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.     

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.     

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.     

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.     

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.     

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.     

Identification of orbital lymphatics: enzyme histochemical light microscopic and electron microscopic studies

The presence of orbital lymphatics in the primate model is demonstrated using light and electron microscopic enzyme histochemistry. In addition, strictly morphological definitions of lymphatics, such as discontinuous basal lamina, thin and irregular walls, anchoring filaments, and attenuated endothelial cell cytoplasm, were applied. This study confirmed the presence of conjunctival lymphatics reported by others. It also clearly demonstrated the presence of orbital arachnoid and lacrimal gland lymphatics that have not been previously described. A few areas of the extraocular muscles and connective tissue at the orbital apex also showed evidence of the presence of lymphatic vessels. Additional work is needed to define the nature and extent of orbital lymphatics as well as their connection to the extraorbital lymphatic system.     

Malignant carotid body paraganglioma: light and electron microscopic study of the tumor and its metastases

A right carotid body paraganglioma (CBP) was removed from a 30-year-old female after finding metastases to cervical lymph nodes. The tumor and its metastases were studied by light and electron microscopy to determine the neoplastic cell type. Light microscopy confirmed the presence of chief cells but was inadequate alone to exclude sustentacular cells. By electron microscopy, only chief cells were found in both the primary and secondary tumors. This is the first report of an ultrastructural study of a metastasis from a malignant CBP. From our observation, we suggest that CBP be defined as a proliferation of chief and sustentacular cells. Electron microscopy is essential to determine the cell types present and thereby help classify the lesion as a tumor or hyperplasia of the carotid body.     

Characterization of apoptosis in intestinal ischaemia-reperfusion injury--a light and electron microscopic study

The curiously consistent localization of cerebellar cortical damage in chronic alcoholism is re-evaluated in the light of selective damage, with a similar topography in the cerebellar vermal region, in superficial siderosis in man and in experimental animals exposed to certain toxic substances. Attention is drawn to the capacity for Purkinje cell dendrites and Bergmann glia to extract materials from the CSF, and to the close anatomical relationships of the susceptible lobules I-II, IX and X to the roof of the IVth ventricle and to the cistern of the great cerebral veins. This restriction of damage to vermis and paravermis may reflect some compartmentalization of CSF flow within leptomeninges, consistently increasing exposure of these cerebellar surfaces to materials circulating in the CSF. In other circumstances when this pattern of damage is encountered it raises the question as to whether other environmental agents, gaining access to the CSF, may be similarly distributed.     

Glucagon- and NPY-related peptide-immunoreactive cells in the gut of sea bass (Dicentrarchus labrax L.): a light and electron microscopic study

The recent development of specific competitive inhibitors of the hydroxymethylglutaryl coenzyme A (HMG-CoA) reductase such as lovastatin, simvastatin, pravastatin and fluvastatin has provided an important new and effective approach to the treatment of hyperlipidaemia and atherosclerosis. These agents are designed to be hepatoselective because the primary site of cholesterol synthesis is the liver and peripheral inhibition of cholesterol synthesis would be more likely to cause adverse drug effects. In this review, Bettina Hamelin and Jacques Turgeon discuss how specific physico-chemical and pharmacological properties (first-pass effect or carrier-mediated uptake) confer hepatoselectivity to either lipophilic or hydrophilic HMG-CoA reductase inhibitors.     

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.     

Space flight effects on skeletal bones of rats (light and electron microscopic examination)

In the light and electron microscopes, long tubular bones of Wistar rats that were flown for 22 d onboard the Cosmos-605 biosatellite and were exposed to a ground-based simulation experiment were examined. About half of the flight rats showed osteoporosis of metaphyses which was usually combined with a decrease of the mass of the primary spongiosa in the vicinity of the epiphyseal cartilaginous plate. This gives evidence that the growth of the bones could have been inhibited in flight. The light and electron microscopy of bones of flight rats revealed wide osteocyte lacunae which could have been produced by perilacunar osteolysis. In the simulation experiment, reduction in the metaphyseal spongiosa occurred only in one-third of the rats and was less pronounced than in flight rats; no decrease of the mass of the primary spongiosa near the cartilaginous plate was noted. Histological investigation of bones 27 d postflight demonstrated that that time period was not enough to eliminate all the changes in the bones tested.     

