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Comparative Aspects (comparative + aspect)
Selected AbstractsTwo-dimensional psychophysics in chickens and humans: Comparative aspects of perceptual relativityJAPANESE PSYCHOLOGICAL RESEARCH, Issue 4 2008PETRA HAUF Abstract:, Whereas the contextual basis of psychophysical responding is well founded, the compound influence of sensory and perceptual frames of reference constitutes a challenging issue in comparative one- and multidimensional psychophysics (e.g., Sarris, 2004, 2006). We refer to previous investigations, which tested the assumption that the chicken's relational choice in the one-dimensional case is systematically altered by context conditions similar to the findings stemming from human participants. In this paper mainly the context-dependent stimulus coding was investigated for the important, but largely neglected, two-dimensional case in humans and chickens. Three strategies were predicted for the generalization of size discriminations, which had been learned in a different color context. In two experiments, which varied in the testing procedure, both species demonstrated profound contextual effects in psychophysics; they differed, however, in the way the information from either dimension was used: Chickens throughout used color as a cue to separate the respective size discriminations and generalizations. Whereas humans predominantly generalized according to size information only or according to absolute stimulus properties, the chickens showed some important species-specific differences. Common and heterogeneous findings of this line of comparative research in multidimensional psychophysics are presented and discussed in various ways. [source] Comparative aspects of the inner root sheath in adult and developing hairs of mammals in relation to the evolution of hairsJOURNAL OF ANATOMY, Issue 3 2004Lorenzo AlibardiArticle first published online: 17 SEP 200 Abstract The inner root sheath (IRS) allows the exit of hairs through the epidermal surface. The fine structure of monotreme and marsupial IRS and trichohyalin is not known. Using electron microscopy and immunocytochemistry, the localization of trichohyalin and transglutaminase have been studied in monotreme and marsupial hairs, and compared with trichohyalin localization in placental hairs. Trichohyalin in all mammalian species studied here is recognized by a polyclonal antibody against sheep trichohyalin. This generalized immunoreactivity suggests that common epitopes are present in trichohyalin across mammals. In differentiating IRS cells, trichohyalin granules of variable dimensions are composed of an immunolabelled amorphous matrix associated with a network of 10,12-nm-thick keratin filaments. Transglutaminase labelling is present among keratin bundles and trichohyalin granules, and in condensed nuclei of terminally differentiating cells of the inner root sheath. The IRS in monotreme hairs is multistratified but lacks a distinguishable Henle layer. Cornification of IRS determines the sculpturing of the fibre cuticle and later shedding from the follicle for the exit of the hair fibre on the epidermal surface. It is hypothesized that the stratification of IRS in Henle, Huxley and IRS cuticle layers is derived from a simpler organization, like that present in the IRS of monotremes. The IRS is regarded as a localized shedding/sloughing layer needed for the exit of hairs without injury to the epidermis. The formation of the IRS during the evolution of mammalian epidermis allowed the physiological exit of hairs produced inside the skin. The peculiar morphogenesis of hairs in possible primitive skins, such as those of the monotremes (mammals with some reptilian characteristics) or the tails of some rodents (a scaled skin), may elucidate the evolution of hairs. In monotreme and rodent tail skin, the dermal papilla remains localized on the proximal side of the hair peg and forms a hair placode with bilateral symmetry. The papilla is progressively surrounded by the down-growing hair peg until a dermal papilla with radial symmetry is formed. It is speculated that the progressive reduction of the extended dermal papilla of reptilian scales into small and deep papillae of therapsid reptiles produced hairs in mammals. [source] The Spleen of Zaedyus pichiy, (Mammalia, Dasypodidae): a Light and Electron Microscopic StudyANATOMIA, HISTOLOGIA, EMBRYOLOGIA, Issue 4 2003E. J. Galíndez Summary Armadillos are ancient mammals important as models for biomedical, evolutive and ecological studies, because they have adaptive and primitive morpho-physiological characteristics. In this work we study the splenic microarchitecture of the ,Patagonian Piche', Zaedyus pichiy, as an attempt to understand the relationship between the organizational plan of the organ and the particular features of this species. The organ samples were classically processed for light and electron microscopic study. The microanatomy of the organ as well as its different cell types are studied. The spleen is non-sinusoidal, with the typical arrangement for storage functions. White pulp is well defined. Red pulp is a meshwork of circulating, immunocompetent and haemopoietic cells. The general structure of the organ agrees with the semi-fossorial habit and the adaptability of the species. Comparative aspects with other armadillos or other less specialized groups are discussed. Persistence of haemopoietic spleen activity in the adult suggests the existence of specific inductive functions of the stroma. Better knowledge of spleen structure and function in ancient mammals may give important