1,720,957 research outputs found
Histology and histochemistry of the albumin glands in some foam-nesting anurans
Full text linkThis study deals with the histology and histochemistry of the oviducts of three species of frogs that lay their eggs embedded in a foam nest (Leiuperidae: Physalaemus biligonigerus and Pleurodema borellii; Leptodactylidae: Leptodactylus chaquensis). In all of them the oviducts show five sections [in cephalic-caudal direction, the Pars Recta (PR), Intermediate Proximal Zone (IPZ), Preconvolute Part (PCP), Convolute Part (CP) and Ovisac (O)] identifiable on anatomical and histological basis, and on the peculiarities of their secretions and joined biomolecules. In the section encompassed between the distal portion of PPC and O of the three species it was possible to identify glandular areas that produce glycoconjugates with a dominance of proteins joined to lipids or to glucids that constitute the precursor of the foam. These histologically differentiated glandular aggregations, not yet recorded in species with other modes of oviposition, are named here as “albumin glands”.Fil: Alcaide, MaríaF.. Fundación Miguel Lillo; ArgentinaFil: Lavilla, Esteban Orlando. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico - Tucumán. Unidad Ejecutora Lillo; ArgentinaFil: Pucci Alcaide, Ana. Fundación Miguel Lillo; Argentin
Testicular histology of Anurans that deposit eggs out of the water
Full text linkAnuran amphibians show the largest diversity of amphibian reproductive modes,many of which imply egg deposition out of the water. This kind of egg depositionrequires specialisations to avoid egg desiccation. Physiological, anatomical and ethological traits integrate to define these modes. In particular, morphological featuresof the urogenital system correlate with these reproductive modes and the environmental conditions where egg-laying occurs. In this study, we describe the testicularhistology and spermatogenesis of the nest-building frog Leptodactylus latinasus, andwe compare it with other species that breed out of water. We found variations in testis size, the thickness of interstitial tissue, tunica albuginea, and peritubular tunics,flagellum length, and in the shape and size of the spermatozoal nucleus. Certainspecifics? characters differed at the species level, but not between families. Suchvariation could be an indicator of spermatozoal performance and environmentalconstraints under which fertilisation takes place.Fil: Pucci Alcaide, Ana. Instituto de Morfología Animalfundación Miguel Lillotucumán; ArgentinaFil: Pucci Alcaide, Franco Jose. Instituto de Morfología Animalfundación Miguel Lillotucumán; ArgentinaFil: Michel, Adriana Azucena. Instituto de Morfología Animalfundación Miguel Lillotucumán; ArgentinaFil: Ponssa, María Laura. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico - Tucumán. Unidad Ejecutora Lillo; Argentin
The Vesicles of Phyllomedusa sauvagii (Anura: Hylidae) Nest
Full text linkPhyllomedusa sauvagii lays its eggs surrounded by peculiar vesicles in nests made with tree leaves and, until now, the function of these vesicles was thought to be for maintaining moisture. The histomorphological and histochemical analysis of the oviduct of individuals in ovulatory period, and the study of the vesicles in the oviduct, ovisac and in the nest, showed unexpected results. Vesicles originate from glycoconjugates, proteins and lipids secreted in the PCP and PC and organized in the oviductal lumen and, according to their content, it is possible to recognize at last four types. Furthermore, both in the ovisac and in the nest, vesicles show peculiar relationships with oocites/eggs/embryos through specific communication channels, showing the existence of more complex interactions than previously thought.Fil: Pucci Alcaide, Ana. Fundación Miguel Lillo; ArgentinaFil: Alcaide, María Fernanda. Fundación Miguel Lillo; ArgentinaFil: Pucci Alcaide, Franco. Fundación Miguel Lillo; ArgentinaFil: Lavilla, Esteban Orlando. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán; Argentina. Fundación Miguel Lillo; Argentin
Morphometric Variations in the Skin Layers of Frogs: An Exploration Into Their Relation With Ecological Parameters in Leptodactylus (Anura, Leptodactylidae), With an Emphasis on the Eberth-Kastschenko Layer
Full text linkLeptodactylus is a genus of frogs known to live in diverse habitats and to show both aquatic and terrestrial breeding habits. We studied 21 species of Leptodactylus to explore whether skin structure specialization relates to habitats and habit variation. Morphometric analyses of the skin thickness revealed that phylogeny has a strong influence on variations in the thickness of the epidermis, stratum spongiosum, Eberth-Kastschenko layer, and stratum compactum, while habitat and habits display no significant correlation. The optimization of the phylogenetic hypothesis suggested that a pattern of intermediate values for skin layer thickness are plesiomorphic for this group. Anat Rec, 2017. © 2017 Wiley Periodicals, Inc. Anat Rec, 300:1895–1909, 2017.Fil: Ponssa, María Laura. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico - Tucumán. Unidad Ejecutora Lillo; ArgentinaFil: Barrionuevo, Jose Sebastian. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales “Bernardino Rivadavia”; ArgentinaFil: Pucci Alcaide, Franco. Fundación Miguel Lillo; ArgentinaFil: Pucci Alcaide, Ana. Fundación Miguel Lillo; Argentin
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
HISTOLOGíA DEL OVARIO Y OVIDUCTO DE LA RANA DE DESARROLLO DIRECTO Oreobates discoidalis (ANURA: STRABOMANTIDAE)
Full text linkOreobates discoidalis es un anuro que se reproduce en entornos húmedos y protegidos, depositando sus huevos relativamente grandes directamente en tierra y exhibiendo desarrollo directo. En este estudio, se describe la histología de los órganos sexuales de hembras maduras durante el periodo reproductivo de esta especie. Las hembras de O. discoidalis presentan ovarios compuestos por un solo lóbulo, así como folículos ováricos tipo 3 con sectorización citoplasmática debido a la acumulación de plaquetas vitelinas. En algunos de estos folículos, el epitelio es de tipo cuboidal, y la teca está formada por dos capas en los folículos ováricos tipo 3. En cuanto al oviducto, se observa una predominancia de glicoconjugados ácidos con una distribución laberíntica, organizados de manera fibrilar y granular. Este estudio ha permitido identificar características particulares en la arquitectura de los compuestos glucídicos y en el seguimiento de los compuestos oviductales en hembras de O. discoidalis, las cuales serían adecuadas para un modo de puesta fuera del agua.Oreobates discoidalis is an anuran that reproduces in moist and sheltered habitats, laying relatively large eggs directly on land, and undergoing direct development. In this study, we describe the histology of the sexual organs of mature females during the reproductive period. Our observations reveal ovaries consisting of a single lobe, type 3 ovarian follicles exhibiting sectorization of the cytoplasm due to the accumulation of vitelline platelets, with some of these follicles exhibiting cubic epithelium, and theca formed by two layers in type 3 and 4 ovarian follicles. The oviduct is dominated by acid-type glycoconjugates exhibiting a labyrinthine distribution, organized in a fibrillar and granular manner. This study has revealed distinctive features in the architecture of glucid compounds and the monitoring of oviductal compounds in females of O. discoidalis. These characteristics would be suitable for a water-independent mode of reproduction.Fil: Pucci Alcaide, Ana. Universidad Nacional de Tucumán. Facultad de Ciencias Naturales e Instituto Miguel Lillo; ArgentinaFil: Pucci Alcaide, Franco Jose. Fundación Miguel Lillo; ArgentinaFil: Ponssa, María Laura. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico - Tucumán. Unidad Ejecutora Lillo; ArgentinaFil: Michel, Adriana A.. Fundación Miguel Lillo; Argentin
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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