Localization of cholecystokinin-like peptide in neuroendocrine cells of mammalian lungs: a light and electron microscopic immunohistochemical study

Mixing of starved cells of complementary mating types of Tetrahymena thermophila induces shortening of their longitudinal length within 10 min of mixing. This early morphogenetic transformation in preconjugant sexual interaction (costimulation period) was named "costimulation-induced rounding" (CIR). CIR is the earliest morphological change that has ever been found in the costimulation period and differs from "synchronous rounding" in the vegetative cell cycle, because CIR cells are still able to form food vacuoles, while cells in synchronous rounding do not have this ability. When sexual cell-to-cell collisions between two mating types were hampered by unidirectional stirring for 20 min after mixing of the two mating types, both CIR and conjugation were delayed by 20 min. When secreted materials needed for the onset of costimulation were removed by washing the cells with 10 mM Tris-HCl, pH 7.4, before mixing the two mating types, both CIR and conjugation were delayed by about 30 min. CIR-like rounding was not induced by cell-free medium either from the opposite mating type or from mixed costimulated cells. These results indicated that CIR is induced when cells are activated to form conjugating pairs by cell-to-cell collisions between complementary mating types in the presence of secreted molecules.     

The pathology of the atrophy/hypertrophy complex (AHC) of the liver. A light microscopic and immunohistochemical study

The term, atrophy/hypertrophy complex (AHC) of the liver, denotes a distinct combination of hepatic atrophy and hypertrophy occurring in situations of significant impairment of bile flow and/or portal or hepatic venous blood flow. In the lobes or segments concerned atrophy ensues, whereas areas not or less involved develop compensatory hypertrophy, resulting in a characteristic gross deformity of the organ and, in some instances, in rotation of the liver around a virtual hilar axis. As recognition and early detection of AHC have a strong implication on the treatment of several hepatobiliary diseases, adequate combined clinical, radiological and histopathological strategies have to be used in order to arrive at a correct diagnosis. The present investigation was designed to analyze the morphology of AHC in detail and to define lesion patterns having the highest predictive value. For atrophy, the following features were highly characteristic: 1) Advanced septal fibrosis with or without nodular change of parenchyma; 2) Biliary piecemeal necrosis with formation of vascular structures; 3) Ductular proliferations, frequently extending into septa and involving the parenchyma; 4) Capillarization of sinusoids with type IV collagen deposition in Disse's space; 5) Factor VIII-associated antigen expression by sinusoidal endothelia; 6) a seemingly paradoxical increase of proliferative activity of hepatocytes as based on PCNA staining. The severity of lesions in atrophy was related to the type of underlying disease, in that the changes were clearly more expressed in situations of longstanding obstruction due to benign disease. Using a set of well-defined morphological parameters, atrophy can be reproducibly distinguished from hypertrophy in biopsy material from AHC.     

Immunocytochemical localization of substance P receptor in rat periaqueductal gray matter: a light and electron microscopic study

The distribution of substance P receptor (SPR) protein in the rat periaqueductal gray matter (PAG) was investigated with a polyclonal antibody in the four subdivisions obtained by cytochrome-oxidase histochemistry (Co-hi). At light microscopic analysis, immunoreactivity appeared particularly dense in the dorsal subdivision of the PAG, was less intense in the other subdivisions, and formed several longitudinally organized columns. SPR-like immunoreactivity (SP(R-i)) was localized mostly to cell bodies and dendrites of small and medium-sized neurons, which constituted about 6% of the total neuronal population of the PAG. At the electron microscopic level, SP(R-i) could be observed on postsynaptic as well as on nonsynaptic regions of both cell bodies and dendrites. A small proportion of axons (4.2%) and axon terminals (5.3%) showed SP(R-i), the majority of labeled axon terminals, amounting to about 70% of synapsing elements, formed asymmetric synapses with dendrites. Rare astroglial processes displaying SP(R-i) were also observed scattered throughout the neuropil of all PAG subdivisions. Our observations suggest that 1) also in the PAG, SP may act in a diffuse, nonsynaptic manner, probably on targets that are distant from its sites of release; and 2) SP may modulate excitatory neurotransmission acting presynaptically on those labeled axons that form asymmetric synapses.     

