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PubMed1999

Ultrastructural interactions in the microvasculature of human endometrial adenocarcinoma.

OBJECTIVES: Our purpose was to study the ultrastructural morphology of the microvasculature of human endometrial adenocarcinoma and to determine the effect of this malignancy on cell-to-cell communication between the components of the microvasculature and with the other tissue compartments of human endometrium. Methods. Multiple cases of human endometrial adenocarcinoma were studied and graded by light microscopy. Six cases of Grade I and six cases of Grade II were selected. Two blocks per case were studied ultrastructurally. RESULTS: In contrast to our expectation that the ultrastructure of tumor vessels would suggest a great deal of proliferation and new vessel formation, we found that tumor vessels displayed a high degree of cellular differentiation, in the form of numerous and varied cell-to-cell contacts, and large amounts of protein production. CONCLUSIONS: The morphology of the microvasculature of endometrial adenocarcinoma suggests an active rather than passive role in tumor vessels.

Adenocarcinoma↗
PubMed1999

Coccolith ultrastructure and biomineralisation

The relationship between calcite biomineralisation and coccolith ultrastructure is analysed across the diversity of calcifying haptophytes. The emphasis is on integration of evidence from crystallographic and ultrastructural studies but additional relevant information from biochemical and phylogenetic work is reviewed. We attempt to identify aspects of ultrastructure which are most likely to be the product of self-organising processes. The principal topics reviewed are heterococcolith rim nucleation, including reassessment of the V/R model; crystal growth regulation in heterococcoliths; holococcolith biomineralisation; and the diversity of other biomineralisation modes in haptophytes. It is concluded that the diverse range of calcareous structures produced by haptophytes probably has a common phylogenetic origin and is produced via operation of a limited set of mainly shared genetic and biochemical pathways. Copyright 1999 Academic Press.

Journal Article↗
PubMed2000

Ultrastructure of sea urchin calcified tissues after high-pressure freezing and freeze substitution.

The improvements brought by high-pressure freezing/freeze substitution fixation methods to the ultrastructural preservation of echinoderm mineralized tissues are investigated in developing pedicellariae and teeth of the echinoid Paracentrotus lividus. Three freeze substitution (FS) protocols were tested: one in the presence of osmium tetroxide, one in the presence of uranyl acetate, and the last in the presence of gallic acid. FS in the presence of osmium tetroxide significantly improved cell ultrastructure preservation and should especially be used for ultrastructural studies involving vesicles and the Golgi apparatus. With all protocols, multivesicular bodies, suggested to contain Ca(2+), were evident for the first time in skeleton-forming cells. FS in the presence of gallic acid allowed us to confirm the structured and insoluble character of a part of the organic matrix of mineralization in the calcification sites of the tooth, an observation which modifies the current understanding of biomineralization control in echinoderms.

Animals↗
PubMed2000

Glutathione and ultrastructural changes in inflow occlusion of rat liver.

BACKGROUND: Liver ischemia/reperfusion is frequently associated with organ injury to which reactive oxygen species contribute. The aim of our study was to evaluate cytosolic and mitochondrial glutathione levels and morphological changes in hepatocytes of rat liver in an experimental model of ischemia/reperfusion. MATERIALS AND METHODS: The experimental procedure consisted of temporary interruption of blood flow to the left lateral and medial hepatic lobes for different lengths of time and, in some cases, subsequent reperfusion. Cytosolic and mitochondrial glutathione levels were evaluated and ultrastructural analysis was carried out for all samples. RESULTS: Ischemic lobes showed ultrastructural changes in relationship with the increase in ischemia time. Total glutathione levels did not show variations in ischemic lobes and sham lobes with respect to control rats during ischemia only. Instead, during reperfusion, significant ultrastructural alterations of the hepatocytes and a significant depletion of glutatione in cytosolic and mitochondrial compartments were evident. The sham lobes also showed a significant glutathione decrement. Increased oxidized glutathione (GSSG) levels were found during ischemia both in ischemic lobes and in sham lobes. During reperfusion GSSG was found to a minor extent, in the cytosolic compartment. In mitochondria GSSG levels were also high during reperfusion. CONCLUSIONS: We conclude that depletion of glutathione contributes to impaired liver after reperfusion following ischemia but depletion of glutathione alone does not induce changes in the morphology of the hepatocytes. Glutathione depletion and a greater quantity of GSSG, even in sham lobes, may indicate a metabolic alteration which spreads to compartments that are not involved in ischemia/reperfusion.

