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PubMed1981

Ultrastructural features of the carotid body after in vitro experiments: correlation with physiological results.

We have studied the ultrastructure and physiological properties of the rabbit carotid body superfused in vitro. After 3 h superfusion, the ultrastructural features of the carotid body cells, nerve fibres and nerve endings are similar to those observed after in vivo perfusion with fixative. After 5 h superfusion, the fluorescence of type I cells and sympathetic post-ganglionic nerve fibres appears normal, as demonstrated by the Falck method. After 6 h superfusion, some type I cells are characterized by a highly vacuolated cytoplasm whereas most of the nerve fibres and nerve endings still show a normal ultrastructure. Damaged cells are not more abundant in the centre of the organ than in the surface layer. Recordings from chemoafferent units demonstrate the possibility of superfusing the carotid body with an air-equilibrated medium without any noticeable excitation. Large and reproducible responses to hyperoxic and hypoxic superfusions are recorded. It is concluded that the in vitro superfused rabbit carotid body is a reliable and useful preparation for studying the mechanism of chemoreceptor excitation.

Animals↗
PubMed1985

Ultrastructural effects of ulcerogens.

Agents such as ethanol, aspirin, bile acids, and hypertonic urea and glucose, are capable of breaking the physiological gastric mucosal barrier and may cause ultrastructural injury to the epithelial cells within several minutes of exposure. Ethanol at any pH, and aspirin and bile acids at acid pH, are lipid soluble and diffuse rapidly into surface epithelial cells where a sequence of injury can be documented by electron microscopy. First, the nuclear chromatin becomes clumped and the density of the cytoplasmic ground substance decreases. Second, mitochondria become swollen and the apical cell membrane is distorted. Finally, the apical cell membrane ruptures and the cell disintegrates. Throughout this sequence, the tight junctions between cells appear morphologically intact. In contrast to lipid soluble agents, hypertonic urea and glucose do not diffuse well into surface epithelial cells. Although these agents also cause rapid changes in transmucosal potential difference and ion fluxes, their ultrastructural effects are quite different. Hypertonic urea and glucose initially cause small blebs within the tight junctions and larger vacuoles within the cytoplasm of surface epithelial cells, while the remainder of the cell structure appears normal. More severe injury is characterized by more vacuolization and eventual disruption of epithelial cells. These changes presumably are secondary to osmotic shifts of fluid and electrolytes. Although the 'cytoprotective' effects of prostaglandins have been well described, there is virtually no information at the ultrastructural level concerning the protective effects of prostaglandins with regard to these ulcerogenic agents.

Animals↗
PubMed1981

Liver arterialization improves hepatocytes ultrastructure in rats with portacaval shunts.

The effect of arterialization (ART) of the distal stump of the portal vein after portacaval shunt (PCS) on bile formation and liver ultrastructure was assessed. ART using the left gastric artery was performed in male Wistar rats. Animals were sacrificed 3 weeks later. ART prevented body and liver atrophy. However, the liver weight to body weight ratio was significantly decreased when compared to sham PCS (2.5 +/- 0.36 vs 3.22 +/- 0.15). Reduction in total bile secretion (microliter/min) seen following PCS is reversed by ART. ART partly corrected hepatocyte size atrophy and the major ultrastructural abnormalities, namely the irregularity of the nucleus and dilation of the nuclear envelope and of the rough endoplasmic reticulum appearing after PCS. However, mitochondria remained swollen, deformed and enlarged with scission figures. No lesions in connection with ART were seen. This result confirms, at the ultrastructural level, the beneficial effect of ART in PCS.

Animals↗
PubMed1982

Hepatocyte ultrastructure in rats with portacaval shunt. A morphometric study of acinar zones.

