Effect of chronic stress on the ultrastructure of the myocardium and hypothalamus of "emotional" and "nonemotional" rats

The influence of chronic stress on the ultrastructure of the myocardium and hypothalamus was studied in experiments on male rats with different levels of emotional-behavioral reactivity. "Emotional" rats manifested a pronounced increase in glycogen granules in myocytes and intercellular space, appearance of the areas of overcontraction of myofibrils, conglomerates of aggregated platelets in myocardial capillaries, and red cell egress from myocardial and hypothalamic capillaries. Alterations in the ultrastructure of the myocardium and hypothalamus in "nonemotional" rats were less marked and consisted in the appearance of the areas of overcontraction of myofibrils, enlargement of sarcoplasmic reticulum caverns, and in an increase in the lipid content in cardiomyocytes. The ultrastructural changes in the myocardium and hypothalamus of "emotional" and "nonemotional" rats indicate different reactivity of the animals and are likely to be accounted for by different levels of activation of their adrenergic systems.     

The ultrastructural basis of transcapillary exchanges

A brief survey is given of current views correlating the ultrastructural and permeability characteristics of capillaries. Observations based on the use of peroxidase (mol wt 40,000), as an in vivo, and colloidal lanthanum, as an in vitro, ultrastructural tracer, are presented. In capillaries with "continuous" endothelium, the endothelial intercellular junctions are thought to be permeable to the tracers, and are regarded as maculae occludentes rather than zonulae occludentes, with a gap of about 40 A in width between the maculae. Some evidence for vesicular transport is also presented. It is inferred that the cell junctions are the morphological equivalent of the small-pore system, and the vesicles the equivalent of the large-pore system. Peroxidase does not apparently cross brain capillaries: the endothelial cell junctions are regarded as zonulae occludentes, and vesicles do not appear to transport across the endothelium. This is regarded as the morphological equivalent of the blood-brain barrier for relatively large molecules. The tracers appear to permeate the fenestrae of fenestrated capillaries, and the high permeability of these capillaries to large molecules is attributed to the fenestrae. Capillaries with discontinuous endothelium readily allow passage of the tracers through the intercellular gaps. A continuous basement membrane may act as a relatively coarse filter for large molecules. In general, the morphology of capillaries correlates well with physiological observations.     

The postnatal development of capillaries in the triceps muscle of arm of the white rat. Light and electron microscopic studies]

This paper continues former ultrastructural investigations about fetal development of capillaries in the muscle anlage of the fore limb of white rats. Present investigations deal with postnatal ultrastructural changes of the capillaries of the triceps muscle of rats from the 4th up to the 23rd day p.p. Counting of the capillaries with light and electron microscope reveal a linear increase of the capillary to fiber ratio in this period proportional to the growth of the muscle. Related to a defined area however the number of capillaries remains constantly. Ultrastructural changes of capillaries consist in further flattening of the endothelial profiles, decrease in number or organelles (mitochondria and endoplasmic reticulum), while the number of pinocytotic vesicles remains highmthe endothelial joints become less interdigitated, the basement membrane shows an increase in density leading to a temporary decrease in thickness. Since the 9th postnatal day all of the capillaries including buds closely border upon the muscle fibres. The distance between endothelium and myofiber diminishes up to 0,1 mum.     

Ultrastructural changes in cardiomyocytes and heart muscle capillaries after vagotomy and physical exertion

Electron microscopic studies of the changes in cardiomyocytes and capillaries of the cardiac muscle were performed in white mice after partial extracardiac parasympathectomy and graded physical exercise. It has been established that submaximum physical exercise leads to slight ultrastructural alterations in the left ventricular cardiomyocytes and capillaries. Maximum physical exercise in intact animals is followed by still greater ultrastructural changes in the heart muscle. Swelling of mitochondria with the focal destruction of crysts, widening of sarcoplasmic reticular cisterns, disturbance of sarcomer to mitochondrion ratio, endotheliocyte edema and narrowing of the capillary lumen are observed. In vagotomized animals fulfilling running exercises of submaximum load dystrophic changes in cardiomyocytes and capillaries are noted only at early stages (day 7). Maximum physical exercise in animals with disturbed integrated nerve influences promotes the development of focal destructive changes in the myocardium.     

