabella sperm, except that they lack connections with the acrosome base. Both species are probably broadcast spawners and have nuclei, mitochondria, centrioles and flagella of the primitive type. This may, however, be a secondary reversion through neoteny.
A Scanning Electron Microscope Study on the Internal Structure of the Peritreme of the Female Mite Varroa jacobsoni (Oudemans, 1904)
Authors: Liu T. P. 
Published: April 2010

AbstractThe peritreme of the adult female mite Varroa jacobsoni is located laterally above coxa III and is enclosed within a peritrematal shield which has a slit at the end. The peritrematal shield is cuticular in nature. The peritreme is lined with a thick inner membrane which has numerous tooth‐like projections. The outer membrane of the peritreme is thin and smooth. In between these two membranes is a layer of columnar cells. The internal structure of the peritreme in relation to the female mite's ability to adjust to different atmospheric conditions is discussed.
Phagocytic Cells in the Peripheral Blood of the Dogfish Scyliorhinus canicula L. II. In Vivo Studies
Authors: Parish N. , Wrathmell A. , Hart S. , Harris J. E. 
Published: April 2010

AbstractIn vivo phagocytosis by peripheral blood leucocytes of the dogfish Scyliorhinus canicula L. was examined by monitoring the fate of a variety of injected materials, both particulate and soluble, in normal and immunised fish. Carbon, yeasts and bacteria were phagocytosed by monocytes, thrombocytes and type 1 granulocytes (neutrophils). Quantitative in vivo antigen clearance studies employed five species of bacteria, yeast and KLH. After an initial significant decrease of these antigens in the circulation, low numbers of viable bacteria and yeasts and low concentrations of KLH persisted for long periods after injection. Previous exposure to several of these antigens had little or no effect.
A Motorneurone Cell Body Located Either Dorsally or Ventrally within a Crustacean Abdominal Ganglion
Authors: Maitland D. P. , Heitler W. J. 
Published: April 2010

AbstractIn the last abdominal ganglion of the squat lobster Galathea strigosa (Decapoda, Anomura) a unique pair of flexor motorneurones exist whose medial cell bodies occur paired either on the ventral or the dorsal surface of the ganglion or else are located separately, one dorsal and the other ventral. In 60 squat lobsters (30 ♂ 30 ♀), this pair of medial dorsal/ventral (MDV) cell bodies was found in 4 distinct cell pair configurations: ventral/ventral, 24; dorsal/dorsal, 5; right ventral/left dorsal, 14; right dorsal/left ventral, 17. MDV cell bodies were never found lying midway between the dorsal and ventral surfaces. The distribution of configurations was approximately the same for both sides of the ganglion and for both sexes, and whether a cell occurred ventrally or dorsally was found to be independent of the position of its partner. The determination of cell body location appears not to be influenced by any cell‐cell interaction, despite an apparent ‘point of close association’ between the two soma neurites and a strong bias overall towards the ventral location (dorsal 1/3, ventral 2/3).
The Ultrastructure of the Protonephridium of the Actinotroch Larva (Phoronida)
Authors: Hay‐Schmidt Anders 
Published: April 2010

AbstractThe actinotroch larva of Phoronis muelleri has a pair of protonephridia located beneath the tentacle ring and draining the blastocoel; each protonephridium is composed of about 25 solenocytes and a nephroduct which opens in a nephropore on the ventral side of the metasome. The neck of the solenocytes consists of bars, mutually interconnected by a fenestration lamina. Inside the neck microvilli originate proximally in the proximal intrachoanal field and extend through the neck into the nephroduct. There is no canal cell. In cross section the nephroduct is composed of 5–7 monociliary cells, with the cilium protruding through a border of microvilli and extending into the nephroduct. The whole protonephridium is surrounded by a basal lamina. Comparisons of the actinotroch protonephridium with those of other groups have not revealed any convincing homologies. The protonephridia of the protostomians are all considered to be of ectodermal origin, while the cyrtopodocytes of Branchiostoma are mesodermal. The protonephridium of the actinotroch is ectodermal.
Differential Effect of Sodium and Magnesium on the Pituitary of Goldfish Adapted to Calcium‐Free Environments
Authors: Olivereau Madeleine , Olivereau Jean‐Michel , Lambert Jean‐François 
Published: April 2010

