Cerebrovasculature permeability changes following experimental cerebral angiography: A light- and electron-microscopic study

Morphological alterations of the cerebral vasculature as related to the permeability of plasma proteins and angiographic contrast media following unilateral cerebral angiography were studied. Both Evans blue albumin and horseradish peroxidase were employed as protein tracers for light and electron microscopy investigation respectively. Grey matter regions of the cerebral cortex, cerebellum, corpus striatum, hippocampus and midbrain showed the most extensive and consistent leakage of these protein tracers. The most extensive penetration of EBA was noted at 1 hr following cerebral angiography as compared to the 5 or 30 min sample times. Permeability changes were noted in small venules and arterioles as well as capillaries. The extent of permeability, however, was appreciably greater in the capillaries as evidenced by rapid extravasation of HRP into the surrounding neuropil extracellular spaces. The glial basement membrane surrounding the perivascular spaces of small venules and arterioles precluded rapid penetration of HRP into the neuropil interstitium. Opening of the tight junctions between the endothelial cells was primarily responsible for the extravasation of HRP in all vessel types. Furthermore, it is our opinion that the hyperosmolar nature of the contrast medium is responsible for opening of these tight junctions.     

Olivary hypertrophy in a case with palatal myoclonus: light- and electron-microscopic study

This is a report on the ultrastructural finding of the olivary hypertrophy in a case with palatal myoclonus. By light microscopy two types of neuronal changes were observed in the inferior olivary nucleus, i.e. the central chromatolysis and cytoplasmic vacuolation. Both types were also recognized by electron microscopy and the cytoplasmic vascuolation was identified as the vesiculated endoplasmic reticulum. In the reactive astrocytes, mitochondria were strikingly proliferated.     

The development of the corpus callosum in cats: a light- and electron-microscopic study

Changes in the size and shape of the corpus callosum (CC)--and in number, size, and structure of callosal axons--between embryonic day 38 (E38) and postnatal day 150 (P150) were studied by light and electron microscope in 25 kittens. The development of the CC was divided into three phases: 1. Embryonic development (E38, 53, 58): At E38, only part of the body of the CC was formed. At E53 and E58, the CC was still very short, but its different parts (genu, body, and splenium) had formed. The cross-sectional callosal area (CCA) was 5.4 mm2 at E53 and 5.6 mm2 at E58. The CC contained 46.3 and 56.4 million axons at E53 and E58 respectively. Mean axon diameters were 0.26 micron at E53 and 0.27 micron at E58. 2. Early postnatal development (P4, 9, 15, 18, 21, 26): The CC at P4 was much longer than at E58 and still slightly elongated during this phase; CCA reached 8.55 mm2 at P4 and 8.88 mm2 at P26. There was a substantial axonal loss (66.8 million at P4 and 52.6 million at P26). From P15 onward, premyelinated and myelinated axons were seen. Mean axon diameter increased from 0.30 micron at P4 to 0.33 micron at P26. 3. Late postnatal development (P39, 57, 92, 107, 150). The CC grew dramatically in both length and thickness, the latter especially in the genu. CCA was 10.1 mm2 at P39 and 15.3 mm2 at P150. The number of axons still decreased (46.5 million at P39 and 31.9 million at P150). The growth of the CCA paralleled the increase of myelinated axons (0.5% at P26 and 29.6% at P150 and in the mean axon diameters (0.34 micron at P39 and 0.42 micron at P150). A number of axonal ultrastructural peculiarities (electron-dense bodies, large vacuoles, lamellated bodies, etc., including those mentioned below) were noticed; their frequency at different ages was estimated as the percent of total axons. Interestingly, accumulations of vesicles inside axons increased from 4.1% at E53 to 8.9% at P26, dropped to 0.2% at P39, and remained below 1% thereafter. Swollen mitochondria increased from 0.2% at E53 to 0.9% at P26 and dropped to 0.06% (on the average) from P39 onward. Accumulations of vesicles and swollen mitochondria increased during the phase of rapid axonal elimination; thus, they may indicate axonal retraction and/or degeneration. Microglia-gitter cells and astrocytes showing signs of phagocytosis were found during the embryonic and early postnatal development and may be involved in axon elimination.     