The principal reported morphological consequence of portacaval shunt in the rat is liver atrophy. The present study was designed to investigate ultrastructural changes in hepatocytes using electron microscopy morphometry. Two weeks following portacaval shunt, rat livers were fixed by perfusion and hepatocyte organelles from the two opposite zones of the acinus (zones 1 and 3) were quantified. Liver weight/body weight decreased by 50%, hepatocyte-specific volume decreased by 30% (28% in zone 1 nd 35% in zone 3). Estimated sinusoidal space increased, and estimated number of hepatocytes decreased by 50%. Hepatocytes had a normal ultrastructure except for mitochondria. Smooth endoplasmic reticulum-specific surface area was reduced by 65% (zone 3), and rough endoplasmic reticulum surface density was increased in zone 1 only. Mitochondria-specific volume was unchanged but decreased inner and outer membrane-specific surface area in zone 3 suggests in this zone a change in their conformation and possibly their number. Golgi-rich area surface density increased but not significantly. Hepatocyte loss and atrophy and rearrangement of organelles represent a new ultrastructural steady state following portacaval shunt that may help explain the new functional steady state.

Animals↗
PubMed1990

Ultrastructural effects induced by global ischaemia on the AV node compared with the working myocardium. A qualitative and morphometric investigation on the canine heart.

The cardiac conduction system is considered to be particularly resistant to ischaemia. Nevertheless, following open heart surgery with short periods of ischaemia disturbances in AV conduction or ventricular arrhythmia have been reported. We compared the ultrastructure of AV node and working myocardium following 30 min global ischaemia at 25 degrees C, during pure ischaemia and with HTK cardioplegia qualitatively and morphometrically. After 30 min of pure ischaemia, interstitial and intracellular oedema together with considerable changes in organelles in AV nodes predominate over mainly cellular oedema in working myocardium. Sometimes irregular overcontractions of sarcomeres occur in the AV node, though very seldom in working myocardium. In pure ischaemia, mitochondrial swelling is comparable in both types of tissue. Following HTK cardioplegia and 30 min ischaemia, cellular oedema and mitochondrial swelling are significantly reduced in AV nodal cells and working myocardium, but remain more extensive in the AV nodes. Irregularities in the contractile state of sarcomeres are not observed. The extent of the ultrastructural alterations corresponds to the degree of metabolic change in the working myocardium. Thus, despite considerable differences during pure ischaemia and HTK cardioplegia, ultrastructurally the AV nodal cells do not display a greater resistance to ischaemia than working myocardium.

Animals↗
PubMed1986

Gliogenesis in organotypic tissue culture of the spinal cord of the embryonic mouse. I. Immunocytochemical and ultrastructural studies.

The technique of organotypic tissue culture offers an opportunity to observe in vitro complex interactions among glial cells and neurons, leading to the formation of myelin. In the present and accompanying work a combined ultrastructural, immunocytochemical and autoradiographic approach was used in a detailed study of the process of gliogenesis. Using immunocytochemical and ultrastructural criteria, differentiation along the oligodendroglia cell line is seen to be initiated a few days later than along the astroglial line. The sequence and timing of oligodendroglial differentiation both ultrastructurally and chemically follow those described in vivo. Formation of myelin has been demonstrated only by oligodendrocytes in which there is continuity between the perikaryal plasmalemma and myelin membranes. Oligodendroglial maturation culminated with the formation of light, medium and dark oligodendrocytes. The periodic acid Schiff-positive, glial fibrillary acidic protein (GFAP)-negative process of radial glial cells at explantation become GFAP-positive within 3 days, as described in vivo. Many of the astrocytes appear to have been derived from radial glial cells. Large numbers of dark glial cells, similar to the so-called 'intermediate glial cells', were seen. These were found to be astrocytes whose appearance probably reflected reaction to explantation-induced injury.

Animals↗
PubMed1993

Fetal Niemann-Pick disease type C: ultrastructural and lipid findings in liver and spleen.