AbstractAdaptation to deionized water (DW) affects several cell types in the goldfish. The pars intermedia PAS‐positive cells are highly stimulated. Their low response or the absence of changes in goldfish kept in 1/3 Ca‐free seawater (SW) and in Ca‐free SW‐adapted eels, respectively, suggest that sodium and/or magnesium are interfering. To test this hypothesis, young goldfish were adapted to DW supplemented or not with sodium (50 and 140 mM) for 8 and 16 days or with magnesium (16.5 and 50 mM) for 16 and 30 days. Cytological and morphometric studies of the pituitary showed that prolactin (PRL) cell activity was reduced by sodium. Thyrotropic (TSH) cells were stimulated. The activity of melanocyte‐stimulating (MSH) cells increased in DW + Na+. Stimulation of the pars intermedia PAS+ cells in DW was partly inhibited by adding sodium; the cellular and nuclear areas increased only moderately, the endoplasmic reticulum (ER) was not conspicuous and mitotic activity disappeared.In DW + Mg2+ the activity of PRL, TSH and MSH cells tended to be lower after a long‐term adaptation. The response of the PAS+ cells was as high as that noted in DW; complete degranulation, enlargement of the ER and important mitotic activity. Differential responses to Na+ and Mg2+ are not due to pH differences in the solutions.External sodium is able then to reduce the response of the PAS+ cells in a Ca‐free environment, while magnesium is not inhibitory. Other cell types are also affected by high levels of Na+ and Mg2+.
Tunicate Endostyles: Histochemistry of Acidic Glycoproteins Re‐examined in Ciona intestinalis and Styela plicata
Authors: Hohenleitner Frank J. , Caso Louis V. 
Published: April 2010

AbstractPrevious reports of tunicate endostyles have suggested that they contain little or no acidic glycoproteins in the glandular zones. The endostyles of Ciona intestinalis and Styela plicata were examined after anhydrous fixation with cyanuric chloride. Polyanions were stained with alcian blue (AB) at pH 2.5 or azure A, while sulfomucins were stained with high‐iron diamine (HID) or AB at pH 1.0. Endostyles were also tested for sensitivity to acid hydrolysis (AH) and saponification. In Ciona zones 2 and 4 sometimes demonstrated positive HID and AB 1.0 responses. Almost invariably zone 6 was AB+ at pH 2.5; zones 2 and 4 were frequently responsive to AB, but less intense. Each of these 3 zones, when AB+, was sensitive to AH. Responses by zones 3 and 5 to AB (pH 2.5), azure A and saponification suggest that these zones contain mostly nuclear material. In secretory zones 2, 4 and 6 histological responses are consistent with the histochemistry of sialomucins. Zones 1 and 8 had sulfated material in the apical edges in both animal groups. Among the fixatives used for Ciona, only anhydrous fixation demonstrated most of the positive responses to polyanion‐sensitive stains.
Estrogens in Plasma of the Hagfish, Myxine glutinosa (Cyclostomata)
Authors: Schützinger S. , Choi H.S. , Patzner R.A. , Adam H. 
Published: April 2010

AbstractConcentrations of estrogens in the plasma of Myxine glutinosa were measured in an attempt to determine whether different stages of reproduction are connected with certain levels of steroid concentration. After extraction with diethylether and column chromatography on Sephadex LH‐20, the plasma was radioimmunoassayed for estrogens. Samples were subdivided into 9 groups according to the gonadal conditions of the animals. There appears to be a positive correlation in females between plasma estrogen concentration and egg size (taken as an indication of reproductive stage). After ovulation the level of plasma estrogens fell appreciably. Estrogen levels of most of the samples from male animals were also determined.
Ultrastructure of Adult Gonads and Development and Structure of the Larva of Rhabdopleura normani (Hemichordata: Pterobranchia)
Authors: Lester Susan M. 
Published: April 2010

