Ultrastructure of the central nervous system after prolonged hypoxia. I. Neuronal alterations

CTCF loss induces giant lamellar bodies in Purkinje cell dendrites

CCCTC-binding factor (CTCF) has a key role in higher-order chromatin architecture that is important for establishing and maintaining cell identity by controlling gene expression. In the mature cerebellum, CTCF is highly expressed in Purkinje cells (PCs) as compared with other cerebellar neurons. The cerebellum plays an important role in motor function by regulating PCs, which are the sole output neurons, and defects in PCs cause motor dysfunction. However, the role of CTCF in PCs has not yet been explored. Here we found that the absence of CTCF in mouse PCs led to progressive motor dysfunction and abnormal dendritic morphology in those cells, which included dendritic self-avoidance defects and a proximal shift in the climbing fibre innervation territory on PC dendrites. Furthermore, we found the peculiar lamellar structures known as "giant lamellar bodies" (GLBs), which have been reported in PCs of patients with Werdnig-Hoffman disease, 13q deletion syndrome, and Krabbe disease. GLBs are localized to PC dendrites and are assumed to be associated with neurodegeneration. They have been noted, however, only in case reports following autopsy, and reports of their existence have been very limited. Here we show that GLBs were reproducibly formed in PC dendrites of a mouse model in which CTCF was deleted. GLBs were not noted in PC dendrites at infancy but instead developed over time. In conjunction with GLB development in PC dendrites, the endoplasmic reticulum was almost absent around the nuclei, the mitochondria were markedly swollen and their cristae had decreased drastically, and almost all PCs eventually disappeared as severe motor deficits manifested. Our results revealed the important role of CTCF during normal development and in maintaining PCs and provide new insights into the molecular mechanism of GLB formation during neurodegenerative disease.

Moderate loss of cerebellar Purkinje cells after chronic bilateral common carotid artery occlusion in rats

Pathological effects of moderate ischemia (oligemia, hypoperfusion) are relevant in relation to vascular factors in dementia. Chronic bilateral common carotid artery occlusion (BCCAO) in adult Wistar rats induces oligemia and leads to acute changes in gene expression, subacute changes in cortical astrocytes and prolonged changes in white matter tracts, while largely sparing neurons in the forebrain areas. Dilation and remodeling of the basilar artery ensures blood flow to the forebrain. The present study examined the hypoxia-sensitive Purkinje cells in the cerebellum after 6 months of BCCAO using conventional neuropathological analysis, immunohistochemistry and high-precision design-based stereologic methods. Purkinje cells in the vermis region revealed abnormally shaped nuclei. A stereologic analysis showed that the mean total number of Purkinje cells within the vermis was statistically significantly smaller in the BCCAO animals than in the control animals (d = 11.8%; P < 0.0001). BCCAO had no significant effect on the mean volumes of the molecular layer, granule cell layer and white matter in the vermis or the entire cerebellum. Remodeling of the basilar artery indicated that secondary vascular perturbations might be responsible for the effects of BCCAO on the cerebellar Purkinje cells.

Methylmercury-induced astrocytic swelling is associated with activation of the Na+/H+ antiporter, and is fully reversed by amiloride

Astrocytes are a known 'sink' for brain methylmercury (MeHg) deposition. Yet, the significance of the preferential accumulation of MeHg within these cells is imprecisely defined. To determine whether MeHg in isotonic buffer has the potential to interfere with homeostatic functions, we measured its effect on astrocytic volume using an electrical impedance method [E.R. O'Connor, H.K. Kimelberg, C.R. Keese, I. Giaever, Electrical impedance method for measuring volume changes in astrocytes, Am. J. Physiol. 264 (1993) C471-C478.]. In addition, we have characterized the alterations in astrocytic ion permeability associated with exposure to this organometal. The results show that MeHg rapidly induces astrocytic swelling, and that this effect is secondary to increased astrocytic Na+ uptake. Furthermore, the effect of MeHg on astrocytic swelling is completely inhibited by amiloride, but not by SITS (4-acetamido-4'-isothiocyanatostilbene-2,2'-disulfonic acid), furosemide, or bumetanide. Accordingly, increased cellular permeability to Na+ via the Na+/H+ antiporter is invoked as the primary mechanism of MeHg-induced astrocytic swelling.