Ultrastructure of sensorimotor cortex neurons in the progeny of rats receiving alcohol during pregnancy

Dynamics of ultrastructural changes in the sensomotor cortex neurons has been studied on the 21st, 30th and 60th days of life in offspring born by the rats given 20% alcohol (2 g/kg) during pregnancy. Moderate antenatal alcoholization produces certain disturbances in the ultrastructure of the cortical neurons and their dendrites. This is manifested as presence of retardation signs in maturation of nervous cell populations, as dystrophic changes in the neurons and their dendrites and display of reparative character with their own dynamics in the postnatal period of ontogenesis. The first two categories of the ultrastructural changes in the cortical neurons are more manifested at early stages of the postnatal development of the offspring, and the reparative processes--at the age of two months. Despite the presence of the reparative shifts, the dystrophic changes of the neurons of hypoxic character are present up to the period of sexual maturation. This demonstrates that the antenatal alcoholic intoxication in the offspring is manifested in the postnatal ontogenesis for a long time.     

Early ultrastructural reactions in various parts of the visual analyzer in guinea pigs after thermogenic microwave irradiation]

A single total radiation of guinea pigs by means of microwaves of thermogenic intensity (energy density stream 60 mVt/sm2) and exposition for 10 min produces ultrastructural reactions in various parts of the visual analyser, differing in their manifestation degree. The most essential alterative changes have been revealed in the retina, appearing in 6 h after radiation, as degeneration of the membrane disks of the photoreceptors and as enhancement of phagocytic activity of pigmentocytes, and immediately after the radiation--as destructive disturbances of mitochondria in radial glyocytes and as reaction of the synaptic apparatus. In the cerebral visual centers a higher reactivity of neurons of the external geniculate bodies than in the visual cortex is noted, but ultrastructural disturbances of the hematoencephalic barrier and synapses of the visual cortex are more manifested. Early ultrastructural changes in the optic nerve are least manifested.     

Ultrastructure of epithelial cells in rat's epididymal caput in experimental hyperprolactinemia induced by metoclopramide

The aim of the performed studies has been to find out wether or not the ultrastructural alterations of the epithelial cells in the rat's epididymal caput occur in hyperprolactinemia induced by metoclopramide and to see if the observed changes are of reversible character. It has been revealed that prolactin concentration was twice as high as in control animals due to peritoneal administration of metoclopramide in a dose of 2.2 mg/kg body mass, given for 14 days. The ultrastructural alterations in the principal cells of epididymal caput affected cellular organelles being involved in proteins synthesis, glycosylation, secretion as well as energetic processes. They were manifested by decreased amount of rough endoplasmic reticulum, widening of its cisternae combined with degranulation, distension of Golgi apparatus cisternae, elevated number of vesicles in apical part of the cells, and changes in mitochondria. The termination of metoclopramide administration made prolactin concentration exhibit values being almost similar to those determined in control rats, whereas the ultrastructural changes in the principal cells were found to be reversible.     

Effect of gamma-radiation of an extremely high dose on the cerebral cortex of the rat (ultrastructural aspects)

For 24 h after total gamma-radiation of mature Wistar male rats (180-210 g) in the dose of 150 Gy, ultrastructural rearrangements of the cerebral sensomotor cortex are presented as small destructive changes in neurons, neuroglia and vascular endothelium. Total combination of the changes in ultrastructure of the blood capillaries and perivascular astrocytes makes it possible to suppose that permeability of the microvascular bed wall is increased. At this period, together with the destructive changes there are evidently certain compensatory-restorative processes, developing in the cerebral tissue. It is possible to suppose that already during the first hours after the radiation the ultrastructural changes of neurons are resulted not only from the direct effect of radiation, but from certain influences of the radiation damage of neuroglia and microvessels.     