We present the first ultrastructural study of liver and spleen from a 20-week fetus with Niemann-Pick disease type C in correlation with lipid studies of these tissues. The lipid storage pattern was characteristic of the disease and although the distribution of the lipid storage was similar to that of affected children, ultrastructural studies emphasized that many inclusions were qualitatively different. These are discussed. Concomitant with this complex lipid storage, ultrastructural evidence of cholestasis was observed and the early hyperplasia of pericanalicular microfilaments leads us to question the presence of a toxic metabolite which might induce cholestasis by acting upon microfilaments.

Fetal Diseases↗
PubMed1987

Development of the ultrastructural features of somatostatin-immunoreactive neurons in the rat visual cortex.

The peroxidase-antiperoxidase immunocytochemical technique has been used to examine the development of the ultrastructural features of somatostatin (SRIF)-immunoreactive neurons in the visual cortex of the rat between embryonic day 17 and postnatal day 32. In the adult, stained neurons are distributed in layers II through VI and characterized by an abundance of cytoplasm containing a plethora of organelles, most conspicuous of which are cisternae of granular endoplasmic reticulum organized in parallel arrays. In embryonic tissue, SRIF-positive cells are present in the subplate and in the border between the cortical plate and marginal zone. These cells possess scanty cytoplasm containing a few organelles; synapses onto immunoreactive perikarya and dendrites are evident at this stage. At birth and in early postnatal life, labelled cells are confined to the subplate region. Already at this age a number of cells display signs of ultrastructural features which characterize them in adult life. At the end of the first postnatal week, SRIF-immunoreactive neurons span a considerable spectrum of maturity. At one extreme are a few cells with little cytoplasm surrounding a large nucleus and at the other are the majority of labelled neurons showing abundant cytoplasm including prominent arrays of granular endoplasmic reticulum. Labelled cells first appear in the more superficial layers at the beginning of the second postnatal week and attain a distribution similar to that observed in adult animals at the end of this week. At this time their ultrastructural features closely resemble those of their adult counterparts, and differences in cytoplasmic maturity between superficial and deep labelled cells are not evident. This suggests that the SRIF-producing neurons in the superficial layers begin to express this peptide after they complete their migration and have acquired their morphological features. Maturation proceeds during the third postnatal week; at this stage most cells acquire their mature nuclear and cytoplasmic features and an adult complement of synapses. However, a number of SRIF-immunoreactive cells contain a particularly prominent accumulation of cytoplasmic organelles and appear hypertrophic.

Animals↗
PubMed1977

[Influence of the photoperiod on the ultrastructure of the pineal gland before and during the seasonal genital cycle in the female garden dormouse (Eliomys quercinus L.) (author's transl)].

The pinealocyte of the female garden dormouse presents ultrastructural characteristics correlated with the sexual cycle. In winter, during the period of sexual quiescence, the pinealocyte is very rich in liposomes, myelinic bodies and lysosomes; the same holds during the summer quiescence state. These organelles and a great number of intracellular vacuoles are very well developed in dormice artificially maintained in anoestrous during the normal sexual activity period by light deprivation. In spring liposomes are strongly reduced in animals that are awake and sexually active, whereas the number of "synaptic ribbons" and of densecored vesicles increases. This ultrastructural aspect can be obtained during winter quiescence in animals living at 22 degrees C, under continuous light, and showing early sexual activation. If illumination is prolonged over the seasonal sexual phase dilated cisterns of granular endoplasmic reticulum, filled with proteinaceous material, appear in the cell. It seems that light no more activates, but inhibits gonadostimulator mechanisms. The pinealocyte's ultrastructural elements which are characteristic of a definite sexual state generally develop before this state is fully established. Actually, the functional significance of these organelles is not known.

Animals↗
PubMed1985

[Histological and ultrastructural findings in the healing phase of duodenal ulcer].