Ion homeostasis in brain cells: differences in intracellular ion responses to energy limitation between cultured neurons and glial cells

Intracellular concentrations of sodium, potassium and calcium together with membrane potentials were measured in cultured murine cortical neurons and glial cells under conditions which mimicked in vivo hypoxia, ischemia and hypoglycemia. These included; glucose omission with and without added pyruvate, addition of rotenone in the presence and absence of glucose and substitution of 2-deoxyglucose for glucose with and without rotenone. Cellular energy levels ([ATP], [ADP], [phosphocreatine], [creatine]) were measured in suspensions of C6 cells incubated in parallel under identical conditions. [Na+]i and [Ca2+]i rose while [K+]i fell and plasma membrane depolarized when energy production was limited. Intracellular acidification was observed when glycolysis was the sole source for ATP synthesis. There was a positive correlation between the extent of energy depletion in glial cells and the magnitude and velocity of alterations in ion levels. Neither glycolysis alone nor oxidative phosphorylation alone were able to ensure unaltered ion gradients. Since oxidative phosphorylation is much more efficient in generating ATP than glycolysis, this finding suggests a specific requirement of the Na pump for ATP generated by glycolysis. Changes in [Na+]i and [K+]i observed during energy depletion were gradual and progressive whereas those in [Ca2+]i were initially slow and moderate with large elevations occurring only as a late event. Increases in [Na+]i were usually smaller than reductions in [K+]i, particularly in the glia, suggestive of cellular swelling. Glia were less sensitive to identical insults than were neurons under all conditions. Results presented in this study lead to the conclusion that the response to energy deprivation of the two main types of brain cells, neurons and astrocytes, is a complex function of their capacity to produce ATP and the activities of various pathways which are involved in ion homeostasis.

Altered axon terminals containing concentric lamellar bodies of cerebellar Purkinje cells in Mongolian gerbil

Altered axon terminals containing concentric lamellar bodies were observed in cerebellar and vestibular nuclei of the Mongolian gerbil. The terminals increased in number from 30 days of age onward, and reached about tenfold at 360 days. The numbers were the same in two gerbil strains with different susceptibility to spontaneous motor seizures by various stimuli, but about threefold those in Slc:Wistar rat.

Krabbe's disease with giant lamellar bodies in Purkinje cells

An autopsy case of Krabbe's disease in a child aged 6 years 7 months 1s reported. Histologically, globoid cells, loss of myelin, oligodendroglia and axons, and marked gliosis were observed in the white matter. In addition, there was severe neuronal loss in the thalamus, pontine nucleus, dentate nucleus and olivary nuclei. The cerebellar cortex showed extensive loss of granular cells and moderate loss of Purkinje cells. There were numerous eosinophilic inclusion bodies, ranging from 2 to 15 microns in diameter, in the dendrites of Purkinje cells. The ultrastructural findings for the inclusion bodies were consistent with those of giant lamellar bodies. In addition, smaller lamellar bodies were frequently observed in the perikarya and dendrites. Although loss of granular cells was more prominent in the hemispheres than in the vermis, the inclusion bodies were observed in hemispheres but were infrequently observed in the vermis. They were found in degenerated Purkinje cells which had lost afferent fibers. It is considered that these giant lamellar body inclusions are an unusual type of degenerative structure specific to Purkinje cells.

Inositol 1,4,5-trisphosphate receptor causes formation of ER cisternal stacks in transfected fibroblasts and in cerebellar Purkinje cells

The inositol 1,4,5-trisphosphate receptor (IP3R) is expressed at very high levels in cerebellar Purkinje cells. Within these neurons, it has a widespread distribution throughout the endoplasmic reticulum (ER) and is present at particularly high concentrations at sites of membrane appositions within peculiar stacks of ER cisternae. Here we report that stacks of ER cisternae, reminiscent of those observed in Purkinje cells, can be induced by overexpression of full-length IP3R, but not of mutant forms of the protein in COS cells. Within these stacks the IP3R forms a crystalline array at apposed cisternal faces. Additionally, we show that Purkinje cell stacks are not permanent structures. Our findings suggest that massive stack formation in purkinje cells represents an adaptive response of the ER to hypoxic conditions and is due to the presence of the high concentration of IP3R in its membranes.