Localization of zinc in the outer retina of carp: a light- and electron-microscopic study

Many lines of evidence suggest that zinc may play an important neuromodulatory role in the central nervous system, including the retina. In this work, localization of zinc in the outer retina of carp was studied, using the silver amplification method, by light and electron microscopy. Reaction products (silver grains) were widely distributed throughout the retina, including photoreceptors, the outer and inner nuclear layers (ONL and INL), the ganglion cell layer (GCL), as well as in both outer and inner plexiform layers (OPL and IPL). Generally, staining for zinc was stronger in the outer retina than in the inner retina, and grains were aggregated with the greatest density in the OPL and the outer limiting membrane (OLM). Silver precipitates were also detected in the inner segments, axons, but not outer segments of photoreceptors. At the ultrastructural level, zinc was localized to myoid regions, mitochondria in the inner segments, internuclear space and nuclei of photoreceptors. In addition, silver grains were found in the terminals of photoreceptors, cone pedicles, and rod spherules, as well as in some processes in the OPL, which might be dendrites of horizontal cells. The presence of zinc in the terminals of photoreceptors suggests that zinc might be released from photoreceptor terminals and play modulatory roles in the outer retina.     

Alexander's disease: Further light-, and electron-microscopic observations

Summary The neuropathologic and ophthalmopathologic findings in a 5^3/4-year-old boy with Alexander's disease are reported. Light- and electron-microscopic and immunohistochemical studies revealed that (1) the granular osmiophilic deposits (GOD) in Alexander's disease accumulate mainly in astrocytic processes to form Rosenthal fibers, (2) the Bergmann glia are different in this regard and accumulate the deposits primarily in their perikarya, (3) the Müller cells of retina (which closely resemble astrocytes) do not accumulate GOD, (4) the deposits are also not present in other glial cells and glial-like cells such as pituicytes and pineocytes, (5) the deposits are sparse in the retrobulbar optic nerves, and (6) the peroxidase-antiperoxidase and immunofluorescence studies did not demonstrate glial fibrillary acidic protein (GFAP), albumin, immunoglobulins, or fibrinogen in the astrocytic deposits.The differential deposition of GOD in various cytoplasmic regions of astrocytes in different areas of central nervous system (CNS) suggests that astrocyte metabolism may not be uniform throughout the brain. Attention to this point may prove helpful in understanding the pathogenesis of the deposits in Alexander's disease. The absence of immunohistochemically demonstrable plasma proteins and GFAP in the astrocytic GOD indicates that the latter have an origin different from plasma proteins and glial filaments. Alternatively, the deposits may be derived from these proteins, but their antigenicity has since been altered.     

The cortical form of subacute necrotizing encephalopathy of the Leigh type. A light- and electron-microscopic study.

The present paper is a clinico-pathological study of a 14-year-old boy with a chronic, progressive occipital syndrome for which he was operated upon. Postoperatively, metabolic acidosis developed. Pathological anatomy revealed spongy necrosis of the thalamus and corpora quadrigemina with the typical histological features of Leigh's necrotizing encephalopathy. Similar necrotic lesions had developed in the occipital cortex. At this level apart from the typical foci, cavitating necrosis was found as well as involvement of the smaller vessels of the pial circulation. Electron microscopy revealed vascular and glial changes suggestive of primary mesenchymoglial dystrophy. The histiocytes presented intracytoplasmic multiplication of lysosomes and their transformation into lipofuscin pigment. The changes demonstrate a juvenile cortical form of Leigh's subacute necrotizing encephalopathy.     

Toxic polyneuropathies in Italy due to leather cement poisoning in shoe industries. A light- and electron-microscopic study.

The peripheral nerve biopsy specimens of 4 cases of toxic polyneruopathies induced by exposure to leather cement in shoe industries were studied. Analysis of the cements used in the manufacturing process proved them to contain n-hexane as a volatile substance. Light- and electron-microscopic examination of nerve biopsies showed segmental swelling of axons due to the accumulation of packed filaments and thinning of the overlying myelin sheath. Neither active nerve fibre degeneration nor regeneration were frequently seen. It has been suggested that features of so-called giant axonal neuropathy are the most common pattern of peripheral nerve degeneration in chronic n-hexane intoxication.     