information about their phylogeny. [source] Canine neoplasia , Introductory paperAPMIS, Issue 2008HANS GAMLEM The paper gives a brief introduction to canine oncology, including its comparative aspects as basis for recording tumours in the animal kingdom. In an abbreviated presentation of the Norwegian Canine Cancer Project for the years 1990 , 1998, the data (n=14,401) were divided into age groups, each of two years, into different categories of tumours, and into age and gender. As expected, cutaneous histiocytoma was the dominant tumour type in both sexes during the two first years of life. In the age group 2 , 3.99 years histiocytoma was still the largest group in males, but was surpassed by benign epithelial skin tumours in females. After the age of 4 years, benign epithelial skin tumours constituted the greatest circumscribed group in males, and mammary tumours in females, although the summated other tumours, not explained in this survey, dominated overall in males. Maligancies (cancer) were shown in the same way, by corresponding groups of gender and age. While mastocytoma was the most common tumour and non-Hodgkin's lymphoma the second most common during the two first years of life in females, the situation was reversed in males. Later, mammary tumours dominated in females, while different tumour types not further specified in this summarized report dominated in males, until the end of the age registration (above 14 years). Number, sex and location of most common tumours are shown in a tabular outline. Comparative aspects between human and dog tumours are considered: mammary and testicular neoplasia seemed more frequent in dogs than in humans in Norway, while intestinal, pulmonary and prostatic malignancies were less common in dogs. In our study, vascular tumours and tumour-like lesions constituted about 3% of the total data. As benign vascular tumours are incompletely reported to the human Cancer Registry, no dependable comparison may be made, but malignant vascular tumours have been on the rise during the last decades in the Norwegian human population, more so in men then in women. Finally, the article deals briefly with the development of endothelial cells, and the sparse information on causal factors of vascular tumours. [source] Erythropoiesis and red cell function in vertebrate embryosEUROPEAN JOURNAL OF CLINICAL INVESTIGATION, Issue 2005R. Baumann Abstract All vertebrate embryos produce a specific erythroid cell population , primitive erythrocytes , early in development. These cells are characterized by expression of the specific embryonic haemoglobins. Many aspects of primitive erythropoiesis and the physiological function of primitive red cells are still enigmatic. Nevertheless, recent years have seen intensive efforts to characterize in greater detail the molecular events underlying the initiation of erythropoiesis in vertebrate embryos. Several key genes have been identified that are necessary for primitive and the subsequent definitive erythropoiesis, which differs in several aspect from primitive erythropoiesis. This review gives in its first part a short overview dealing with comparative aspects of primitive and early definitive erythropoiesis in higher and lower vertebrates and in the second part we discuss the physiological function of primitive red cells based mainly on results from mammalian and avian embryos. [source] Canine neoplasia , Introductory paperAPMIS, Issue 2008HANS GAMLEM The paper gives a brief introduction to canine oncology, including its comparative aspects as basis for recording tumours in the animal kingdom. In an abbreviated presentation of the Norwegian Canine Cancer Project for the years 1990 , 1998, the data (n=14,401) were divided into age groups, each of two years, into different categories of tumours, and into age and gender. As expected, cutaneous histiocytoma was the dominant tumour type in both sexes during the two first years of life. In the age group 2 , 3.99 years histiocytoma was still the largest group in males, but was surpassed by benign epithelial skin tumours in females. After the age of 4 years, benign epithelial skin tumours constituted the greatest circumscribed group in males, and mammary tumours in females, although the summated other tumours, not explained in this survey, dominated overall in males. Maligancies (cancer) were shown in the same way, by corresponding groups of gender and age. While mastocytoma was the most common tumour and non-Hodgkin's lymphoma the second most common during the two first years of life in females, the situation was reversed in males. Later, mammary tumours dominated in females, while different tumour types not further specified in this summarized report dominated in males, until the end of the age registration (above 14 years). Number, sex and location of most common tumours are shown in a tabular outline. Comparative aspects between human and dog tumours are considered: mammary and testicular neoplasia seemed more frequent in dogs than in humans in Norway, while intestinal, pulmonary and prostatic malignancies were less common in dogs. In our study, vascular tumours and tumour-like lesions constituted about 3% of the total data. As benign vascular tumours are incompletely reported to the human Cancer Registry, no dependable comparison may be made, but malignant vascular tumours have been on the rise during the last decades in the Norwegian human population, more so in men then in women. Finally, the article deals briefly with the development of endothelial cells, and the sparse information on causal factors of vascular tumours. [source] | |||||||||||||