Lipoblastic meningioma: a light and electron microscopic study

A patient with intracranial lipoblastic meningioma in the right frontal lobe is reported. The tumor was entirely made up of vacuolated cells. The nature of this rare neoplasm has been verified by light and electron microscopic studies.     

Galanin and cholecystokinin in cultured magnocellular neurons isolated from adult rat supraoptic nuclei: a correlative light and scanning electron microscopical study

Cultured magnocellular neurons, isolated from adult rat supraoptic nuclei, were characterized by immunocytochemistry, using the avidin-biotin-peroxidase complex and antisera to vasopressin, oxytocin, galanin and cholecystokinin. Light microscope examination of the immunostained cultures revealed the presence of vasopressin- and oxytocin-like immunoreactivity, as well as neurons containing either galanin- or cholecystokinin-like immunoreactivity. In contrast, no significant galanin- or cholecystokinin-like immunoreactivity could be observed in freshly dispersed cells. Correlative scanning electron microscopical observations in the secondary electron imaging mode revealed that the stained neurons appeared significantly brighter than the unstained structures. Complementary observations with toad brain sections (preoptic area), immunostained for galanin, led to the same result. Considering previous results, it is suggested that the presence of galanin- and cholecystokinin-like immunoreactivity in the cultured neurons and its virtual absence in freshly dispersed cells is indicating a participation of these peptides in the regenerative processes taking place during culture. It is further concluded that the avidin-biotin-peroxidase method is suitable for correlative light and scanning electron microscopical studies of smooth surfaces and cultured cells.     

Clinical, and light and electron microscopical findings in sows with cystitis

The clinical findings, and urinary and morphological changes in the urinary bladder were investigated in 25 sows with a urinary tract infection. Eubacterium suis was isolated from 12 of the sows but not from the other 13. The clinical signs did not always correlate with the morphological changes. The only clinical sign indicating the beginning of cystitis appeared to be a significant bacteriuria. Other urinary changes occurred later when the inflammatory processes were more severe. In contrast with cystitis due to other bacteria, infection with E suis frequently resulted in a macrohaematuria and urinary pH values above 8.0. However, the light and electron microscopical findings in the bladder mucosa were similar in the sows with and without cystitis due to E suis. The transformation of goblet cells and the development of mucin cysts were probably due to the local bladder defence mechanisms. More severe lesions were observed with E suis infections, which resulted in changes in the ureterovesical junctions and in ascending renal infection and uraemia.     

Immunocytochemistry of endothelial nitric oxide synthase in the rat brain: a light and electron microscopical study using the tyramide signal amplification technique

There are many inconsistencies in the literature about the cellular and subcellular distribution of the endothelial isoform of nitric oxide synthase (eNOS) in the brain. We have re-investigated its localization by light and electron microscopical (LM, EM) immunocytochemistry and the NADPH-diaphorase reaction. Using bovine aortic tissue as a positive control the protocols for the fixation and staining procedure were optimized. Only cryosections immersion-fixed with aceton and a mixture of aldehydes exhibited a clear-cut immunostaining. In rat brain tissue the endothelium of the entire vasculature showed immunoreactivity and, in addition to that, the epithelial cells of the choroid plexuses, whereas neurons never displayed any signs of immunostaining. EM immunoprecipitates were seen irregularly distributed in the cytosol or attached to endocellular membranes. EM NADPH-diaphorase histochemistry using the tetrazolium salt BSPT provided incoherent pictures in so far as the reaction product was exclusively bound to membranes. The restriction of eNOS within brain tissue to the vasculature may have implications for the differential significance of NOS isoforms in brain function.     