To evaluate and further characterize duodenal ulcer healing macroscopical, histological, and ultrastructural criteria were examined in 24 patients with active duodenal ulcer disease under two different treatment schedules. After the endoscopic confirmation of an active duodenal ulcer patients were randomly assigned to treatment with either an antacid (group A) or with an H2 blocker (group B). Tissue specimen were taken during endoscopy from the margin and 1 cm from the ulcer before therapy and from the ulcer scar or the previous ulcerated region after a 4 week treatment. A macroscopic ulcer healing by endoscopic criteria was confirmed in 83% of the patients in group A and in 83% of group B. The prominent histological feature of duodenal ulcer healing was a significant increase of PAS positive epithelial cells. Ultrastructural changes of the duodenal mucosa were still present at the end of the treatment, even in the presence of complete macroscopic healing. The ultrastructural healing process shows constant patterns independent from the type of treatment. The characteristic morphological feature by electron microscopy of the healing duodenal ulcer is the appearance of a metaplastic mucus secreting cell of the antrum-type. The devastated mucous structure during the ulcerative phase regains the normal net-like structure after 4 weeks therapy.

Adult↗
PubMed1988

Specific binding of peanut agglutinin and soybean agglutinin to chondroitinase ABC-digested cartilage proteoglycans: histochemical, ultrastructural cytochemical, and biochemical characterization.

The binding of peanut agglutinin (PNA) and soybean agglutinin (SBA) to cartilage proteoglycans was investigated by histochemical, ultrastructural cytochemical, and biochemical methods. Following aldehyde fixation, specimens of rat epiphyseal cartilage were examined by horseradish peroxidase-labelled lectin cytochemistry with and without prior digestion in chondroitinase ABC. At the light microscope level neither PNA nor SBA exhibited any affinity for cartilage matrix, but became strongly bound following chondroitinase treatment. Similarly, at the ultrastructural level, extracellular matrix granules, presumed to be proteoglycan monomer(s), lacked PNA affinity in undigested specimens, and stained very weakly with SBA. Both PNA and SBA weakly to moderately stained the trans cisternae of the Golgi-flattened cisternae in chondrocytes. The chondrocyte plasmalemma lacked PNA staining, but reacted weakly with SBA. Following chondroitinase digestion, PNA and SBA stained matrix granules, and the cell surface of chondrocytes intensely, whereas the Golgi trans cisternae, the Golgi-derived vacuoles, and multivesicular bodies demonstrated weak to moderate reactivity. Proteoglycan aggregates purified from rat chondrosarcoma and bovine nasal cartilage bound PNA and SBA avidly after digestion with chondroitinase. Undigested proteoglycans lacked affinity for PNA and reacted very weakly with SBA. These results indicate that both PNA and SBA specifically react with chondroitinase-modified oligosaccharide(s) bound to core proteins of cartilage proteoglycans. This provided a specific histochemical and ultrastructural cytochemical procedure for localizing chondroitin sulphate-containing proteoglycans.

Animals↗
PubMed1988

Ultrastructural localization of Tamm-Horsfall protein in human kidney using immunogold electron microscopy.

The ultrastructural localization of Tamm-Horsfall protein (THP) was studied in paraformaldehyde-fixed human renal biopsies. Pre-embedding and post-embedding immunogold labelling techniques were developed utilizing a monoclonal antibody specific for human urinary THP. With the pre-embedding technique, membrane contrast was enhanced by osmification thus allowing precise localization of gold particles. Reasonable tissue penetration of antibodies was achieved without compromising ultrastructural detail. The hydrophilic resin LR White was used for post-embedding labelling to ensure maximum penetration of antibodies. However, sections had only mild osmification and consequently localization of label was less certain. Both labelling techniques gave similar results. THP was found to be associated with two renal cell types. Epithelial cells lining the thick ascending limb of Henle's loop had gold label closely associated with the whole cell plasmalemma, with some of these cells having an apparently random distribution of label throughout the cytoplasm. Only the luminal plasmalemma of epithelial cells lining distal convoluted tubules were found to be labelled. Basolateral membranes and the cytoplasm of these cells were negative. The use of a monoclonal antibody of defined specificity combined with the two immunolabelling procedures represents a precise reliable method for studying ultrastructural localization of THP in the human kidney.