A role of GABAA receptors in hypoxia-induced conduction failure of neonatal rat spinal dorsal column axons

GABA (gamma-aminobutyric acid) depresses axonal conduction in neonatal dorsal columns. GABA released by injured spinal neurons may diffuse to white matter and contribute to secondary axonal damage. We studied the effects of hypoxia and GABAA receptor blockade on dorsal column conduction in vitro. The experiments compared the effects of hypoxia on longitudinally hemisected spinal cords and isolated neonatal dorsal columns. Before hypoxia, electrical stimulation elicited robust conducted compound action potentials in both isolated dorsal columns and hemicords. The tissues were superfused for 120 min with a hypoxic Ringer's solution saturated with 95% N2 and 5% CO2, followed by oxygenated Ringer's solution for 90 min. Isolated dorsal columns were remarkably insensitive to hypoxia. Response amplitudes fell by only 11 +/- 7% (n = 5) during hypoxia. In hemicords, however, hypoxia reduced response amplitudes by 56 +/- 16% (n = 5, mean +/- S.E.M.) and re-oxygenation did not restore response amplitude. We applied bicucullin (10(-5) M) to block GABAA receptors in the hemicords during hypoxia. Response amplitudes in bicucullin-treated hemicords fell by only 3 +/- 9% (n = 5) during hypoxia but declined 31 +/- 5% during re-oxygenation. These results suggest that endogenous GABA released from gray matter contributes to hypoxia-induced dorsal-column conduction failure.

Membranous cytoplasmic bodies in the lateral wall of the cat cochlea

Membranous cytoplasmic bodies (MCBs) were observed both in the intermediate cells of the stria vascularis and in the fibrocytes of the spiral ligament in normal cats. The MCBs in the intermediate cells were round or ovoid, ranged from 1 to 5 microns in diameter, and consisted of 2 to 40 or more layers disposed concentrically about a core. The core was composed of not only cytoplasm but also of mitochondria in various stages of disintegration, empty vacuoles, and many kinds of dense bodies similar to lysosomes. The MCBs in the fibrocytes were similar to those in the intermediate cells, but they were a little smaller in diameter and consisted of fewer than 10 layers. Both in the intermediate cells and in the fibrocytes, MCBs seem to have a phagocytic function.

Brain changes in experimental chronic hypoxia

A model of normobaric hypoxia was developed in which adult female cats were exposed to decreasing amounts of oxygen (21, 15, 10, 8, 7, and 5 vol.%) over a period of 320 days. Blood flow as well as the blood flow responses to changes of pCO2 were depressed in both cerebrum and cerebellum. These decreases were more severe in the cerebellum. The metabolic rate for oxygen was also depressed. A decrease in the Purkinje cell number was evident. A different degree of damage was observed in the top, the intermediate and the bottom region of the cerebellar gyri. Microvascular proliferation occurred in the whole brain.

Altered glial fibrillary acidic protein immunoreactivity in rat brain following chronic hypoxia

Glial fibrillary acidic immunoreactivity in brain was examined in normal animals and in rats subjected to chronic hypoxia. Animals were exposed to a chronic normobaric adaptive hypoxia with decreasing amounts of oxygen (finally 6%) for a period of 59 and 114 days, respectively. In paraffin-embedded sections the glial fibrillary acidic protein immunoreactivity in normal and hypoxic animals was examined at three coronal levels. A mild glial fibrillary acidic protein immunoreactivity in the perivascular glial layer, external glial limitans membrane and periventricular astrocytes, as well as in some areas of hippocampus and cerebellum, was noted in normal animals. Chronic hypoxia for 114 days resulted in a marked increase of glial fibrillary acidic protein immunoreactivity in dentate gyrus of hippocampus, Bergmann glia of the cerebellum, internal capsule and pyramidal tract. On the other hand, the glial fibrillary acidic protein activity following 59 days hypoxic exposure was almost the same as controls. These results show that systemic deep chronic hypoxia (depending on the intensity and the duration) activates the endogenous expression of glial fibrillary acidic protein in astrocytes of specific brain regions. The probable significance of this finding is discussed.

