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Found: 5 467
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[Effect of exogenous somatotropin on the ultrastructure of somatotropic cells in hyperthyroid rats].
Marked ultrastructural changes indicating a decrease in the cell functional activity occur in the somatotropic cells of rats after chronic hyperthyroidism with 1-thyroxin. Exogenous somatotropin produces no effect on these ultrastructural changes.
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[Morphofunctional features of the secretory cells of the adenohypophysis and adrenal glands of the rat during aging].
Karyometric and electron microscopic investigation has been performed in the adenohypophyseal secretory cells, in the cortex and medulla of the adrenal glands in mature (6 months) and ageing (25-26 months) white male rats. The diameter of the corticotropic cell nuclei of the adenohypophysis significantly increases with age. In the secretory cells of the adrenal cortex and medulla no important changes in their parameters are revealed. With age destructive changes of the ultrastructures are manifested variously in different types of the secretory cells in the endocrinic glands studied. In the corticotropic, somatotropic, thyreotropic cells of the adenohypophysis, in spongiocytes of the adrenal cortex, compensatory ultrastructural rearrangements develop; they are aimed to preserve functional activity of the cells mentioned. No age changes are revealed in ultrastructure of chromaffin cells of the adrenal medulla.
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[Surface structure of nerve tissue transplants growing in the anterior chamber of the rat eye (electron-microscopic study)].
Two different types of the glial envelope are demonstrated around the septal cerebral area grafts (SCAG) and the hippocampal grafts (HG) developing in the anterior eye chamber of the rat during 3-4 months. In the SCAG it is multilayered, consists mainly of modified oligodendrocytes. Processes of the nervous cells perforate the surface of the envelope. In the HG the unilayered glial envelope consists of bodies and processes of the fibrous astrocytes; it is impenetrable for the nervous processes. Since both types of the cellular elements making these envelopes have been described in the norm, it is possible that the differences in the surfaces described are specific for these structures.
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Ultrastructural alterations in the initial segments and in the recurrent collateral terminals of Purkinje cells following axotomy.
Transection of Purkinje cell axons in adult male rats made 1.5 mm or further from the cell body does not lead to the death of the neuron and results in compensatory structural alterations of the surviving axonal portions of the nerve cell. Near to, and at the emergence of recurrent collaterals of Purkinje cell axons, huge varicosities filled with filaments, granular material, lysosomes and mitochondria develop. Terminals of recurrent axon collaterals also exhibit different degrees of structural changes. Most striking of the morphological alterations is the regular presence of nematosomes in the hypertrophic axonal branches, especially in synaptic terminals. Since nematosomes were shown to contain RNA in other types of neurons, their presence in recurrent collaterals may indicate an enhanced synthetic activity in Purkinje axonal processes and endings after axotomy.
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Ultrastructural study of the human neurohypophysis. III. Vascular and perivascular structures.
The vascular and perivascular regions of the human neurohypophysis were studied electron microscopically. The abluminal basement membrane, perivascular space, luminal basement membrane and endothelium are interposed between the neural parenchyma and the blood stream. The capillaries are fenestrated, with pores measuring 30 to 50 nm in diameter. The perivascular and intercellular spaces form prominent networks that penetrate between rows of neurohypophysial parenchymal cells. The perivascular space contains pericytes, histiocytes, fibroblasts and mast cells, with ultrastructural features typical of each cell type. No transitional forms between histiocytes and pericytes were observed. A schema for the extracellular flow of neurohypophysial hormones through the sinusoidal and perivascular spaces is proposed, suggesting an important role for the pituicytes and their intercellular junctions in the control of hormone release.
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[Secretory phenomena at the ependyma of the sulcus hypothalamicus Monroi of the fetal rat. A histochemical and electron microscopic study].
In a localized area above the sulcus hypothalamicus Monroi ventriculi tertii of the rat ependymal structures are observed, which only occur between the 18th and 20th day of gestation. They were investigated with the aid of lightmicroscopic, ultrastructural and histochemical technics. The surface of the ventricular wall is rendered irregular by protrusions and deposits. Neurosecretory stains and histochemical examination give no positive results. Apical parts of the ependymal cells are fingershaped, dome-like and of spheric appearance. The equipment of the protrusions with organels is variable. Some of them contain a fine granular ground plasma, polyribosomes and occasional profiles of the endoplasmatic reticulum. Others are impacted with optic empty or substantial vacuols. Vacuols merging in the cellular membrane evacuate their content into the ventricular space. Multivesicular bodys engorged with vesicles are together with those, which lie empty in the ventricular cavity. Empty, buddle like and frequently folded membrane protrusions suggest that cellular content has been delivered into the ventricle.
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The pineal gland of the mole (Talpa europaea L.). II. Ultrastructural variations observed in the pinealocytes during different parts of the sexual cycle.
Changes of some ultrastructural parameters (paracrystalline structures, Golgi apparatus, secretory granules) in mole pinealocytes were quantitatively studied during the various phases of the sexual cycle. An increase in quantity of paracrystalline structures and of the Golgi appratuses was demonstrated during the period of high sexual activity in male pinealocytes and during oestrus, gestation and lactation in female pinealocytes. Moreover, the appearance of vacuoles in female pinealocytes was observed during pro-oestrus. These results seemto demonstrate close relationship between the endocrine activity of the hypophyseo-gonadal axis and the synthesis of some compounds by the pinealocytes. No increase in the quantity of secretory granules was observed during the various phases of the sexual cycle studied. Key words: pinealocytes, mole, sexual cycle, ultrastructure, paracrystalline structure.
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The commissural neurons of the inferior colliculus of the rat.
During systematic observation of the cellular subnuclei of the inferior colliculus of adult rats, it was noted that in the zone of the intercollicular commissure, numerous neuronal perikaria appear intermingled between the commissural fibers. The neurons were studied using Golgi and TEM methods and classified according to their dendritic pattern in the isodendritic (15%), allodendritic (19%) and intermediate forms (66%) of neurons. A fourth neuronal group, situated between the commissure and the upper periventricular zone, is also in relation with the commissural fibers. The constancy of these neurons and their frequently axodendritic and axosomatic synapses suggest that they play an important role in the whole function of the commissure which, at present, is not well understood in spite of the number and distinct origin of their afferents.
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[Morphofunctional characteristics of the associative region of the cerebral cortex in experimental neuroses in the dog].
Ultrastructure of neurones and synapses of the cortical associative area of dogs has been studied under conditions of experimental neuroses caused by prolonged informational loads with constant time deficit and high motivational signals significance. Analysis of subcellular reorganization of a number of neuronal and synaptic organelles showed the degenerative changes of afferent conducting systems in various neuropil parts leading to the falling out of definite neuronal groups from stable functional connections and to the disturbance of intracortical interrelations. In the cortex simultaneously with destructive processes, are developing intracellular compensatory-adaptive reactions.
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Asymmetry of the habenulae in the elasmobranch "Scyllium stellare". II. Electron microscopy.
The structure of the habenular nuclei of the elasmobranch Scyllium stellare has been examined with the electron microscope. There is asymmetry of the left and right habenulae; difference is manifest in their cell types and myelin distribution. The presence in only the left habenula of cells bearing large granules - probably secretory - and of cells with myelinated perikarya suggest a functional diversification of the habenulae. A large variety of synaptic vesicles occur in the habenulae of both sides but we could not demonstrate a preferential localization of one particular type in specific habenular subnuclei. A feature common to all portions of the habenular complex is the presence of multilamellar astroglial formations wrapping cell bodies and synapses.