Paravertebral muscles in experimental scoliosis: a light and electron microscopic study

Experimental structural dextroconvex scoliosis was produced in rabbits by costotransversolisis with transversectomy and releasing of paravertebral muscles between TVII and TX on the right side. Two compensatory curves developed on the upper dorsal and lumbar levels. Biopsies of paravertebral muscles in experimental animals included, besides areas of normal tissue, a considerable derangement of the cell contractile apparatus with sarcoplasmic dilation and eventual cell disintegration and necrosis. Histological changes varied along levels, the convexity being more affected. The severity of changes and reduction in body weight and length were correlated with the degree of scoliosis. A selective atrophy of slow-twitch fibers was observed in experimental animals, especially at the level of the main curve, whereas fast-twitch fiber atrophy was more important caudally. Control animal biopsies always appeared normal. Our experimental model shows an overt participation of paravertebral muscles in the establishment of compensatory processes following scoliosis, although the role that paravertebral muscles play in the etiopathogenesis of human idiopathic scoliosis requires further investigation.     

Regeneration of the node of Ranvier: a light and electron microscope study

Regeneration of the node of Ranvier was investigated in the rat peroneal nerve 10-60 days after nerve crush, by light and electron microscopy. At 10 and 20 days after crush nodes of Ranvier were clearly identifiable by electron microscopy but had a relatively simple structure. At 40 days after crush however nodes were highly differentiated showing specialised features such as paranodal bulbs, nodal constriction of the axon, paranodal Schwann cell mitochondria, nodal Schwann cell microvilli, and nodal gap substance. By light microscopy some nodes were identifiable as early as 20 days after crush. At both 30 and 60 days after crush regenerated internodes were uniformly short (means of 275 micronm and 339 micronm respectively).     

Renal proliferative arteriopathies and associated glomerular changes: a light and electron microscopic study

This presentation reports the light and electron microscopic findings relating to the vascular and glomerular changes in the kidney in a series of 25 patients having malignant hypertension, the hemolytic-uremic syndrome, scleroderma, or toxemia of pregnancy. The pathologic changes were generally similar in each of the diseases studied, the changes being related more to the severity and duration of injury than to the specific disease. Vascular narrowing was due mainly to intimal thickening, and by light microscopy the lesions were categorized as onionskin, mucinous, or fibrous with or without associated elastosis. Intimal erythrocyte extravasation, fibrinoid necrosis, and luminal thrombosis were also seen. Electron microscopy provided additional morphologic information: Myointimal cells were found to be the cellular component in each type of intimal thickening; it was possible to distinguish collagen from large intimal accumulations of basement membrane material; mucinous intimal material was characterized ultrastructurally; and fibrinoid necrosis was identified as a lesion inconstantly associated with cellular necrosis and consisting mainly of fibrinoid material and small deposits of fibrin. It seems likely that there is a common pathogenesis for intimal thickening in a variety of diseases and that this involves endothelial cell damage and increased permeability, leakage of serum and erythrocytes into the intima, and a healing reaction of the vessel wall was developing from migration of smooth muscle cells into the intima with subsequent myointimal cell proliferation and fibrogenesis. A common glomerular change in all diseases studied was a striking accumulation of electron lucent material between the endothelium and the lamina densa of the basement membrane. This lesion was interpreted as a manifestation of acute ischemia.     

Testicular histopathology in congenital lipoid adrenal hyperplasia: a light and electron microscopic study

During the 1980s, interest was shown in North America as to how Intensive Care Nurses use their work time, in response to a shortage of trained nurses. These studies were developed to investigate the amount of nursing time that could be saved by computerised recording systems. Similar pressures are now present in the United Kingdom, but there are no published work load studies of Intensive Care Nurses. This study used a five category tool to examine the work load of nurses in a cardiothoracic ICU. The methodology was designed so that comparison could be made with the earlier American studies. The 36 nurses studied spent 41% of their time in direct nursing care, 22% in patient assessment, 19% in clerical duties, 11% in time outside the unit and 7% in non-nursing duties. These findings were compared with the North American studies. Similarities were found which give some support to the reliability and validity of the tool.     

