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The aim the study was to discover the structure and topography of formatio hippocampi in chinchillas (Chinchilla brevicaudata). Investigations were carried out on the brains of 5 chinchillas. The material was preserved in buffered 10% formalin, and then dehydrated in ethyl alcohol of rising concentrations, embedded in paraffin blocks and cut transversally into 12 micrometer-thick sections. The sections were then stained according to Klüver and Barreras method. The formatio hippocampi, classified as a part of the rhinencephalon, are located in the medial part of the cerebral hemisphere, and indents in an arch into the light of the lateral ventricle. In the case of chinchillas the fomatio hippocampus consists of the hippocampus and dentate areas and the following cortical nervous structure: subiculum and four areas from CA1 to CA4. Formatio hippocampi as a cortical structure has a laminar build. The following layers may be distinguished in the subiculum: the marginal layer and cellular layer I and II. The structure of CA1, CA2, CA3, CA4 areas contains the following layers: stratum oriens, stratum pyramidal, stratum radiatum, and stratum molecular. The dentate area is a part of the formatio hippocampi formed by the gyrus dentatus and hilus fasciae dentate. Gyrus dentatus as a cortical structure has a laminar build. It is made up of two layers: molecular stratum and granular stratum.
The main aim of the study was to investigate the intracellular localization of the following calcium-binding proteins: parvalbumin, calbindin and calretinin. 15 sexually mature chinchilla males (about 1.5 years old) were used in the examination. The hippocampus was collected from each immediately after the slaughter, fixed and properly prepared for immunohistochemical examinations. Peroxidase-anti-peroxidase (PAP) reaction was carried out using specific antibodies against parvalbumin and calbindin D28k, as well as calretinin. Our own examination results have shown cytoplasmic as well as nuclear reactions in the examined regions of the hippocampal areas (CA1-CA4) and dentate gyrus. Only in the CA2 area was no nuclear reaction observed for the examined proteins, as well as in the CA1 area for calretinin. Intracellular localization of calcium-binding proteins proves that regulatory functions of parvalbumin, calbindin and calretinin lead to neuronal plasticity, i.e. to a change of their activity. Therefore, calcium-binding proteins may be indirectly involved in the regulation of metabolic processes affecting basic vital functions of neurons.
The aim of the study was a quantitative and cytoarchitectonic examination of neurons of the ventral hippocampal CA1-CA4 fields in somatically mature female American mink (Neovison vison) (N = 6). Brains were removed and examined under a light microscope. The samples were stained by Nissl’s standard method, and histological samples were used for morphometric analysis. All ventral hippocampal CA1-CA4 fields were analyzed cytoarchitectonically and morphometrically with a calibrated image analysis system that consisted of a computer equipped with the Cell^D software Soft Imaging System (SIS) with an integrated digital camera Colorview IIIu (Soft Imaging System). Morphometric investigations of the pyramidal layer showed that the cells of the hippocampal CA1-CA4 fields in adult female American mink differ in size, shape, cell area, nucleus area and the nucleus-to-cell ratio (in%). The cells of the CA2 field were densely arranged, pyramidal and contained a small amount of cytoplasm; their size was differentiated. They were the largest in size (15.06 μm) and diameter (14.5 μm). The cells of the CA1 field had the smallest size (8.5 μm) and diameter (8.6 μm). In the CA3 field, small, densely packed neurons dominated, whereas neurons in the CA4 field formed a thin strand of loosely arranged cells. Given the increasing interest in hippocampal areas, it is necessary to continue studies of their morphology and morphometry in healthy animals and in those suffering from neurodegenerative diseases.
The aim of the study was a morphometric analysis of the ventral hippocampal neurons of the individual CA1-CA4 fields in domestic cattle (Bos taurus; N = 6). The hippocampus in cattle is formed by a sizable arched invagination of the medial wall of the lateral ventricle of the brain. The brains were removed and analyzed conventionally with a light microscope. The samples were stained by Nissl’s method. The morphometric analysis of the neurons of the hippocampal CA1-CA4 fields included the following parameters: the area of nervous cells and the area of the cell nucleus in μm²; the nucleus-to-cell ratio in %; the average diameter and perimeter of the nervous cell in μm. The morphometric investigations indicate that the cells of the pyramidal layer in the CA1-CA4 fields of the hippocampus in adult domestic cattle differ in terms of their size, shape, and surface area, as well as the surface area of the cell nucleus. The size of cells in CA1 was the largest, fluctuating around 22 μm, whereas in CA4 it amounted to about 19 μm. Cells in CA1 and CA2 had the largest diameter of about 24 µm, whereas cells in the CA4 field had the smallest diameter of about 20 µm. The results obtained suggest a novel approach to studying the morphometric properties of the hippocampus in domestic cattle. Morphometric studies of the central nervous system (CNS) are regarded as a valuable source of data on the function of environmental and pharmacological factors and their effects on several structures of the CNS.
The aim of the study was to investigate acetylcholinesterase-immunoreactive neurons in the CA1 area of the hippocampus and in the striatum (CS) of rats receiving rebaudioside A (RebA) for 15 days. RebA is a steviol glycoside used in the production of sweeteners, and it has been shown that glycosides affect memory and learning processes. RebA was administrated to adult rats for 15 days at 1 mg of glycoside/ml of water (group I) and 2 mg of glycoside/ml of water (group II). An indirect immunohistochemical peroxidase-antiperoxidase reaction was performed on frontal slides containing the hippocampus and CS with the use of a monoclonal antibody against AChE. Neurons immunoreactive for the protein were assessed morphologically and morphometrically in hippocampal area CA1 and in the CS. Microscopical observations did not reveal significant morphological changes in immunopositive neurons, which suggests that the glycoside had no neurotoxic effect of these cells. Morphometric analyses did not show changes in the density of AChE-immunoreactive neurons. On the other hand, a decrease in reaction intensity was demonstrated in hippocampal area CA1 in group I and in the CS in both groups of animals receiving RebA. The results of our preliminary studies suggest that RebA affects cholinergic neurons.
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