AbstractSexually mature adults, embryos and larvae of the pterobranch Rhabdopleura normani from Bermuda were studied with light and electron microscopy. The sexes are separate among the zooids of a colony, but a given colony may contain females and males. In zooids of either sex the single gonad is associated with a large haemal sinus in the trunk sac and is displaced laterally (to the right or to the left). The wall of the gonad is composed of three layers: an outer metasomal peritoneum, an internal lining of germinal epithelium and an intervening genital haemal sinus. The mature gametes lie in the lumen within the gonad. The spermatozoon is characterized by an elongate nucleus, no obvious acrosome, a long mitochondrial filament in a midpiece appendix and a single flagellum with a 9+2 axoneme. Females brood 200 μm eggs and embryos in their distinctive, basally coiled tubes. The yolky eggs undergo radial cleavage and develop into ciliated, lecithotrophic, oblong larvae (400 μm in length) that are characterized by: (1) yellow coloration peppered with black pigment spots; (2) a deep ventral depression; (3) a posterior adhesive organ; (4) an anterior apical sensory organ; (5) an evenly ciliated epitdermis. The ventral depression is not invaginating endoderm, but is instead a glandular epithelium that evidently secretes the larval cocoon and the adult tube. Internally, the peritoneum of the coelomic cavities begins to split from the periphery of a large, central mass of yolky mesenchyme cells. The larva swims using cilia, but also undergoes contractions, evidently powered by the peritoneal cells, which constitute a myoepithelium. The discussion considers pterobranch affinities with other deuterostomes and with lophophorates.
Ultrastructure of Cytotoxic Cells in Frogs
Authors: Smith C. T. , Ghoneum M. , Cooper E. L. 
Published: April 2010

AbstractOur previous work gave evidence that leopard frogs (Rana pipiens) possess inducible killer (IK) cells (CTL‐like) and spontaneous killer (SK) cells (NK‐like) that can destroy allogeneic RBC. To further characterize these cytotoxic cells we have examined their ultrastructural morphology and effector cell‐target cell membrane contacts. We also studied the sensitivity of these two effector cells to low temperature (4°C). Our results showed that SK effector cells are lymphocytes (10 μm) which contain numerous vacuoles and osmiophilic granules, while IK effectors are another lymphocyte population (up to 12 μm) with a small amount of cytoplasm and few mitochondria. Both IK‐ and SK‐mediated lytic responses were suppressed significantly by low temperature. These observations allow us to propose that frog SK and IK cells may be homologous to mammalian NK and CTL.
Ultrastructural Study of Haemocytes of the Freshwater Snail Planorbarius corneus (L.) (Gastropoda, Pulmonata)
Authors: Ottaviani Enzo , Franchini Antonella 
Published: April 2010

AbstractUltrastructural studies were performed on the blood cells of Planorbarius corneus. Spreading and round cell forms were observed. The spreading form can be distinguished from the round form by its abundant cytoplasm, pseudopods and irregularly shaped nucleus. Electron dense granules in the mitochondrial matrix are found in the round form and are lacking in the spreading form. Moreover, cellular apoptosis is observed in the round form. The ultrastructural findings and the previously described characteristics support the idea that the two cell forms belong to two basic cell types.
In vitro Excystation of Metacercariae of Clinostomum complanatum (Rudolphi, 1819) (Digenea: Clinostomatidae)
Authors: Kalantan A. M. N. , Arfin M. 
Published: April 2010