Cerebellar degeneration induced by acetyl-ethyl-tetramethyl-tetralin(AETT)

The neurotoxicity of acetyl-ethyl-tetramethyl-tetralin (AETT) was investigated following its percutaneous administration to rats. Animals exposed to a high-dose of AETT developed a gait abnormality that progressed to severe ataxia. Microscopic examinations revealed remarkable cerebellar changes in addition to a widespread accumulation of ceroid-like pigmentation in the neuronal cytoplasm. The cerebellar changes, especially in the vermis and intermediate part, were characterized by selective degeneration and depopulation of Purkinje cells, and a spongy state of the cerebellar white matter, which was formed in splits in the intraperiod lines within the myelin sheath. In contrast, there were only negligible changes of granule cells and other neuronal elements. Accumulation of ceroid-like pigments and selective damage to the Purkinje cells seen in the present study together provide a basis for understanding the pathogenesis of AETT intoxication and distinguish it from other experimentally induced conditions. Thus, high-dosage AETT intoxicated rats may constitute a new experimental model of cerebellar degeneration.

Astrocytic swelling in traumatic-hypoxic brain injury. Beneficial effects of an inhibitor of anion exchange transport and glutamate uptake in glial cells

Swelling of brain slices is shown to occur in response to elevated potassium levels or glutamate, which is accompanied by astrocytic swelling. Cl-/HCO3- anion exchange inhibitors, such as SITS (4-acetamido-4'-isothiocyanostilbene-2,2'-disulfonic acid) or furosemide, but not the specific cotransport inhibitor bumetanide, inhibit swelling or increased ion uptake in rat brain slices caused by elevated potassium although there were marked species differences in sensitivity. A novel anion exchange inhibitor, L-644,711, inhibits swelling and increased ion uptake caused by glutamate in rat and cat brain slices, as well as inhibiting [3H]glutamate uptake in primary rat astrocyte cultures. Possible mechanisms of action of the inhibitors are discussed. L-644,711 was also found to be effective in promoting recovery from a trauma plus hypoxia head injury model in cats. Marked perivascular astrocytic swelling is associated with this head injury model, and L-644,711 also inhibited such astroglial swelling as determined ultrastructurally. The significance of these findings in relation to possible connections between astrocytic swelling and brain pathology is discussed.

Lactic acid-induced swelling in C6 glial cells via Na+/H+ exchange

One of the primary consequences of ischemia is tissue acidification due to anaerobic production of lactic acid. Upon reperfusion and recovery of pH, cytotoxic edema often ensues. Na+/H+ exchange, a mechanism involved in the regulation of intracellular pH (pHi), is activated by low intracellular pH, is dependent on extracellular Na+, and is inhibited by low extracellular pH (pH less than 6) or by amiloride. In this study we explore the role of Na+/H+ exchange in cell swelling following cytoplasmic acidification of C6 glioma cells. Postischemic intracellular acidification was simulated in vitro by exposure of cells in suspension to: (1) 20 or 140 mM lactic acid; or (2) 10 microM oligomycin. pHi was monitored fluorimetrically using the intracellularly trapped pH-sensitive dye bis(carboxyethyl)carboxyfluorescein. Cell volume was measured electronically with a Coulter Counter/Channelyzer. Both simulations of ischemia caused intracellular acidification followed by recovery. pHi recovery was mediated by Na+/H+ exchange, since it was amiloride-sensitive and Na+-dependent. This pHi reversal following lactic acid-induced acidification was also inhibited at pHo less than 6. Volume measurements showed that cells suspended in 140 mM Na-lactate/lactic acid swelled by 19% over 15 min. This swelling was Na+-dependent, and inhibited by amiloride and pHo less than 6. These results suggest that Na+/H+ exchange may be involved in cell swelling following cytoplasmic acidification, and thus may be involved in postischemic cytotoxic brain edema.

"Grumose degeneration" of the dentate nucleus. A light and electron microscopic study in progressive supranuclear palsy and dentatorubropallidoluysial atrophy

So-called "grumose degeneration" (GD) of the dentate nucleus (DN) which is a unique alteration in progressive supranuclear palsy and dentatorubropallidoluysial atrophy was studied by light and electron microscope. Light microscopically, the presence of a large amount of eosinophilic granular and/or amorphous material around the neurons is the most conspicuous feature of GD. In addition, the number of neurons is decreased and some of them are swollen as with central chromatolysis. Electron microscopically, the granular and/or amorphous material mainly consists of the altered axon terminals of the Purkinje cells (Pax), which are relatively electron-dense and characteristically contain varying numbers of deformed lamellar bodies, highly electron-dense mitochondria and many vacuoles which are adherent to the astrocytic processes. GD is a unique histological change of both the chromatolytic DN neurons and the grumose appearance of the altered Pax. Possible mechanisms are discussed.