Animals↗
PubMed1999

Ultrastructural characteristics of myocardial and coronary microvascular lesions in Kawasaki disease.

Kawasaki disease (KD) is an acute febrile mucocutaneous lymph node syndrome with multisystemic vasculitis affecting mainly infants and children. Although several studies on cardiovascular lesions in KD have been done at the light microscopic level, the ultrastructural characteristics and incidences of these lesions have not been well defined. In order to investigate the myocardial and coronary microvascular sequelae in KD, we performed an ultrastructural study on endomyocardial biopsy specimens obtained during follow-up from 54 patients who had typical clinical manifestations of KD, of whom 47 had associated coronary aneurysms as demonstrated by coronary arteriography (CAG) or two-dimensional echocardiography in the acute or healed stage. The average age of onset was 2.2 years old and the duration of illness was from 2 months to 23 years. Follow-up CAG showed that the coronary aneurysms persisted in 33 of the 47 patients (8 with associated stenosis) and resolved in the remaining 14 patients. Ultrastructurally, the myocardial changes revealed hypertrophy, various degrees of degeneration, proliferation and abnormality of mitochondria, infiltration of a small number of lymphocytes, and fibrosis. The coronary microvascular lesion was characterized by microvascular dilatation, endothelial cell injury, platelet aggregation with thrombosis, and stenotic lumen with thickened walls in the small arterioles. It persisted after convalescent stage even up to 23 years and closely correlated with the myocardial sequelae. Moreover, significantly increased incidences of myocardial and coronary microvascular lesions were found in patients with coronary artery lesion. These findings suggest the coronary microvascular lesion as a possible underlying factor of persistent sequelae in KD.

Adolescent↗
PubMed2006

Functional ultrastructure of the vascular endothelium: changes in various pathologies.

Biology has revealed that form follows function or function creates the organ. Translating this law at the cellular level, we may say that the ultrastructure follows function or function creates the ultrastructure. The vascular endothelium is an accurate illustration of this rule due to its numerous and many-sided functions carried out by highly specialised cells, structurally equipped for their tasks. Occupying a strategic position between the blood and tissues, the endothelial cell (EC) tightly monitors the transport of plasma molecules, employing bidirectional receptor-mediated and receptor-independent transcytosis and endocytosis, regulates the vascular tone, synthesises and secretes a large variety of factors, and is implicated in the regulation of cell cholesterol, lipid homeostasis, signal transduction, immunity, inflammation and haemostasis. Ultrastructurally, besides the common set of organelles, the characteristic features of the ECs are the particularly high number of vesicles (caveolae) endowed with numerous receptors, transendothelial channels, the specialised plasma membrane microdomains of distinct chemistry, and characteristic intercellular junctions. In addition, by virtue of their number (-6 x 10(13)), aggregated mass (-1 kg), large surface area (-7,000 m2) and distribution throughout the body, the ECs can perform all the assumed functions. The vascular endothelium, with its broad spectrum of paracrine, endocrine and autocrine functions, can be regarded as a multifunctional organ and chief governor of body homeostasis. The ECs exists in a high-risk position. The cells react progressively to aggressive factors, at first by modulation of the constitutive functions (permeability, synthesis), followed by EC dysfunction (loss, impairment or new functions); if the insults persist (in time or intensity), cell damage and death ultimately occur. In conclusion, the ECs are daring cells that have the functional-structural attributes to adapt to the ever-changing surrounding milieu, to use innate mechanisms to confront and defend against insults and to monitor and maintain the body's homeostasis.

Alzheimer Disease↗
PubMed1987

Ultrastructural observations on the effects of different substrates on ischaemic contracture in global subtotal ischaemia in the rat heart.