The myopathology of the Kocher-Debré-Sémélaigne syndrome: Electromyography,light- and electron-microscopic study

Clinical features as well as light and electron microscopy of muscle are described in 7 children with the Kocher-Debré-Sémélaigne syndrome (KDS) and in 3 children with cretinism but no muscular hypertrophy. Electromyography revealed a myopathic pattern in all 6 tested children with the KDS and was normal in the 1 tested child with cretinism and no muscle hypertrophy. Conventional light microscopy revealed central nucleation, variation in muscle fibre size and shape and abortive spiral annulets. No abnormalities were seen at this level of resolution in the 3 cretins with no clinical evidence of muscular hypertrophy. High resolution light microscopy and electron microscopy revealed abnormalities in muscle of KDS children as well as those without muscular hypertrophy. Electron-microscopic alterations included glycogen and mitocondrial aggregates, dilated sarcoplasmic reticulum profiles, honeycomb configurations of membrane profiles, ringbinden, Z-line irregularities as well as varying degrees of myofilamentous loss and disarray. Neuromuscular junctions were normal. Our findings are contrasted with those in the literature. Experimental evidence, possibly relating some of the observed alterations to the hypothyroid state, are cited from the literature. It is concluded that the myopathology of KDS is variable and nonspecific and that pathological alterations do occur in muscles of cretins without concomitant clinical muscular hypertrophy.     

Wheat germ agglutinin-apoHRP gold: a new retrograde tracer for light- and electron-microscopic single- and double-label studies

In this report, we describe a new colloidal-gold-labelled retrograde tracer, wheat germ agglutinin (WGA) conjugated to enzymatically inactive horseradish peroxidase (apoHRP). This protein gold complex (WGAapoHRP-Au) is a sensitive marker for retrograde tracing of the projections of CNS neurons at the light-microscopic (LM) level when a silver-enhancement procedure is used to detect the gold in the tracer. For electron-microscopic (EM) analysis, the silver-enhanced sections undergo a further gold-toning step. This protects against rapid oxidation and dissolution of the silver precipitate during the osmication procedure. A major advantage of WGAapoHRP-Au is that it can be used in a variety of multiple-labelling studies. When the retrograde transport of the new tracer is combined with that of the fluorescent dye, True Blue, neurons that have bifurcating axons can be readily demonstrated. Simultaneous immunofluorescent detection of the cytochemistry of the double-retrogradely labelled neurons is also possible. In contrast to a WGA-HRP gold complex, the new complex has no enzymatic activity. Thus HRP-based techniques (e.g., anterograde transport of WGA-HRP or peroxidase-antiperoxidase immunocytochemistry) can be performed on tissue that contains retrogradely labelled neurons marked with WGAapoHRP-Au without having to pretreat tissue so as to destroy endogenous HRP enzyme activity. At the EM level, the gold is readily distinguished from DAB immunoreaction product. This makes both LM and EM double-labelling studies possible. The great sensitivity of the new tracer, its compatibility with a variety of aldehyde fixatives, its ease of detection, and the fact that it can be simultaneously used with several fluorescent and HRP-based immunocytochemical and tracing techniques make WGAapoHRP-Au a valuable tool for LM and EM characterization of CNS cytochemistry and connectivity.     

Phrenic motoneurons receive monosynaptic inputs from the Kölliker–Fuse nucleus: a light- and electron-microscopic study in the rat

The parabrachial complex, which plays an important role in respiratory regulation, has been reported to send projection fibers to the phrenic nucleus, but the synaptic organization between the parabrachial fibers and the phrenic motoneurons has not been examined. Using anterograde and retrograde tracing methods, we found in the rat that the parabrachial fibers originating mainly from the Kölliker–Fuse nucleus (KF) terminated not only within the phrenic nucleus but also on the radial dendritic bundles of the phrenic motoneurons. It was further revealed that the KF fibers made asymmetrical synapses predominantly with dendrites and partly with somata of the phrenic motoneurons. These data suggest that output signals from the KF may exert excitatory influence directly upon the phrenic motoneurons.     