Histopathological changes induced by disturbance of microcirculation in the rat brain

Microcirculatory disturbance was induced in 8 rats after injecting microsphere latex (5 micron in diameter) from the right carotid artery. Ultrastructural observations revealed that initial changes occurred in the vascular feet of astroglial cells and the subsequent swelling of postsynapses. Succeedingly presynapses and nerve cells also became atrophic but this was considered to be caused by astrocytic degeneration. From these findings, it is speculated that the neuronal atrophy was secondary to the changes in the neuropil around the capillary caused by disturbance of the nutritional supply from the blood induced by microcirculatory disturbance. The above described findings seemed to have some similarity to those of nonspecific degeneration of the cortex observed in the brain, such as Alzheimer's disease.

A study of cerebellar and cerebral cortical degeneration in miniature poodle pups with emphasis on the ultrastructure of Purkinje cell changes

In a litter of three Miniature Poodles, a normal female pup contrasted with two males which displayed severe equilibrium and postural disturbances soon after birth. In the male pups diffuse cerebral cortical degeneration accompanied cerebellar cortical atrophy, which was characterized by extensive loss and degeneration of Purkinje neurons. As in some prior histological descriptions of canine cerebellar atrophies, degenerating Purkinje cells appeared either pale, swollen and vacuolated or shrunken and hyperchromatic. Swollen vacuolated cell bodies and condensed necrotic neurons were scattered through the cerebral cortex. Ultrastructural studies revealed that the vacuolar degeneration in Purkinje and cerebral neurons was referable to marked dilation of endoplasmic reticulum and loss of ribosomes. In shrunken Purkinje neurons, increased cytoplasmic eosinophilia was associated with a decline in Nissl bodies and accumulations of mitochondria and especially lamellar bodies. The latter, stacked derivatives of endoplasmic reticulum, were not encountered in shrunken cerebral perikarya. Lamellar bodies reached giant proportions in the dendritic stems of degenerating Purkinje neurons. In Purkinje axons, however, these bodies often were overshadowed by aggregates of axoplasmic tubules. The cytological changes in these Poodle pups were notably different from those reported in earlier ultrastructural studies of canine inherited cerebellar degenerations.

Neuronal changes induced by neonatal hypothyroidism: an ultrastructural study

The postnatal development of the neurons of the cuneate nucleus was examined ultrastructurally in euthyroid and hypothyroid rats from birth to the sixth postnatal week. In the euthyroid animals, the neurons at birth displayed mild nuclear invaginations and a scanty cytoplasm with few organelles. By 2 weeks, there was a considerable increase in Nissl bodies. At 3 weeks, the neurons contained short lamellar arrays of endoplasmic reticulum. Between 3 and 6 weeks there was a reduction in the Nissl substance. In the hypothyroid animals, although the sequence of maturational changes generally resembled that of the controls, a number of differences were noted. The neurons at 1 week displayed dilations of perinuclear space, rough endoplasmic reticulum, Golgi complexes, and mitochondria. At 4 weeks both perikaryon and myelinated axons contained glycogen. Several neurons with cytoplasmic inclusions considered to be nonfunctional RNA were seen. The 6-week hypothyroid neuron exhibited large, clear, cytoplasmic vacuoles associated with a drastic reduction in cytoplasmic organelles. Presynaptic terminals showed a 50% reduction in mitochondrial numbers associated with the presence of glycogen granules. Three changes observed in neurites in all the age groups included: (1) large accumulation of glycogen in presynaptic terminals; (2) clear vacuoles; and (3) the presence of numerous lamellar bodies within reactive axons. Aberrant myelination, such as a single myelin sheath enclosing multiple processes, and instances of collapsed and redundant myelin were encountered.