True synovial metaplasia of breast implant capsules: a light and electron microscopic study

High resolution chromosome analysis, molecular cytogenetics, and study of the association between specific chromosome rearrangements and single gene disorders have provided a chromosomal basis to a number of mendelian diseases. Deletions and duplications of small regions, usually less than 3 Mb in size, result in an alteration of normal gene dosage of a number of unrelated genes physically close to each other and are responsible for contiguous gene syndromes. For example, haploinsufficiency is implicated for del 8q24.1 in Langer-Giedion syndrome, del 17p13.3 in Miller-Dieker syndrome, and del 22q11.2 in DiGeorge and Velo-cardiofacial syndromes. Another chromosomal mechanism causing mendelian phenotypes is translocation, which may eventually interrupt a disease gene. It is assumed that translocation breakpoints are running through a relevant gene, hindering the production of the gene product. An example is breakage 16p13.3 associated with Rubinstein-Taybi syndrome. Females with X/autosome translocations have an almost exclusive inactivation of the normal X. Interruption of a disease gene in the translocated X causes the expression of a mendelian phenotype in the presence of an allelic recessive mutation onto the nonrearranged X. Finally, if a human gene shows exclusive expression from a single parental homologue, ie, it is imprinted, deletion of the chromosomal segment containing the active allele results in structural monosomy and functional nullisomy. This situation is illustrated by Prader-Willi and Angelman syndromes. Over seventy human genes have been precisely assigned to chromosomal regions using a cytogenetic approach. Chromosome techniques combined with molecular methods have proved to have powerful and sensitive diagnostic capabilities.     

Oxytocinergic innervation to the upper thoracic sympathetic preganglionic neurons in the rat. A light and electron microscopical study using a combined retrograde transport and immunocytochemical technique

A new pH indicator, seminaphthofluorescein (SNAFL)-calcein acetoxymethyl ester, was used for intracellular pH (pHi) measurement in living MDCK cells with a laser scanning confocal microscope (LSCM) equipped with an Argon/Krypton laser and dual-excitation and dual-emission (FITC/Texas Red) filter set. SNAFL-calcein excitation maxima are approximately 492/540 nm (acid/base) and emission maxima are approximately 535/625 nm (acid/base) with a pKa value at approximately 7.0. The absorption/emission spectra of SNAFL-calcein indicate that the ratio of emission intensities of its basic/acidic forms is pH dependent. With an Argon/Krypton LSCM, we were able to monitor the acidic and basic forms of this dye simultaneously using dual-excitation (488/568 nm) and dual-emission (525-614 nm/> or = 615 nm) wavelengths (lambda s). The simultaneous dual-excitation/emission LSCM system allows for efficient recording of pHi dynamics (time resolution approximately 1 sec) in living cells. We have analyzed emission stability of the dye at different temperatures (22 degrees C and 37 degrees C) and constant pH, and at the same temperature (22 degrees C) but various pHs (6.6, 7.0, and 7.4). Bleaching rate is slightly higher at 37 degree C than that at 22 degrees C. The basic form of the dye (lambda Em approximately 625 nm) has a slightly higher bleaching rate than the acidic form (lambda Em approximately 535 nm) in standard culture medium (pH 7.3) at either 22 degree C or 37 degrees C. The pHi in MDCK cells calculated from ratio images (535 nm/625 nm) was 7.19 +/- 0.03 (mean +/- SEM, n = 20). Calibration experiments show that the useful pH range of SNAFL-calcein appears to be between 6.2 and 7.8, as the dye is difficult to calibrate outside this pH range.     

Prolactin-secreting pituitary tumor in early adolescence: hormonal and electron microscopical studies

A 13-year-old boy was evaluated for an enlarged sella. There were no consistent visual field defects, and carotid arteriograms and pneumoencephalograms showed no extrasellar abnormality. The endocrine workup demonstrated a subnormal growth hormone reserve. The only other, but most striking abnormality, was an excessively high serum prolactin level, which was partially suppressed with levodopa. A chromophobe pituitary tumor was removed that had histological features suggestive of malignant neoplasm. Characteristics of a prolactin-secreting tumor were confirmed by electron microscopy. The serum prolactin levels decreased substantially after surgery and further after a course of pituitary irradiation; however, they continue to be elevated above normal. Prolactin determinations play in integral part in the evaluation for a possible pituitary tumor-not only for diagnostic purposes, but also to provide a parameter of future tumor activity in an established case. Electron microscopical studies are helpful in identifying the tumor as source of the excessive prolactin secretion.     