Antibodies, Monoclonal↗
PubMed1985

Early ultrastructural adaptive changes of ileal enterocytes after proximal small bowel resection as determined morphometrically.

The aim of the present study was to evaluate in terms of quantitative measurements whether the well-known histomorphological and functional adaptive changes in the intestinal mucosa after small bowel resection are accompanied by alterations on the ultrastructural level. Therefore, samples of the ileal remnants after a 60% proximal resection were processed for ultrastructural evaluation and analyzed employing point counting planimetry and direct measurements. Microvillus surface area increased from the bottom of the crypts to the villus tips in both resected and sham-operated animals. This increase in microvillus surface area from the crypt to the villus was significantly less pronounced after proximal resection, while there were no changes in the crypt compartment. No significant differences of the relative areas of the nuclei, mitochondria, and the rough endoplasmic reticulum were observed when comparing the different positions along the villus crypt axis in normal and hyperplastic mucosa. In agreement with functional and enzyme histochemical results, these ultrastructural findings provide further evidence for an altered pattern of enterocyte maturation after proximal resection, which is most probably due to an increase in the migration rate of the enterocytes.

Animals↗
PubMed1977

Observations on the regulation of cell volume and metabolic control in vitro; changes in the composition and ultrastructure of liver slices under conditions of varying metabolic and transporting activity.

Liver slices incubated at 1 degree C underwent swelling of both cellular and intercellular compartments, as judged by electronmicroscopy. The ultrastructure showed marked changes, including disorganization of the cytocavitary network and plasma membrane and alterations of mitochondria. Restoration of metabolically favorable conditions (oxygenated medium at 38 degrees C) caused a nearly complete recovery of ultrastructure closely associated with extrusion of water; measurements of inulin space and electronmicroscopy both indicate a recovery of cell volume, with intercellular spaces remaining somewhat expended. The fluid lost was a roughly isotonic solution of Na+ and Cl-, while K+ was reaccumulated in exchange for Na+. Cyanide prevented recovery. Ouabain and oligomycin each partially prevented fluid extrusion, but had little effect on ultrastructural recovery except to induce intracellular vesicles containing particles of thorium dioxide derived from sinusoidal spaces. The vesicles were, however, markedly different in form with each inhibitor. There are, thus ouabain-sensitive and insensitive components of volume regulation; the former appears to depend on the coupled transport of Na+ and K+ and the latter, we suggest, on a secretion of Na+ and Cl- into vesicles which release their contents into the bile canaliculi by an oligomycin-sensitive mechanism. Mitochondria showed conformational changes between orthodox and condensed forms, but these could not be directly related to tissue energy states; the numbers of mitochondrial dense granules bore a closer relation to tissue ATP.

Animals↗
PubMedDate not supplied

Influence of repetitive coronary occlusions on myocardial adenine nucleosides, high energy phosphates and ultrastructure.

We compared the effects of repeated short periods of myocardial ischemia with those of permanent occlusion (canine open-chest) with regard to tissue content of adenine nucleotides, nucleosides, creatine phosphate, and ultrastructure. Coronary occlusion for 3 min followed by a reperfusion period of 7 min was repeated up to a cumulative occlusion time of either 45 or 90 min. After cumulative occlusions of 15, 30, 45, and 90 min, transmural needle biopsies were taken from the ischemic area to be analyzed for adenine nucleotides, nucleosides, creatine phosphate, and ultrastructural changes. At the end of each experiment, tetrazolium salt staining was used for macroscopic detection of myocardial necrosis. These data were obtained with those obtained from dogs with a permanent coronary occlusion of 45 and 90 min, respectively. After repeated coronary occlusions at a cumulative occlusion time of 45 min, macroscopic detection of necrosis was negative, and after 90 min of cumulative coronary occlusion, patchy subendocardial tissue necrosis was found in only one out of 13 dogs, whereas in the group with permanent coronary occlusion, small patchy subendocardial necrosis was found in 95% after 45 min, and after 90 min permanent coronary occlusion, large subendocardial necrotic areas spreading towards the epicardial layers were found in 90% of the hearts. Ultrastructural investigations showed only slight to moderate ischemic injury after 45 and 90 min intermittent coronary occlusion, whereas permanent coronary occlusion produced moderate to severe ischemic injury after 45 min; and 90 min permanent coronary occlusion produced irreversible ischemic injury in all subendocardial tissue samples and in 80% of the subepicardial tissue samples.(ABSTRACT TRUNCATED AT 250 WORDS)