Complete cerebral ischaemia in the rat: an ultrastructural and stereological analysis of the distal stratum radiatum in the hippocampal CA-1 region

An ultrastructural study and a stereological analysis of the distal stratum radiatum in the hippocampal CA-1 region of the rat were performed after 10 min of complete cerebral ischaemia followed by 10, 20 and 60 min of blood reflow periods. Post-ischaemic changes were mainly limited to the region of synaptic terminals which showed either clumping or dispersion of the synaptic vesicle pools and damage to synaptic membranes. Presynaptic terminals and astrocytes were swollen after 10 and 20 min of reflow, but this abated after 60 min. Mitochondria in neurons showed varying degrees of swelling, but in astrocytes their structure was normal. There were no changes in capillaries. After 20 and 60 min of blood reflow, disruption of cell membranes was observed, mainly in the vicinity of the synaptic terminals. The size of the extracellular space diminished by approximately 30% in all three ischaemic groups. The data show that synaptic terminals are a primary and early target in the development of postischaemic nerve cell damage.

Effect of CDP-choline on the biosynthesis of phospholipids in brain regions during hypoxic treatment

Acute administration of CDP-choline (i.p. 100 mg/Kg b.w.), 10 min before the intraventricular injection of labeled precursors, [2-3H] glycerol and [1-14C]-palmitate, was able to correct the impairment caused by hypoxic treatment of lipid metabolism in some brain regions, ie, cerebral hemispheres, cerebellum, and brainstem. After CDP-choline treatment, an increase of the specific radioactivity of total lipids and of phospholipids was observed in mitochondria purified from the three above-mentioned brain regions of the hypoxic animals, while no effect on the other subcellular fractions was found. CDP-Choline had a stimulating effect particularly on the incorporation of both precursors into mitochondrial PC, PE, and polyglycerophosphatides isolated form the three brain regions examined. The results obtained show that the action of CDP-choline in restoring lipid metabolism was more pronounced in brain mitochondria, which, among subcellular fractions, were the most affected by the hypoxic treatment.

Effect of hypoxia on the incorporation of [2-3H] glycerol and [1-14C[-palmitate into lipids of various brain regions

The lipid metabolism in guinea pig brain after intermittent hypoxia, prolonged for 80 hrs, was markedly impaired. The in vivo incorporation of [2-3H] glycerol adn [1-14C] palmitate into lipids of microsomes, mitochondria, myelin, and synaptosomes, purified form cerebral hemispheres, was significantly lower in the hypoxic animals than in the controls. The same effect was observed on the incorporation of labeled precursors into lipids of mitochondria purified from cerebellum and brainstem. In particular, the labeling of th major phospholipids present - ie, phosphatidylcholine (PC) and phosphatidylethanolamine (PE) - in the mitochondria of the three brain regions examined decreased after hypoxic treatment.

The occurrence of cytoplasmic lamellar bodies in normal and pathologic conditions

Lamellar bodies are stacks of parallel cisternae of approximately regular spacing derived from ergastoplasm. Their occurrence was studied in various nervous and epithelial cells of different animal species in both normal and diseased subjects. This organelle appears to be, at least for some cell types, a normal cytoplasmic feature. The number of lamellar bodies increases in some pathologic conditions and when the cell metabolism is elevated.

Influence of hypoxia on the composition of isolated edema fluid in cold-induced brain edema

The isolation of edema fluid from cats with cold-induced cerebral edema allowed the study of changes of Na+ and K+ content, lactate dehydrogenase and creatine phosphokinase activity, colloid osmotic pressure and the level of intravenously administered 99mTc-albumin in the edema fluid during a period of hypoxia. The changes consisted of an increase of all mentioned parameters, except Na+; and could be interpreted as a concentration of solutes (but for Na+) in the extracellular edema fluid, concomitant to a reduction of the extracellular space, as the oxygen deficiency caused improper functioning of the cellular Na+-K+ pump, with a resulting shift of fluid (including Na+) into the cellular elements.

Electron microscopic studies of serially sectioned cat spinal alpha-motoneurons. I. Effects of microelectrode impalement and intracellular staining with the fluorescent dye "Procion Yellow"

Cat spinal alpha-motoneurons were studied in the light and electron microscope after intracellular recording and staining with the fluorescent dye Procion Yellow. Generally, the ultrastructural preservation of the stained neurons improved when the amount of dye delivered was decreased, and when the duration of the microelectrode impalement of the neuron as well as the time between the intracellular staining and the tissue fixation was kept as short as possible. Utilizing the optimal experimental procedure finally arrived at, about one-third of the stained neurons could be used for further quantitative morphometric analysis. With respect to synaptology and gross architecture these cells appeared to differ from control motoneurons mainly with regard to a focal disarrangement of the cell body periphery, probably a result of the microelectrode injury, and a certain degree of damage to some large boutons.