Ultrastructural morphology was examined in myocardia perfused with different substrates, following the hypothesis that ultrastructural changes or differences would indicate the mechanism of early ischaemic contracture. Substrates used were glucose, acetate and no substrate (substrate-free). Isolated rat hearts were subjected to global low flow ischaemia followed by perfusion fixation at either no contracture, early contracture (5%) or full contracture (100%). Total tissue adenosine triphosphate (ATP) levels were analysed from myocardia of each group. Glucose perfused myocardia did not develop contracture for at least 30 minutes and maintained ultrastructural and ATP normality. Substrate-free and acetate perfused myocardia developed contracture after 10-12 minutes of ischaemia at which time myofibrillar morphology was altered within small sparse foci of developing mild oedema with contracture and hyperextension of myofibrils. ATP levels were normal. At full ischaemic contracture, both substrate-free and acetate perfused myocardia showed severe mitochondrial damage, oedema, myofibrillar contracture and hyperextension with accompanying distortion and swelling of the sarcoplasmic reticulum.

Animals↗
PubMed1991

Ultrastructural and histochemical characterization of marmoset (Callithrix jacchus) Leydig cells during postnatal development.

Leydig cell development was investigated in the marmoset (Callithrix jacchus) testis from 24 h post partum (pp) up to sexual maturity, using ultrastructural and histochemical methods. Electron microscopically three different Leydig cell (LC) types could be distinguished: neonatal, immature and adult LCs. Neonatal LCs exhibited a round nucleus, large tubular mitochondria, abundant smooth endoplasmic reticulum (SER), and few small fat vesicles. The typical immature LCs showed a lobulated nucleus, smaller tubulo-vesicular mitochondria, less SER, and larger fat vesicles. Adult LCs contained an invaginated nucleus, tubular mitochondria, abundant SER, large fat vesicles, and lipofuscin granules. Neonatal Leydig cells occurred from 24 h pp up to 10 weeks pp, immature LCs from 2 weeks pp up to 20 weeks pp, and adult LCs from 20 weeks onwards. The appearance of a new LC population was accompanied by a numeric decrease and occurrence of regressive cells of the previous population. Developmental steps of differentiation were recognizable in the population of immature and adult LCs by the amount of SER (immature LCs), the size of mitochondria (adult LCs), and the morphology of the nucleus at the beginning of their appearance. Activity of 3 beta-hydroxysteroid dehydrogenase (3 beta-HSD) was moderate in immature LCs from 2 weeks pp to 12 weeks pp and strong in adult LCs. Neonatal LCs were not stained nor were immature LCs from 16 weeks to 20 weeks. Comparison of the ultrastructural classification of LCs and the activity of 3 beta-HSD showed that the capacity for steroid biosynthesis does not necessarily include morphological differences. Activity of non-specific esterase (nE) was found in LCs except of the period between 16 and 25 weeks pp. A transient decrease of activity was seen during the first week of life. Both, the phase of decrease and the phase of inactivity were followed by distinct activation of nE. Lipid content and the size of single fat droplets in LCs, as seen with Sudan black staining, varied during postnatal development. Finely stained granules were typical for neonatal LCs, whereas larger droplets were found in immature and adult cells. Particularly high amounts of lipids were seen at one week and between 32-60 weeks pp, which was the regression of neonatal LCs, showing ultrastructurally higher amounts of lipids than intact neonatal LCs. High amounts of lipid during puberty (32-60 weeks pp) accompanied by an activation of nE at the onset of puberty suggest an initiative role in steroidogenesis.(ABSTRACT TRUNCATED AT 400 WORDS)

3-Hydroxysteroid Dehydrogenases↗
PubMed1994

Immunocytochemical and ultrastructural heterogeneities of normal and glibenclamide stimulated pancreatic beta cells in the rat.

When studied morphologically in semi-thin sections in the rat in vivo, pancreatic beta cells displayed heterogeneous immunoreactivities for insulin and amylin, depending on the islet size and the intra islet position of the beta cells. In larger islets, cortical beta cells (beta cells with contacts with all islet cell types and with the exocrine parenchyma) which are located in the periphery were more densely immunostained for insulin and amylin than medullary beta cells (beta cells with contacts only with other beta cells) which are located in the centre of the islet. Ultrastructurally, these findings were accompanied by differences in the number of secretory granules and mitochondria. Beta cells in small islets and at extra-islet sites exhibited a dense immunoreactivity. After administration of glibenclamide, immunoreactivities for insulin and amylin were diminished in a time-dependent manner, decreasing first in medullary and thereafter in cortical beta cells of larger islets. Ultrastructurally, the beta cells exhibited the typical signs of stimulation. A minority of beta cells in small islets and all beta cells in extra-islet locations remained unchanged. Thus pancreatic beta cells under basal and stimulatory conditions in vivo exhibit heterogeneity in hormone content and in ultrastructural features. These differences may represent the basis for a functional heterogeneity of the insulin secretory response of the individual beta cell both in vivo and in vitro in states of normal and impaired insulin secretion. As heterogeneity was observed only among beta cells in islets, while single beta cells surrounded by acinar cells exhibited no changes in insulin immunoreactivity, interactions between beta cells as well as between beta cells and other endocrine cells may be critical for expression of heterogeneity within the beta cell population.