Prenatal moderate effects of alcohol on ultrastructure of cortical capillaries in the offspring]

Sensorimotor cortex of rat 21- and 30-day-old offspring given prenatally moderate alcohol doses revealed signs of hemodynamic, ultrastructural capillary and compensatory-adaptive changes. The 60-day-old offspring displayed the tendency to hemodynamic and ultrastructural reversibility in remaining edema of the pericapillary processes of astrocytes. It is suggested that the deficiency of cerebral circulation is a delayed aftereffect of prenatal brain hypoxia. Under alcohol intoxication before pregnancy the edema was not observed. There was polymorphism of ultrastructure of cortical capillaries and immature vessels in the offspring.     

Microcirculatory bed of serous membranes in rats with spontaneous genetic hypertension]

The microvasculature (MV) of serous membranes was compared in rats with spontaneous genetic hypertension (SHR) and in normotensive Wistar rats. The study showed that in hypertension MV lesions had a systemic distribution, as structural changes were present in every MV component (arterioles, precapillaries, capillaries, postcapillaries, venules, lymphatic capillaries, and postcapillaries, nerve fibers); these lesions were generalized, as similar alterations could be found in all serous membranes studied. A close resemblance observed between MV of serous membranes in SHR and in patients who died of hypertensive disease confirms the concept suggesting the existence of MV changes which were relatively specific for hypertension, along with those of the nonspecific nature. Specificity of the hypertensive process is manifested in severe vascular lesions of a peculiar type, while the nonspecific phenomena are represented by a combination of intravascular, perivascular, and minimal vascular alterations represented by a universal MV response to various stresses.     

Ultrastructural changes in Shigella flexneri cells during interaction with bacteriocinogenic Lactobacillus acidophilus

Results of electron-microscopic examination of Shigella flexneri cells, subjected to influence the bacteriocin-producing Lactobacillus acidophilus bacteria are presented. The response of shigellae to bacteriocinogenic lactobacilli was shown both on cellular and population levels. On population level the correlation of various morphological types of shigella cells with increase of involution, lysing and resting forms is revealed. At a cellular level the specific ultrastructural changes of shigella evidencing the significant destructive processes of the cells were revealed. In one case destabilization of shigella cellular wall was observed, that was manifested in expansion of periplasmic spaces and appearence of specific involution forms of the cells. In other cases, changes in the ultrastructural organization of shigella nucleoid were found out, manifested in disappearance of thin-fibrillar DNA and formation of electronic-dense globular structures of the cells.     

Ultrastructure of the tegmentum vasculosum of the chicken cochlea

Ultrastructural studies have been made on the dark and light cells, as well as on their interconnections with capillaries in the tegmentum vasculosum of the chick cochlea. The dark cells exhibit ultrastructural peculiarities which are typical for ion transporting cells: their lower part is presented by a system of numerous cytoplasmic projections filled with mitochondria. The role of the light cells is less evident. It is suggested that they may control the exchange of ions and other metabolites between the dark cells and capillaries. Significant ultrastructural differences are described between the tegmentum vasculosum in chicks and the stria vascularis in mammals.     