Adenine Nucleotides↗
PubMed1988

Ultrastructural and seasonal aspects of the kidney lymphatic system of hibernating animals.

The kidney lymphatic system of bat, dormouse and marmot consists of intraparenchymal (interlobar, arcuate, interlobular) and extraparenchymal (capsular) vessels sharing common ultrastructural aspects. We did not observe medullary lymphatics. The qualitative and quantitative seasonal changes in the ultrastructure of the lymphatic endothelium represent not only a species-linked feature but also (and mainly) an evident seasonal fluctuation in lymph formation. Furthermore, these ultrastructural changes emphasize the important role played by the different mechanisms involved in the translymphatic movement of proteins and interstitial fluid with particular regard to the 'vesicular route' and intraendothelial channels.

Animals↗
PubMed1982

Ultrastructural effect of penicillin and cycloheximide on Chlamydia trachomatis strain HAR-13.

The effect of cycloheximide and penicillin on the ultrastructural morphology of C. trachomatis strain HAR-13 was examined by electron microscopy. HAR-13 infected McCoy cells were either treated with cycloheximide (1 microgram/ml) or cycloheximide (1 microgram/ml) plus penicillin G (100 U/ml). The studies revealed that cycloheximide alone induced no morphological alterations into the ultrastructure of HAR-13. Both HAR-13 developmental forms, the elementary body and reticulate body, were present inside the treated McCoy cells. The elementary bodies contained the central dense nucleoid and were about 0.3 microns in diameter, while the reticulate bodies were of typical gram negative bacterial morphology and were from 0.5-1.0 microns in diameter. Cycloheximide in combined treatment with pencillin produced giant, swollen reticulate bodies that were 2-4 microns in diameter and in some cases vacuolated. Elementary bodies were noticeably absent. These results indicate that cycloheximide does not alter the morphology of HAR-13. This system is a useful model for studying the ultrastructural morphology of C. trachomatis strain HAR-13.

Animals↗
PubMed1976

The ultrastructural localisation of cadmium.

A modified technique for the ultrastructural localisation of heavy metals is described in this paper. The method involves precipitation of heavy metals as sulphides in the tissue by using (NH4)2 S after brief fixation in glutaraldehyde. The sulphides are, in the presence of a physical developer, then used to catalyse the reduction of silver ions into visible molecular silver. This latter step of physical development has been normally carried out after embedding and sectioning. However, when we followed this method we found that the dark metal sulphide was lost from the tissue during the embedding in epoxy resin. Hence the method was unsuitable for our proposed experiment on the ultrastructural localisation of cadmium. We subsequently modified the technique primarily by treating very thin tissue slices with the developer before dehydration and embedding, thus eliminating any problem from sulphide loss. This modified technique was used to investigate the ultrastructural localisation of cadmium in the kidneys of mice which had been exposed to 50 ppm cadmium in their drinking water for up to eight months. The molecular silver was found to be located mainly in the proximal tubule cells, either as dense clumps in apical vesicles and lysosomes or diffuse grains throughout the cytoplasm of the cells particularly in the basal region. We interpret these results as indicating that cadmium is found in the apical vesicles, lysosomes and cytoplasm of proximal tubule cells.

Animals↗