Idiopathic membranous glomerulonephritis associated with diabetes mellitus: light, immunofluorescence and electron microscopic study

The present study described 3 patients with idiopathic membranous glomerulonephritis associated with diabetes mellitus. Clinical characteristics of the 3 patients contrasted with diabetic glomerulosclerosis in the following manner: absence of diabetic retinopathy and neuropathy, and presence of nephrotic syndrome associated with relatively short duration of diabetes mellitus. Renal histology showed the characteristic changes of membranous glomerulonephritis along with those of diabetic glomerulosclerosis. Immunofluorescent studies demonstrated a granular pattern of IgG and C3 deposits along the glomerular capillary wall. Electron microscopic study also demonstrated thickening of glomerular basement membrane and increase of mesangial matrix as well as the presence of electron-dense deposits primarily in the subepithelial and mesangial areas.     

Obstructive lesions of distal mesenteric arteries. A light and electron microscopic study

Two cases of "nonocclusive" intestinal infarction are reported. No thrombosis or significant atherosclerosis was identified and proximal mesenteric arteries were widely patent. However, distal mesenteric arteries were thickened and had pinpoint lumens. Light microscopic findings suggested that this marked luminal narrowing was due to prominent intimal fibromuscular proliferation, medial hypertrophy and mild structural disarray, focal periarterial fibrosis, and transmural elastosis. Electron microscopic findings indicated that the endothelium was normal but the basal lamina was irregularly thickened. The predominant cellular component of the thickened intima consisted of smooth muscle cells, and smooth muscle cells of the media were seen to migrate through an extensively disrupted and degenerated internal elastic lamina. Deposits of young elastic fibers, collagen, and ground substance were also noted, particularly in the intima. The need for careful sectioning and microscopic examination of small distal mesenteric arteries in cases of so-called nonocclusive intestinal infarction is emphasized.     

Muscarinic receptor subtypes in the lateral geniculate nucleus: a light and electron microscopic analysis

Neural activity in the dorsal lateral geniculate nucleus of the thalamus (DLG) is modulated by an ascending cholinergic projection from the brainstem. The purpose of this study was to identify and localize specific muscarinic receptors for acetylcholine in the DLG. Receptors were identified in rat and cat tissue by means of antibodies to muscarinic receptor subtypes, ml-m4. Brain sections were processed immunohistochemically and examined with light and electron microscopy. Rat DLG stained positively with antibodies to the m1, m2,and m3 receptor subtypes but not with antibodies to the m4 receptor subtype. The m1 and m3 antibodies appeared to label somata and dendrites of thalamocortical cells. The m1 immunostaining was pale, whereas m3-positive neurons exhibited denser labeling with focal concentrations of staining. Strong immunoreactivity to the m2 antibody was widespread in dendrites and somata of cells resembling geniculate interneurons. Most m2-positive synaptic contacts were classified as F2-type terminals, which are the presynaptic dendrites of interneurons. The thalamic reticular nucleus also exhibited robust m2 immunostaining. Cat DLG exhibited immunoreactivity to the m2 and m3 antibodies. The entire DLG stained darkly for the m2 receptor subtype, except for patchy label in the medial interlaminar nucleus and the ventralmost C laminae. The staining for m3 was lighter and was distributed more homogeneously across the DLG. The perigeniculate nucleus also was immunoreactive to the m2 and m3 subtype-specific antibodies. Immunoreactivity in cat to the m1 or m4 receptor antibodies was undetectable. These data provide anatomical evidence for specific muscarinic-mediated actions of acetylcholine on DLG thalamocortical cells and thalamic interneurons.