Structure of a juxtaglomerular cell tumor: the presence of a neural component: a light and electron microscopic study

A 15-year-old girl with hypertension, markedly elevated plasma renin activity, and normal aortogram had a well encapsulated tumor nodule removed from the right kidney. Following surgery, the plasma renin activity and blood pressure became normal and have remained so for the past 12 months. The tumor consisted of juxtaglomerular cells filling the interstitium between endothelium-lined vascular spaces. Electron microscopy disclosed the presence in the interior of the tumor, of unmyelinated nerve bundles with varicosities containing the small, densely cored vesicles characteristic of adrenergic nerves. Nerve terminals were in contact with the juxtaglomerular tumor cells. No basement membrane material was interposed between the nerve endings and the tumor cell; the width of the gap between the two plasma membranes was approximately 150 A. The presence of sympathetic fibers in the juxtaglomerular cell tumor underscores the close biologic relationship between the sympathetic and renin systems.     

Vacuolated meningioma. A light and electron microscopic study

Two unusual cases of meningioma with extensive vacuolization have been studied by light and electron microscopy. There were two kinds of vacuoles in the tumor cells which had the characteristic ultrastructure of meningioma as well. The smaller intracytoplasmic vacuoles were lipid droplets, while the larger, more prominent vacuoles were found to be extracellular spaces probably containing plasmatic fluid. The tumor cells were very much stellate with extremely thin and long cytoplasmic processes having desmosome junctions and forming cavernous intercellular spaces, some of which contained collagen fibers and fibrils. Although the xanthomatous change has been well known, the latter features provide a resonable interpretation for the histology of the present tumors and fat-negative vacuoles in the ordinary meningiomas. The picture may be recapitulation of the subarachnoid structure. Furthermore, recognition of this type of meningioma is practically important especially in frozen section diagnosis not to misinterpret the tumor as liposarcoma, chordoma or metastatic adenocarcinoma.     

Induction of cytosolic NADPH-diaphorase/nitric oxide synthase in reactive microglia/macrophages after quinolinic acid lesions in the rat striatum: an electron and light microscopical study

There is increasing evidence that Ca2+ release from sarcoplasmic reticulum (SR) of mammalian skeletal muscle is regulated or modified by several factors including ionic composition of the myoplasm. We have studied the effect of Cl- on the release of Ca2+ from the SR of rabbit skeletal muscle in both skinned psoas fibers and in isolated terminal cisternae vesicles. Ca2+ release from the SR in skinned fibers was inferred from increases in isometric tension and the amount of release was assessed by integrating the area under each tension transient. Ca2+ release from isolated SR was measured by rapid filtration of vesicles passively loaded with 45Ca2+. Ca2+ release from SR was stimulated in both preparations by exposure to a solution containing 191 mm choline-Cl, following pre-equilibration in Ca2+-loading solution that had propionate as the major anion. Controls using saponin (50 microg/ml), indicated that the release of Ca2+ was due to direct action of Cl- on the SR rather than via depolarization of T-tubules. Procaine (10 mM) totally blocked Cl-- and caffeine-elicited tension transients recorded using loading and release solutions having ([Na+] + [K+]) x [Cl-] product of 6487.69 mm2 and 12361.52 mm2, respectively, and blocked 60% of Ca2+ release in isolated SR vesicles. Surprisingly, procaine had only a minor effect on tension transients elicited by Cl- and caffeine together. The data from both preparations suggests that Cl- induces a relatively small amount of Ca2+ release from the SR by activating receptors other than RYR-1. In addition, Cl- may increase the Ca2+ sensitivity of RYR-1, which would then allow the small initial release of Ca2+ to facilitate further release of Ca2+ from the SR by Ca2+-induced Ca2+ release.     