Amyloid↗
PubMed1995

Effect of lysyl hydroxylase inhibitor, minoxidil, on ultrastructure and behavior of cultured rabbit subconjunctival fibroblasts.

BACKGROUND: Minoxidil is an inhibitor of lysyl hydroxylase, an enzyme involved in collagen production, and decreases collagen production in vitro. We investigated the in vitro effects of minoxidil on behavior such as proliferation and migration of rabbit subconjunctival fibroblasts (SCFs). The ultrastructural effect of the drug on SCFs was also examined. METHODS: Proliferation of SCFs and closure of the defect produced in monolayer cultures in the presence or absence of minoxidil was studied. The ultrastructure of SCFs treated with minoxidil was also examined. RESULTS: Minoxidil inhibited SCF proliferation and the closure of the defect produced in monolayer cell sheets. Ultrastructural observations revealed extensive areas of irregularly dilated endoplasmic reticulum in cells treated with minoxidil, indicating the accumulation of protein, probably underhydroxylated collagen precursors, in the cisternae of endoplasmic reticulum. CONCLUSIONS: The results indicated that minoxidil attenuated cellular activities of SCFs such as proliferation and migration in vitro. The exact mechanism of the inhibitory effects of minoxidil on these cellular activities is unknown. The findings suggest that the drug might help to prevent bleb scarring after glaucoma filtering surgery.

Animals↗
PubMed1986

Immunohistochemical and ultrastructural study of anterior pituitary cells in the female Afghan pika, Ochotona rufescens rufescens.

An immunohistochemical study of the anterior pituitary gland of the female Afghan pika was carried out to distinguish the ultrastructural features of GH, PRL, ACTH, TSH and LH cells. The histochemically identified GH cells resembled ultrastructurally oval or round GH cells of the rat laden with large, dense secretory granules. PRL cells were divided into three subtypes based on differences in the diameter of their spherical secretory granules. They lacked polymorphic or irregularly shaped secretory granules. ACTH cells resembled ultrastructurally, in some respects, Siperstein's "corticotrophs" of the rat with peripheral arrangement of secretory granules. However, they were not always stellate, but elongate or angular in shape. The dense secretory granules were concentrated in the peripheral area of cytoplasm. TSH cells were non-stellate, but usually oval in shape, containing the smallest spherical secretory granules (100-200 nm in diameter). Almost all LH cells reacted also with FSH antiserum. They were irregular in shape, sometimes in contact with or surrounded the GH cells. They contained an abundance of medium-sized secretory granules (140-260 nm in diameter) which were larger than those in the LH cells of the female rat throughout the estrous cycle. Large secretory granules in the LH cells of the female pika seemed to be related to the endocrine state of persistent estrus.

Adrenocorticotropic Hormone↗
PubMed1983

The ultrastructure of oesophageal striated muscle in the guinea-pig and marmoset.

The ultrastructural characteristics of oesophageal striated muscle from guinea-pig and marmoset have been examined using transmission electron microscopy and compared with ultrastructural features of skeletal muscle. The findings show that, although similar to skeletal muscle, oesophageal striated muscle exhibits important differences in the arrangement of its muscle fibres and their motor innervation. It was also found impossible to classify oesophageal striated muscle according to the usual ultrastructural criteria since its motor endplates bore a greater resemblance to those of intrafusal skeletal muscle fibres. The consideration of these differences in conjunction with characteristics revealed elsewhere by other techniques confirms the unique nature of oesophageal striated muscle.

