Results 141 to 150 of about 1,233 (179)
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Occipital spine ofOrthacanthus (Xenacanthidae, Elasmobranchii): Structure and growth
Journal of Morphology, 1999The morphology of 16 occipital spines of the xenacanthid Orthacanthus from Upper Carboniferous deposits of Robinson (Kansas, USA), Nýran (Czech Republic) and Puertollano (Spain) is described. The nonreplaced spines reveal the growth pattern of the shark.
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Dentition of the apron ray
The present study provides quantitative and qualitative analyses of the dentition of Discopyge tschudii. Overall, 193 individuals (99 males and 94 females) of D. tschudii were collected on scientific trawl surveys conducted by the National Institute for Fisheries Research and Development (INIDEP) and commercial vessels in Argentina.
Spath, María Cecilia +2 more
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Bycatch of Demersal Elasmobranchii in the Strait of Sicily
Journal of Coastal ResearchFishing activities greatly threaten Elasmobranchii due to their vulnerable life-history traits. Elasmobranchii have been a common bycatch in the Mediterranean bottom trawling fleets since the 1970s, and most of them are listed as threatened owing to overexploitation by fisheries.
Falsone, F. +9 more
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Morphological Indicators of Olfactory Capability in Wobbegong Sharks (Orectolobidae, Elasmobranchii)
Brain, Behavior and Evolution, 2009Elasmobranchs are thought to possess an acute sense of smell, but the relationship between the anatomy of their olfactory organs and their sensory ecology is poorly understood. Moreover, the ecological diversity of elasmobranchs as a group indicates that there might be considerable interspecific variation in the importance of the olfactory sense ...
Theiss, S. M. +2 more
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THE RETENTION AND PHYSIOLOGICAL ROLE OF UREA IN THE ELASMOBRANCHII
Biological Reviews, 1936Summary.The high urea content (2·0 and 2·5 per cent.) that characterises the blood, body fluids and tissues of the Elasmobranchii owes its origin to the relative impermeability of the gills and integument to this substance, and to the circumstance that the urea is actively conserved by the elasmobranch kidney.In consequence of this physiological ...
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The cardiac ultrastructure of Chimaera monstrosa L. (Elasmobranchii: Holocephali)
Cell and Tissue Research, 1979The ultrastructure of the heart in Chimaera monstrosa L. is described. The endocardial and the epicardial cells are similar in the three cardiac regions. Myocardial cells show small variations. The myofibred, 4--6 microns thick, contains one or a few myofibrils. Each myosin filament is surrounded by six actin filaments.
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Comparative Biochemistry and Physiology, 1966
Abstract 1. 1. Carbamoyl phosphate synthetase activity has been demonstrated in sucrose homogenates of elasmobranch livers. Some properties of the enzyme are reported. 2. 2. Ammonia and glutamine act equally well as substrates except for Raia circularis liver which uses only glutamine. 3. 3. Enzyme activity is stimulated by pretreatment
D C, Watts, R L, Watts
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Abstract 1. 1. Carbamoyl phosphate synthetase activity has been demonstrated in sucrose homogenates of elasmobranch livers. Some properties of the enzyme are reported. 2. 2. Ammonia and glutamine act equally well as substrates except for Raia circularis liver which uses only glutamine. 3. 3. Enzyme activity is stimulated by pretreatment
D C, Watts, R L, Watts
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Polymorphism of the surface sculpture of placoid scales of sharks (Selachomorpha, Elasmobranchii)
Doklady Biological Sciences, 2012adult individual of each species: Chiloscyllium punc tatum (Hemiscyllidae, Orectolobiformes), Carcharhi nus plumbeus, Carcharhinus sorrah (Carcharhinidae, Carcharhiniformes), Apristurus profundorum, Penta chus spp. (Scyliorhinidae, Carcharhiniformes), Gale orhinus galeo (Triakidae, Carcharhiniformes), Squalus fernandinus, Scymnodon obscurus ...
O F, Chernova, E I, Vorob'eva
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Ultrastructure of the pituitary complex in the genus Raia (elasmobranchii)
Zeitschrift f�r Zellforschung und mikroskopische Anatomie, 1972A single secretory cell type is predominant in the neurointermediate lobes of Raia clavata, R. batis and R. radiata; a few glia cells are also present. Nerve bundles entering the lobe between the cell cords contain two secretory nerve types, and possibly a third type devoid of secretory granules. Type A axons containing granules of mean diameter 2000 A
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Morphogenesis and histology of large scales of batoids (Elasmobranchii)
Paläontologische Zeitschrift, 1979Large scales occur only in three families of batoids. Though they have a wide spectrum of different shapes they all serve protective functions in bottom-dwelling species. The crown consists of enameloid, orthodentine and osteodentine. Three different types of basal plates occur: (a) thin basal plate consisting of acellular bone; (b) basal plate which ...
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