A case of cerebellar ganglioglioma in an infant--immunohistochemical study

Ganglioglioma is a rare brain tumor which occurs in an infant and young adult. The term "ganglioglioma" was originally proposed by Ewing in 1926 and subsequently adopted by Courville in 1930. Histogenesis of ganglioglioma is still speculative, but the hypothesis that ganglioglioma is derived from hamartomatous sympathetic neurons is generally thought to be probable. Gangliogliomas of the brain arise frequently from the temporal lobe, frontal lobe, cerebellum and spinal cord. Its growth is gradual and clinically it is a benign tumor, but its malignant transformation has been reported. Ganglioglioma is a tumor composed of both neuronal and glial cells, but the ratio of these two-cell components varies a great deal from case to case and in different areas even of the same tumor. The authors experienced a cerebellar ganglioglioma in an infant which was successfully removed. Histopathological and immunohistochemical studies of the biopsy specimen have been done. That is, histopathological staining with H-E (hematoxylin eosin), PTAH (phosphotangustic acid hematoxylin), cresyl-violet and Bodian, and electron microscopical studies were performed. Also the authors immunohistochemically examined the presence or absence of GFAP (glial fibrillary acidic protein), NSE (neuron specific enolase), S-100 alpha and beta subunits. Histopathologically, the authors could find nerve fiber, glial fiber and identify neuronal cells which had Nisslgranules in the cytoplasm. Electron microscopically the authors could distinguish the neuronal cells which had large nuclei and prominant nucleoli from the glial cells which had processes filled with intermediate glial filaments.(ABSTRACT TRUNCATED AT 250 WORDS)     

Neuronal organization of fetal striatal grafts in kainate- and sham-lesioned rat caudate nucleus: light- and electron-microscopic observations

Behavioral and biochemical studies have suggested that fetal striatal grafts in the adult rat neostriatum can reverse deficits induced by excitotoxic lesions of the host caudate tissue. In this study, fetal day 17-18 striatal grafts were examined at 2, 5-6, 12, and 44-48 weeks following their implantation into saline- or kainic acid-treated host caudate nucleus in order to compare the neuronal organization of the grafts and the host caudate nucleus and to determine whether the differentiation of graft tissue was influenced by the period of implantation or prior lesion of the host caudate nucleus with kainic acid. Compared to host neostriatum, the grafts at the light-microscopic level lacked bundles of myelinated axons and had neurons that were tightly packed in clusters and rich in Nissl substance. Neurons in the grafts were mostly of medium size, had significantly larger cross-sectional areas, and more frequently exhibited indented nuclei than host caudate neurons. At the electron-microscopic level, grafts 2 weeks following implantation contained many features seen in the normally developing neostriatum, such as growth cones, immature synapses, and degenerating profiles. Grafts appeared mature by 5-6 weeks and contained at least 6 types of neurons and 8 types of axon terminals, which formed synapses with cell bodies, dendrites, spines, and axon initial segments. Both symmetric and asymmetric synapses were found within the grafts. The density of synapses was significantly lower in all the transplants than in host tissue, with the exception of the 5-6 week grafts, where values were statistically comparable to host caudate. A significantly higher proportion of axodendritic synapses was present in the graft neuropil than in the caudate nucleus. The lengths of the synaptic junctions in the grafts were the same as those in the neostriatum. There was little qualitative or quantitative difference in synaptic organization between transplants in kainic acid and sham-lesioned host, with grafts in both host treatment conditions exhibiting the same synaptic density and proportion of axodendritic/axospinous synapses. The development of a high differentiated ultrastructure within striatal grafts is consistent with recent anatomical evidence showing interconnections between striatal grafts and host-lesioned caudate nucleus. Although graft neuropil shows striking similarities in neuronal organization to the caudate nucleus, it also exhibits some distinct differences that may have implications for understanding the functional properties of fetal striatal grafts in animal models of Huntington's disease.     