Animals↗
PubMed1983

Extensive ultrastructural changes in rat mammotrophs following administration of the dopamine agonist ergocristine-reflecting inhibition of prolactin release.

We have demonstrated an extensive reorganization of organelles in mammotrophs immediately following administration of ergocristine (a dopamine agonist) to estradiol-primed male rats. Our ultrastructural findings are consistent with our previous results that ergocristine can block prolactin release without any noticeable latent period. Following three-week priming of male rats with estradiol implants, ergocristine was administered by a bolus injection through an indwelling cannula. Within two min of its administration, ergocristine induced dramatic changes in the ultrastructure of mammotrophs, i.e., (1) increased numbers of secretory granules, (2) peripheral relocation of rough endoplasmic reticulum which tends to sequester secretory granules, (3) change in location of nucleus and (4) increased numbers of intracellular bodies associated with secretory granules. We suggest that the extensive ultrastructural changes that occurred in such a short period following ergocristine administration may be indications of specific factors associated with blockage of hormone release.

Animals↗
PubMed1982

Endometrial ultrastructure in the early uterine response to blastocysts and artificial deciduogenic stimuli in rats.

The early uterine response to transplanted, delayed and estrogen-activated blastocysts was studied ultrastructurally and compared with that induced by intrauterine instillations of deciduogenic agents (arachis oil, air). The uterine responses to delayed and activated blastocysts showed no ultrastructural or temporal differences. Already within 4 h after transfer to a sensitized uterus, the delayed blastocysts exhibited signs of activation, and both types of blastocysts had started to attach onto an undamaged epithelial lining. Signs of stromal cell differentiation into decidual cells were also seen as early as 4 h after transfer, while the Pontamine-blue reaction did not appear until after 8 h. The results therefore indicate that the transplanted blastocysts induced decidualization atraumatically and that the delayed blastocysts were either deciduogenic already before transfer or rapidly acquired deciduogenic properties after transfer. Artificial decidual induction with oil and air led to damage or death of a large number of cells in the uterine luminal epithelium. Within only 15 min after instillation pronounced signs of cell damage were seen, and later numerous cells were extruded from the epithelial lining. In the stroma ultrastructural signs of decidual cell differentiation and a Pontamine-blue reaction were observed as early as 4 h after induction. It is therefore suggested that oil and air induce decidualization via the epithelium by means of trauma.

Air↗
PubMed1982

Lack of correlation between ultrastructural and pharmacological types of non-adrenergic autonomic nerves.

In order to test the premise that non-adrenergic, non-cholinergic (NANC) autonomic nerves have a distinctive ultrastructural appearance, clearly different from that of cholinergic nerves, a detailed quantitative ultrastructural analysis has been made of the non-adrenergic innervation of 15 tissues thought from pharmacological evidence to be innervated by NANC nerves (rat and rabbit anococcygeus muscles; rabbit hepatic portal vein; extrinsically denervated toad lung); cholinergic nerves (atria of rat, rabbit, guinea-pig and toad); or both (guinea-pig cervical and thoracic trachealis muscle; rabbit rectococcygeus muscle; urinary bladder of rat, rabbit, guinea-pig and toad) in addition to their adrenergic supply. Following fixation with a modified chromaffin procedure allowing identification of adrenergic nerves, large, randomly selected samples of non-adrenergic nerve profiles from each tissue were analysed with respect to numbers, relative proportions, and size frequency distributions of different vesicle classes within the profiles. The neuromuscular relationships within each tissue were also analysed. On the basis of these analyses, it is clear that there are no consistent ultrastructural differences between cholinergic and NANC autonomic nerves: neither proportions nor sizes of the vesicles provide any clue as to the transmitter used by a particular nerve. The great majority of nerve profiles, whether cholinergic or NANC, contain predominantly small clear "synaptic" vesicles. Large filled "peptidergic" vesicles are no more common in most NANC

Adrenergic Fibers↗
PubMed1983

An ultrastructural morphometric study of the papillary muscle of the right ventricle of the cat.

