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ABSTRACT
The hypothalamus is a distinct neurological entity concerned with a variety of regulatory processes. Recently, the prescence of variations in the level of neurosecretions wth the progress of age was reported. To study the changes in the structure of magnocellular neurons in the paraventricular and supraoptic nuclei during the period of postnatal development. Furthermore, to study the changes which occurred in the structure of these neurons in the old age had been studied. A total of 52 albino rats were used. The age groups of the animals include one day, 10 days, 20 days, 2 months and 2 years old animals. Brains were processed to be studied with Einarson's gallocyanin-chrome alum stain, Golgi- Cox method and transmission electron microscope. In addition, the number of cells in the magnocellular part of the paraventricular and supraoptic nuclei were measured in all studied age groups and statistically analyzed. In the newly born rats, the paraventricular and supraoptic nuclei were composed of small rounded condensed cells. At the age of 10 days old rats, the paraventricular nucleus appeared to be well differentiated into ventromedial [parvocellular] and dorsolateral [magnocellular] parts. With the progress of age from 10 days up to the adult stage, the cells of the supraoptic nucleus and the magnocellular part of the paraventricular nucleus appeared to be densely stained which indicated increase in the Nissl granules. Ultrastructural study showed that the cells had abundant amount of free ribosomes, rough endoplasmic reticulum and mitochondria. The nucleus had fine dispersed chromatin. Golgi-Cox study showed marked increase in extension and branching of dendrites with the progress of age during the developmental period. Morphometric study showed significant increase in the number of cells from the new born up to the adult stage. In old aged rats, the cells of the paraventricular nucleus and the supraoptic nucleus appeared to be faintly stained. Some cells had vacuolated cytoplasm. Ultrastructural study showed marked decrease in the free ribosomes and the presence of many lipofuscin pigment in the cytoplasm of cells. The nucleus showed chromatin condensation and irregularity of the nuclear membrane. In addition, there was apparent decrease in the amount of the synaptic vesicles in the presynaptic terminals making contacts with the magnocellular neurons. Golgi-Cox study revealed marked decrease in the extension and branching of dentrites. Morphometric analysis showed significant decrease in the number of cells. This study demonstrated in the presence of structural changes in the magnocellular part of the paraventricular nucleus and supraoptic nucleus during the period of development. In old age, the presence of many degenerative changes was observed. This cytoarchitectonic analysis and morphological study could help in the explanation of the functional differences in the various ages
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Index: IMEMR (Eastern Mediterranean) Main subject: Rats / Aging / Hypothalamus, Anterior / Cellular Senescence / Midline Thalamic Nuclei Limits: Animals Language: English Journal: Assiut Med. J. Year: 2014

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Index: IMEMR (Eastern Mediterranean) Main subject: Rats / Aging / Hypothalamus, Anterior / Cellular Senescence / Midline Thalamic Nuclei Limits: Animals Language: English Journal: Assiut Med. J. Year: 2014