Ultrastructural studies of muscle cells and vascular endothelium immediately after freeze-thaw injury

Little is known about the ultrastructural changes which occur in vascular endothelium immediately after an in vivo freezethaw insult, although most investigators will agree that tissue viability relates directly to the degree of vascular damage. In this study an electron microscopic examination of an in vivo model for frostbite injury was initiated. The horseradish peroxidase technique was utilized to follow early alterations in capillary flow and the independent effects of hypoxia, cooling to 2 °C, supercooling, and a single freeze-thaw insult were assessed. No precipitous changes in muscle cell mitochondria or capillary endothelium were detected as a result of brief hypoxia, cooling at 2 °C, or supercooling to ?13 °C. Reducing the temperature by 1 °C/min until freezing occurred, continuing to cool for 10 min postheat of fusion, and rapidly rewarming resulted in consistent mitochondrial damage in muscle cells and marked degeneration of associated capillaries. Peroxidase injected iv prior to thawing was rarely localized in the capillaries of previously frozen muscle. Since peroxidase was found in the capillaries of unfrozen legs of the same animals, it is inferred that little or no flow occurred in most capillaries postthaw. Ultrastructural integrity of capillaries immediately after thawing may be a good index for predicting tissue loss.“In conducting the research described in this report, the investigators adhered to the ‘Guide for Laboratory Animal Facilities and Care,’ as promulgated by the Committee on the Guide for Laboratory Animal Facilities and Care of the Institute of Laboratory Animal Resources, National Academy of Sciences-National Research Council.”     

Adaptive ultrastructural changes in soil-resident Yersinia pseudotuberculosis bacteria

After the prolonged residence (from 1 month to 2 years) in flow soil columns at 6 - 8 degrees C and 18 - 20 degrees C a complex of ultrastructural changes was detected in Y. pseudotuberculosis bacteria, depending on temperature, the duration of residence in the soil and, to a definite extent, on the strain. They were manifested in the form of cell-wall changes, the formation of the capsule and intercellular slime, changes in the ribosomal saturation of cytoplasm and the conformation state of DNA in the nucleoid zone. As the result of adaptation to nutritional deficit storage substances were accumulated in the form of electron-dense inclusions (polyphosphates) and pseudovacuoles (poly-beta-oxibutyric acid). Temperature influenced the process of mitotic division and the state of chromatin in bacteria. The described ultrastructural changes Y. pseudotuberculosis may be regarded as natural adaptive reaction to the altered conditions of their residence.     

Ultrastructural changes in the components of the filtration barrier in the glomerular capillaries of a remaining kidney following its temporary ischemia

The components of the filtration barrier of the glomerular capillaries of the rat remaining kidney were studied ultrastructurally 3, 7, 14, 30, 60, 180 and 360 days after exposure to 30 minutes and to 1-2 hours of ischemia. Submicroscopic changes found in the glomerular capillaries and in compensation -adaptive processes occurring in the remaining kidney were ascertained to be dependent on the duration of ischemia and the time elapsed since recirculation in the kidney. After 30-minute ischemia experienced by the remaining kidney the structural alterations in the glomerular capillaries were not remarkable, disappearing 14 days following recirculation, with the emergence by that time of the signs of hyperplasia and hypertrophy of intracellular structures. After raising the time of temporary ischemia of the remaining kidney up to 60 min followed by recirculation, appreciable ultrastructural postischemic disorders were recorded in the components of the filtration barrier of the glomerular capillaries. In addition, the compensation-adaptive processes in the kidney remained suppressed for a longer period of time. All these disorders were particularly demonstrable as a result of 2-hour ischemia. It was also discovered that destructive processes dominated over reparative ones thereby leading to the animals' death at early times of experiment.     

STRUCTURE AND DEVELOPMENT OF EMBRYOS OF EPHESTIA CAUTELLA (WALKER) DURING ANOXIA AND PHOSPHINE TREATMENT

Exposure of Ephestia cautella eggs to anoxic conditions retards the development of the embryo, causing a marked delay in hatching. Phosphine treatment results in little or no hatch delay in surviving embryos and produces characteristic ultrastructural lesions, mainly manifested as changes in mitochondrial organization.     