[Myelinopathy due to carbon monoxyde poisoning. A study in ultrastructural neuropathology (author's transl)]

A 24-year-old woman was found comatose after 2 days of cephalalgia and vomiting. An immediate diagnosis of carbon monoxyde poisoning was disclaimed when blood carbon monoxyde was found to be 1.75 ml/100. A diagnosis of acute intracranial hypertension led to trephination with ventricular punction and brain biopsy on the third day. The patient died on the eleventh day. Ultrastructural study of biopsy tissue showed nearly normal cortex, and injured white matter, with disrupted or destroyed myelin and pycnotic oligodendroglia in contrast with nearly normal axons, astrocytes, and capillaries. Autopsy showed a typical semioval center myelinopathy. After discussion of the histotoxic, vascular, and edema theories for myelinopathy pathogenesis, primary oligodendrogial lesion is considered, and correlated with the diphasic evolution often observed in the course of carbon monoxyde myelinopathy.

A quantitative histological study of changes in neurons and glia in the Gunn rat brain

The rostral part of the anterior limb of the anterior commissure (RAL) and the indusium griseum of the brains of Gunn rats and Wistar rats were examined quantitatively to assess the effects of hyperbilirubinaemia on the developing nervous system. The number of glia in the RAL was significantly less in Gunn rats than in the Wistar rats. The number of glia in the indusium griseum was similar in both groups but the Gunn rats showed a decrease of about 20% in the number of neutrons in this region. Myelination appeared to be unaffected and apart from an apparent increase in the number of dense bodies in astrocytes and oligodendrocytes there were no obvious morphological changes in either glia or neurons.

Experimental cerebral concussion. Part 1: An electron microscopic study

Cerebral concussion was produced in rats by an iron pendulum hitting the external occipital protuberance. This resulted in loss of consciousness lasting from 3 to 10 minutes with prompt recovery and no focal neurological signs. The energy absorbed by the head at the impact was calculated to be about 1450 gm/cm. Light microscopic survey showed only minor pathological changes. However, electron microscopic observation revealed considerable alteration which began at 30 minutes, reached a peak at 1 hour, and disappeared at 24 hours after concussion. The salient changes included severe swelling of the neuronal mitochondria at the point of impact (occipital cortex), and extracellular edema at the site of contre coup (frontal lobe). Topographically, the most severe alteration was seen in structures at the craniospinal junction (medulla oblongata and upper cervical cord), consisting of both mitochondrial and edematous changes. Although there was no visible opening of the capillary interendothelial junctions, extravasated ferritin particles were accumulated in the edematous regions, indicating a transient increase in the permeability of the blood-brain barrier.

Ultrastructural hypoxic changes in Ammon's horn and Purkinje cells

Guinea pigs were exposed for varying periods to different degrees of hypoxia by respiration of controlled mixtures of O2-N2 and the CNS subjected to both light and electron microscopic examination after aldehyde fixation by perfusion. The subacute anoxia experiments revealed an alteration in the rough endoplasmic reticulum of the Purkinje cells consisting of the formation of 'paired cisternae'. In the chronic anoxia experiments, small ultrastructural alterations of the same cells were found in association with the appearance of monoparticulate glycogen. The authors debate the significance of these ultrastructural alterations in relation to the damage found in other organs.

[Tumor- and drug-induced cutaneous axonal dystrophy. An electronmicrocopy proof of multiple lamellated bodies]

A marked cutaneous axonal dystrophy has been observed electronmicroscopically for the first time in the skin of three patients: (a) lesion of pityriasis lichenoides chronica in a patient with bronchogenic carcinoma, (b) non involved skin of a patient with malignant melanoma and (c) non involved skin of a patient with gout and retinal damage after prolonged use of chloroquine. The affected myelinated and non myelinated axons showed distinct alterations of mitochondria and multiple osmiophilic lamellated bodies (LK). These changes were interpreted as a (poly-)neuropathy, due to the influence of toxic systemic agents, such as malignant tumor and abuse of drugs. Chloroquine is known to induce neural damage. Moreover, some other compounds (ergotamine, ethaverine, analgetic preparations) may also be responsible for the drug-induced axonal dystrophy described in this study.