AbstractIn vitro excystation of metacercariae of Clinostomum complanatum (Rudolphi, 1819) was studied. Excystation was an active process, initiated by a rise in temperature. The metacercariae excysted in enzymic as well as non enzymic medium, but the rate of excystation was affected by the temperature and/or pH of the medium. The optimal excystation was obtained in pepsin‐Tyrode at pH 2.3‐3.5 and a temperature of 42°C. Trypsin treatment was not required.
Autoradiographic Investigations on Cell Proliferation in the Digestive Mucosa of Fishes
Authors: Kiss Robert , de Launoit Yvan , Lenglet Georges , Danguy Andre 
Published: April 2010

AbstractThe labelling index (TLI) of the digestive mucosa of some fish species was determined following a pulse labelling with tritiated thymidine ([3H]TdR) and light microscopic autoradiography. In the oesophageal epithelium, proliferation was observed to occur in non mucus‐secreting cells. In the intestine, both undifferentiated and absorptive cells incorporated [3H)TdR within 1 h after injection. Statistically significant differences in [3H]TdR incorporation were observed between the upper intestine region and both the middle and lower parts on the one hand, and between the middle and lower parts on the other hand. Mucus‐secreting cells seemed unable to proliferate. In the stomach, significantly fewer labelled nuclei were counted; they were located in the isthmus epithelium. No significant difference was observed between the TLI of these regions in the different species.
Cypris Ultrastructure, Metamorphosis and Sex in Seven Families of Parasitic Barnacles (Crustacea: Cirripedia: Rhizocephala)
Authors: Glenner H. , Høeg J. T. , Klysner A. , Larsen B. Brodin 
Published: April 2010

AbstractCypris morphology in the Rhizocephala differs both between the sexes of individual species and between the species. The large aesthetasc on the third antennular segment is unique to male cyprids of the Lernaeodiscidae, Peltogasteridae and Sacculinidae (suborder Kentrogonida) and Mycetomorpha vancouverensis (suborder Akentrogonida). A fourth segmental aesthetasc, common to both sexes, is much longer in males than in females. A spinous process on the attachment disc is another male‐specific character, but is absent altogether in the Lernaeodiscidae.It is argued that these aesthetascs help locate the settlement targets.Except in Mycetomorpha vancourverensis, aesthetascs have been secondarily lost in cyprids of the suborder Akentrogonida, and there are no other morphological means for separating the male and female settling stage. In cyprids of Sylon hippolytes (Sylonidae) and of Mycetomorpha vancouverensis and Thompsonia sp. (Akentrogonidae) the long and slender antennules are probably used in penetration without formation of a kentrogon, as already reported for Clistosaccus paguri (Clistosaccidae). Cyprids of Sylon hippolytes and Clistosaccus paguri are almost morphologically identical.
Cirral Structure of the Pedunculated Marine Barnacle Lepas anatifera L. (Crustacea, Cirripedia) — I. Ultrastructure of the Neuromuscular Apparatus
Authors: Pfeiffer C. J. , Lowe K. J. 
Published: April 2010

AbstractLepas anatifera L. is a common pedunculated marine barnacle with well developed, articulated cirri which gather water‐suspended food particles, aid in predatory food capturing and may facilitate respiratory function by creating water currents through the mantle. The present data are the first ultrastructural findings of the neuromuscular apparatus which supports rhythmic cirral contraction.A single large striated flexor muscle extending the length of the cirus contains mostly one type of myofibril (Type A) but is accompanied by a small band of more compact myofibrils (Type B). A well developed T‐tubular system with extensive sarcoplasmic cisternae and dyads is found, in addition to subsarcolemmal membranous whorls. A central neural complex innervates this muscle and electron‐lucent axons containing large membranous elements and small vesicles and surrounded by supporting cells with extensive rough endoplasmic reticula are present. Intimate association of nerve processes with the flexor muscle consists of neuromuscular junctions with synaptic‐type vesicles, and a well developed mode of sarcolemmal vesicular transport. These focally compacted vesicles communicate directly with the muscle tubular system. Rhythmic movement of cirri is probably controlled by alternating contraction of the flexor muscle followed by relaxation with pulsatile filling of the afferent hemocoel with blood.