Effects of patulin on thymus capillary of rats

Patulin is a mycotoxin that is produced by species of Penicillum, Aspergillus, and Byssochylamys molds that may grow on a variety of foods including fruit, grains and cheese. Patulin, at a dose of 0.1 mg kg(-1) bw day(-1) was administered orally to growing male rats aged 5-6 weeks for a period of 60 or 90 days. The dose of patulin used in the present study was based on estimated human exposure levels. At the end of these periods, the thymus glands of patulin-treated and control Wistar rats were removed and ultrastructural changes in capillary cells of the thymus of patulin-treated Wistar rats were determined by electron microscopy. The walls of thymus capillaries of the 60-day patulin-treated rat groups (P-60) exhibited degeneration observable in electron microscopic sections. For example, loss of cytoplasm and mitochondrial cristae of cells, swollen endothelial cells, increased thickness of the basement membrane, closed lumen of capillaries, accumulation of fibrous material at the periphery of the capillaries and nuclear anomalies were seen in these sections. Such degeneration and changes were also observed in sections of capillaries of the 90-day patulin-treated rat groups (P-90). The levels of degeneration of endothelial cell nucleus of P-90 were greater than those of P-60. This study demonstrated the ultrastructural degeneration of thymus capillary cells of patulin-treated rats. The results obtained from this study may provide a guide to research dealing with the toxic effects of patulin on tissue and organ ultrastructure.     

Ultrastructure and histochemistry of rat myocardial capillary endothelial cells in response to diabetes and hypertension

INTRODUCTIONThe streptozotocin [STZ]-induced diabetes and NO-deficient hypertension are widely used experimental modelsfor the investigation of heart failure [1-4]. Cardiac dys-function in both models is consequence of different sig-nal and metabolic dera…     

Changes in the function and ultrastructure of vessels in the rat model of multiple low dose streptozotocin-induced diabetes

In this study we investigated functional changes in the femoral artery and ultrastructural alterations in mesenteric vessels and capillaries in the rat model of multiple low dose streptozotocin (STZ)-induced diabetes. Participation of oxidative stress in this model of diabetes was established by studying the effect of the pyridoindole antioxidant stobadine (STB) on diabetes-induced impairment. Experimental diabetes was induced by i.v. bolus of STZ (20 mg/kg) given for three consecutive days to male rats. At the 12(th) week following STZ administration, the animals revealed typical signs of diabetes, such as polyphagia, polydypsia and polyuria. There was no weight gain in the diabetic groups throughout the experiment. No exitus occurred in any group. Diabetes was characterised with high levels of plasma glucose, no significant changes in lipid metabolism, decreased serum levels of glutathione, increased serum levels of the lysosomal enzyme N-acetyl-beta-D-glucosaminidase (NAGA), injured endothelial relaxant capacity of the femoral artery and alterations in ultrastructure of mesenteric arteries and capillaries. Antioxidant STB in the dose of 25 mg/kg body weight i.p. (5 times per week) did not influence glucose levels, however, it mitigated biochemical, functional and ultrastructural changes induced by diabetes, suggesting a role of reactive oxygen species in diabetes-induced tissue damage.     

Effects of benfluorex-vitamin C supplementation on cutaneous capillaries of diabetic rats

The ultrastructural changes on capillaries of the dermis in diabetic and benfluorex-vitamin C treated diabetic rats have been investigated. Three groups of 21 Wistar albino rats were used in the examination: control, diabetes, and benfluorex-vitamin C treated diabetic rats. Diabetes was induced by injection of streptozotocin. The streptozotocin-induced group was treated for 21 days with vitamin C and benfluorex, of which antidiabetic and antihyperlipidemic effects were experimentally proved. Samples taken from the skin of rats' legs were examined under transmission electron microscopy. Swollen endothelial cells, narrowed capillary lumens, a thickened basement membrane, and fusion of mitochondrial cristae in the capillaries of diabetic rat dermis were seen. In the benfluorex-vitamin C treated group, contrary to the diabetic group, neither signs of degeneration in endothelial cells nor a significant difference with the control group with regard to capillary structure were observed. Amelioration in capillaries appears to be due to benfluorex and vitamin C treatment in diabetes.