A Golgi and electron-microscopic study of cerebellum in methylmercury-poisoned neonatal mice

Summary Neonatal C57BL/6J mice were injected with 5 mg/kg body weight of²⁰³Hg-labeled methylmercuric chloride on postnatal days 3, 4, and 5, totaling 15 mg/kg body weight per animal. The experimental and control animals were sacrificed on postnatal day 15. Whole body radioactivity of²⁰³Hg progressively increased during the 3-day injection period and reached the peak level and remained at peak levels until the time of sacrifice. This indicates a lack of clearance of²⁰³Hg by neonatal mice during the period examined in this study. Golgi preparations of cerebella of MeHg-treated animals revealed significant reduction in dendritic arborization of Purkinje cells. Ultrastructurally, the vascular endothelium showed attenuation with increased electron density and frequent vacuolization of cytoplasm. Marked swelling of perivascular glia was noted in most of the capillaries throughout the cerebella of MeHg-treated animals.This study is supported in parts by USPHS NIEHS Grants 5R01-ES 01722 and ES 01247     

高渗刺激后大鼠视上核星形胶质细胞和神经元的反应及其相互关系的光、电镜研究

目的探讨大鼠尾静脉注射高渗盐水(9％NaCl，5．5mL／kg)后，视上核(SON)内星形胶质细胞和神经元的可塑性反应及相互间的关系。方法用免疫组织化学和免疫电镜技术，观察刺激后15，45，90，180和360minSON内缝隙连接蛋白43(Cx43)和蛋白32(Cx32)的变化及超微结构。结果光镜下观察到Cx43阳性星形胶质细胞在15min出现，45min达到高峰；Cx32阳性神经元90min达到高峰。电镜下在SON内，观察到下列四种超微结构：(1)突触样结构(synapse like structure)，位于神经元的轴突末梢与Cx43阳性的星形胶质细胞突起之间；(2)三成分的突触复合体(tripartite synaptic structure)，由突触前膜、突触后膜和靠近此突触的星形胶质细胞突起共同组成；(3)同源性缝隙连接(gap junction，GJ)，位于星形胶质细胞突起之间，两侧均为Cx43；(4)“异源性缝隙连接样结构”(heterotypic gap junctions，HGJ)，是由Cx32阳性神经元和Cx43阳性星形胶质细胞突起组成的一种超微结构。结论高渗刺激后，SON内Cx43阳性星形胶质细胞和Cx32阳性神经元明显增加，前者出现和高峰的时间早于神经元；两者之间的HGJ数量明显增加，其他结构的数量变化不明显，因此两者可能是通过HGJ进行快速的信息交流。     

Glycine-immunoreactive terminals in the rat trigeminal motor nucleus: light- and electron-microscopic analysis of their relationships with motoneurones and with GABA-immunoreactive terminals

Post-embedding immunolabelling methods were applied to semi-thin and ultrathin resin sections to examine the relationships between glycine- and γ-aminobutyric acid (GABA)-immunoreactive terminals on trigeminal motoneurones, which were identified by the retrograde transport of horseradish peroxidase injected into the jaw-closer muscles. Serial sections were cut through boutons and alternate sections were incubated with antibodies to glycine and GABA. Light-microscopic analysis of semi-thin sections revealed a similar pattern of glycine and GABA-immunoreactive boutons along the motoneurone soma and proximal dendrites, and of immunoreactive cell bodies in the parvocellular reticular and peritrigeminal areas surrounding the motor nucleus. Immunoreactive synaptic terminals on motoneurones were identified on serial ultrathin sections at electron-microscopic level using a quantitative immunogold method. Three populations of immunolabelled boutons were recognized: boutons immunoreactive for glycine alone (32%), boutons immunoreactive for GABA alone (22%), and boutons showing co-existence of glycine and GABA immunoreactivities (46%). Terminals which were immunoreactive for glycine only contained a higher proportion of flattened synaptic vesicles than those which were immunoreactive for GABA only, which contained predominantly spherical vesicles. Terminals which exhibited both immunoreactivities contained a mixture of vesicle types. All three classes of terminal formed axo-dendritic and axo-somatic contacts onto retrogradely labelled motoneurones. A relatively high proportion (25%) of boutons that were immunoreactive for both transmitters formed synapses on somatic spines. However, only GABA-immunoreactive boutons formed the presynaptic elements at axo-axonic contacts: none of these were found to contain glycine immunoreactivity. These data provide ultrastructural evidence for the role of glycine and GABA as inhibitory neurotransmitters at synapses onto jaw-closer motoneurones, but suggest that presynaptic control of transmission at excitatory (glutamatergic) synapses on motoneurones involves GABAergic, but not glycinergic inhibition.