Phakomatous choristoma of eyelid: electron microscopical confirmation of lenticular derivation

This article presents the sixth recorded example of phakomatous choristoma of the eyelid. The tumor occurred in a 4-month-old boy and was located in the lower lid near the inner canthus. The findings from light microscopy included epithelial, tubular structures with associated patches of thick, irregular basement membrane. The results of electron microscopy (ie, epithelial cells with a scarcity of organelles, homogeneous type of basement membrane, cytoplasmic microfilaments, segments of fascia occludens, and degenerated cells with peculiar interdigitations of their plasmalemmas) are all consistent with lenticular derivation, as originally proposed by Zimmerman.     

The connection from cortical area V1 to V5: a light and electron microscopic study

Area V5 (middle temporal) in the superior temporal sulcus of macaque receives a direct projection from the primary visual cortex (V1). By injecting anterograde tracers (biotinylated dextran and Phaseolus vulgaris lectin) into V1, we have examined the synaptic boutons that they form in V5 in the electron microscope. Nearly 80% of the target cells in V5 were spiny (excitatory). The boutons formed asymmetric (Gray's type 1) synapses with spines (54%), dendrites (33%), and somata (13%). All somatic targets and some (26%) of the target dendritic shafts showed features characteristic of smooth (inhibitory) cells. Each bouton formed, on average, 1.7 synapses. The larger boutons formed multiple synapses with the same neuron and completely enveloped the entire spine head. On most dendritic shafts and all somata the postsynaptic density en face was disk-shaped but in about half the cases the reconstructed postsynaptic densities of synapses on spines appeared as complete or partial annuli. Even in the zones of densest innervation only 3% of the asymmetric synapses were formed by the labeled boutons. Although the V1 projection forms only a small minority of synapses in V5, its affect could be considerably amplified by local circuits in V5, in a way analogous to the amplification of the small thalamic input to area V1.     

Cellular proliferation in vasa rectae in acute tubular necrosis. A histochemical and electron microscopical study

The vasa rectae of the renal cortico-medullary junction were studied in cases of acute tubular necrosis. Although routine light microscopical observations suggested a heterogeneous population of hematopoietic cells, further studies revealed two groups that showed (1) a major fraction, consisting of the lymphoplasma-cytic series with varying stages of maturation, and (2) a minor fraction of granulocytic precursors. The possible importance of this phenomenon is discussed.     

Calretinin immunoreactivity in the cerebral cortex of the lizard Psammodromus algirus: a light and electron microscopic study

The present study describes the distribution and structural features of calretinin-immunoreactive neurons and fiber plexuses in the cerebral cortex of a lacertid lizard, at the light and electron microscopic levels, and also examines the colocalization of calretinin with parvalbumin and gamma-aminobutyric acid (GABA) in certain cortical regions. Calretinin-immunoreactive neurons are present throughout the cerebral cortex of Psammodromus and can be classified according to morphological and neurochemical criteria. Neurons in the medial cortex are small, spine-free and lack parvalbumin, whereas in the lateral cortex, calretinin-immunoreactive neurons display sparsely spiny dendrites and also lack parvalbumin. The dorsomedial and dorsal cortices contain most of the calretinin cortical neurons, which were located almost exclusively in the deep plexiform layer. These neurons are large, with an extensive spine-free dendritic tree. Most of the calretinin-immunoreactive neurons of dorsomedial and dorsal cortices are GABAergic and contain parvalbumin. Calretinin-immunoreactive fibers form two main afferent systems in the cortical areas. One probably intrinsic inhibitory system, arising from the calretinin and parvalbumin GABAergic neurons in the dorsomedial and dorsal cortices, makes symmetrical synapses on the soma and proximal dendrites of neurons located in the cell layers of the same cortical areas. The other system is formed by extremely thin axons running within the superficial plexiform layers of the medial, dorsomedial and dorsal cortices. These axons make asymmetrical synapses on dendrites or dendritic spines. We suggest that this system, probably extrinsic excitatory, arises from neurons located in the basal forebrain.