Results 141 to 150 of about 11,636 (194)

The occurrence of diploid ova in Rana pipiens

Journal of Heredity, 1977
All 12 Rana pipiens females tested from three populations produced diploid ova. These were identified by the development of from 0.15 to 35 percent per clutch of normal diploid-like embryos among large numbers of haploid embryos following activation of R. pipiens eggs with irradiated R. clamitans sperm.
C M, Richards, G W, Nace
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The ultimobranchial body in Rana pipiens

Zeitschrift f�r Zellforschung und Mikroskopische Anatomie, 1965
1. Electron micrographs of the ultimobranchial body in sexually mature Rana pipiens were prepared to describe the cytology of the parenchymal cells. 2. Cytoplasmic granules, enclosed within a limiting membrane, are approximately 1000 A in diameter and are found at the apical and basal poles of the nucleus as aggregations and also in the ...
D R, ROBERTSON, A L, BELL
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Plasmacytoma in a Rana pipiens

1969
Though the occurrence of tumors among amphibians has been recognized for many years, these lesions have been considered quite rare. Lucke and Schlumberger (1) reviewed the problem of neoplasia in cold-blooded vertebrates and concluded that amphibians are no less susceptible to neoplasms than other vertebrates.
Sydney S. Schochet, Peter W. Lampert
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Ultrastructure of the jugular body of Rana pipiens

Cell And Tissue Research, 1981
The jugular bodies in adult Rana pipiens, are surrounded by a capsule of mesothelium and connective tissue, and their parenchyma consists of cell cords arranged in a sinusoidal network. The cell cords are formed by irregular reticular cells, showing numerous filaments and joined together by zonulae adherents.
A, Zapata, A, Villena, E L, Cooper
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Transplantation of nuclei between Rana pipiens and Rana sylvatica

Experimental Cell Research, 1958
Abstract 1. 1. New data are offered to show that the cleavage rates of of pip × pip, (pip) × pip, pip × syl, and (pip) × syl embryos are essentially the same. 2. 2. When a diploid Rana sylvatica blastula nucleus is transferred to an enucleated Rana pipiens ovum the resulting embryo develops only to a late blastula stage and then stops. 3.
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The Visual Acuity of the Frog ( Rana pipiens  )

Journal of Comparative Physiology A: Sensory, Neural, and Behavioral Physiology, 1996
The frog's visual acuity for gratings was tested with a two-choice prey-dummy setup. The two dummies had a constant position in the visual field, but in one of them a striped pattern was constantly drifting, while the other was a potentially less attention arousing dummy with non-moving stripes.
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The organizer and respiration in Rana pipiens

Experimental Cell Research, 1951
Abstract It has been found that the respiratory activity of the combined piece of organizer and ectoderm is higher than that of the separated pieces of these two regions, when they are isolated at gastrula stage and measured at neurula stage.
L.G. Barth, L.C. Sze
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Competitive feeding behaviour of Rana pipiens and Rana clamitans

Animal Behaviour, 1971
Abstract Feeding hierarchies based on competition for mealworms were reliably stable over forty-five sessions in three groups of leopard frogs (Rana pipiens) and in three groups of green frogs (Rana clamitans). Green frogs most commonly wrestled during competition and were markedly more vigorous than leopard frogs.
Robert Boice, Richard C. Williams
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Experimental Studies on Hemopoiesis in the Pronephros of Rana pipiens

Differentiation, 1979
Embryogenesis of hemopoietic cell populations in the pronephros of Rana pipiens was examined during embryonic and early larval development. Differential cell counts of Wright-Giemsa-stained cell suspensions demonstrated that granulopoiesis is the predominant hemopoietic activity in the pronephros, erythropoiesis accounts for a minor component of the ...
K L, Carpenter, J B, Turpen
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A study on hearing in frogs (Rana pipiens and Rana clamitans)

Zeitschrift f�r Vergleichende Physiologie, 1959
Die relative Reizschwellkurve fur die Schallempfindung bei den Froschen Rana clamitans und R. pipiens wurde in dem Frequenzbereich von 30–15000 Hz bestimmt. Die Kurve ist dieselbe fur beide Geschlechter. Versuche zeigten, das Schalle entweder inhibierend oder stimulierend auf die Atmungsbewegungen wirken konnen.
Herman Kleerekoper, Kira Sibabin
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