The papillary muscle of the cat heart's right ventricle has not been studied previously with quantitative ultrastructural techniques despite its wide use for functional studies. This tissue was perfusion-fixed, processed for electron microscopy, and morphometric techniques were used to assess the ultrastructural characteristics of the papillary muscle as well as the working myocardial cells. The results of this study were that 73.5% of the papillary muscle was composed of muscle cells, 9.7% of blood vessels, and the remainder of interstitial connective tissue. In the muscle cell the volume fraction of mitochondria was 17.3%, that of myofibrils was 49.8%, and that of the nucleus was 2.0%. The mitochondria to myofibrils ratio was 0.36 and the surface to volume ratio was 0.309. In a quantitative ultrastructural comparison of perfusion and immersion fixed tissue it was found that significant differences in the volume density of the blood vessel lumen existed between the two groups. In addition, there were significant differences in the volume fraction of mitochondria and nucleus between perfusion-fixed and immersion-fixed muscle cells. A concurrent significant decrease between the two groups was also found for the ratio of mitochondria to myofibrils. The perfusion-fixed tissue can be considered to provide only normal baseline data for the papillary muscle of the right ventricle. These data are important as they can be used in future structure-function studies on normal and pathological heart tissue.

Animals↗
PubMed1984

Ultrastructural changes in adrenaline- and SGC-cells after morphine coincide with alterations of adrenaline and dopamine levels.

The effects of morphine on chromaffin cell ultrastructure and catecholamine contents were studied using the adrenal glands from male mice (ICR strain). After 2 h adrenaline was increased 25% from 8.1 to 11.6 mumol/g tissue, followed by a 50% decrease to 5.2 mumol/g between 8-24 h and low values persisting at 72 h. Dopamine increased initially, reaching peak values of 0.5 mumol/g between 8-24 h, but had returned towards control values of 0.29 mumol/g by 72 h. Noradrenaline remained unchanged at 2.5 mumol/gram. Naloxone prevented alterations in adrenaline and dopamine levels. Ultrastructural examination revealed several types of catecholamine-storing cells. Of these the adrenaline and small-granule chromaffin (SGC) cells were more affected by morphine than noradrenaline cells. While the initial elevation of adrenaline 2 h after morphine was not accompanied by significant ultrastructural changes, the decrease after 8 and 24 h was paralleled by a significant (p less than 0.001) loss of adrenaline granules. Signs of active membrane turnover included an increase in the number of vacuoles, and the appearance of numerous coated omega profiles and coated (77.7 +/- 0.6 nm) vesicles. Clusters of synaptic-like vesicles (59.8 +/- 8.2 nm), slightly larger than neuronal vesicles (45.4 +/- 6.4), increased in the SGC-cells. After 72 h, the chromaffin granules in adrenaline cells remained low in numbers and were heterogeneous in electron density. Many synaptic-like vesicles were aligned along the SGC-cell membranes where only few chromaffin granules (109.3 +/- 20 nm) remained. Thus, continuous morphine exposure for 8-72 h increases the turnover of storage granules in adrenaline and SGC-cells with less effect on the noradrenaline cells which maintain catecholamine levels as indicated by biochemical analysis.

Adrenal Medulla↗
PubMed1985

The ultrastructural and biosynthetic characteristics of steroidogenic cells in the gonad of Monopterus albus (Teleostei) during natural sex reversal.

The ultrastructural and biosynthetic characteristics of the steroid cells in the gonad of Monopterus albus have been studied. Ultrastructural features related to steroidogenesis have been identified in the interstitial Leydig cells, Sertoli cells, granulosa cells and thecal cells, and are especially abundant in the Leydig cells during the mid-intersexual phase. Steroidogenic ultrastructures in the Sertoli cells develop only during the maturation of the spermatogenic cysts, whereas in the granulosa and thecal cells, these features become obvious only during the maturation of the large oocytes. EM evidence also suggests a nutritive function for the Sertoli cells and the granulosa cells. Results of in vitro steroidogenic studies, using either testosterone or progesterone as a precursor, show a predominant conversion to androstenedione and 5 alpha-reduced compounds, and suggest a change in biosynthesis from 5 alpha-reduced products to androstenedione during sex reversal. 11-Ketotestosterone (11KT) has been identified, but not 11 beta-hydroxytestosterone. Production of 11KT is high in the late intersexual and the male phases, but a lack of a marked variation in 11KT production between the early and the mid-intersexual phase suggests that this steroid is not a trigger for natural sex reversal in Monopterus.

Androgens↗