Oligodendroglial cell behaviour in traumatic oedematous human cerebral cortex: a light and electron microscopic study

Cortical biopsies of 12 patients with traumatic brain injuries have been used in the present study to examine oligodendroglial cell changes and reactivity. The samples were processed for light and transmission electron microscopy. Four main types of oligodendrocyte populations have been found: resting or unreactive oligodendrocytes, reactive oligodendrocytes, anoxic-ischaemic oligodendroglial cells and hyperthrophic phagocytic oligodendrocytes. The unreactive or resting oligodendrocyte type exhibited a fusiform or elongated shape, a clear or dense band of scarce perikaryal cytoplasm and a nucleus with peripheral heterorocromatin masses. Clear or dense reactive oligodendrocytes showed increased amount of perikaryal citoplasm, dilated endoplasmic reticulum and nuclear envelope, numerous clear, oedematous mitochondria and dense bodies. These oligodendrocytes appeared associated with degenerated myelinated axons. Anoxic-ischaemic oligodendrocytes showed lacunar enlargement of endoplasmic reticulum, dilated Golgi complex and enlargement and disassembly of nuclear envelope. They appeared also in contact with degenerated myelinated axons. Hypertrophic phagocytic oligodendrocytes were observed engulfing the associated degenerated myelinated axons, invading the myelin sheath, separating the myelin lamellae and exerting myelinolitic effects. Oligodendroglialpseudopodic expansions were observed phagocyting the axoplasmic matrix and leaving a huge vacuolar axoplasmic space. The vasogenic and cytotoxic components of traumatic brain oedema are discussed in relation with the oligodendroglial cell changes and reactivity.     

A light and electron microscopic study of oedematous human cerebral cortex in two patients with post-traumatic seizures

Primary objective : Brain cortical biopsies of two patients with clinical diagnosis of complicated brain trauma who had seizures, were studied by means of light and electron microscopes in order to correlate structural alterations with seizure activity.

Methods and procedures : Biopsy samples of left frontal cortex and right parietal cortex were processed by current techniques for light and transmission electron microscopy.

Results : The tissue showed severe vasogenic oedema with perivascular and intraparenchymatous haemorrhages. At the capillary wall, increased vesicular and vacuolar transendothelial transport, open endothelial junctions, thickened basement membrane and swollen perivascular astrocytic end-feet were observed. Some pyramidal and non-pyramidal nerve cells appeared dense and shrunken and others exhibited marked intraneuronal enlargement of membrane compartment. The myelinated axons displayed signs of degeneration and a process of axonal sprouting. Numerous swollen asymmetrical axo-dendritic synaptic contacts were observed in the neuropil, which exhibited mostly closely aggregated spheroidal synaptic vesicles toward the presynaptic membrane and numerous exocytotic vesicles sites. The perisynaptic astrocytic ensheathment appeared retracted or absent, whereas the extracellular space appeared notably dilated. Synaptic disassembly was also observed.

Conclusion : The findings demonstrate, in two patients with post-traumatic seizure activity, brain brarrier dysfunction, vasogenic oedema, anoxic-ischaemic neurons, axonal sprouting, numerous altered excitatory synapses and synaptic disassembly. Some considerations on clinical and research applications are discussed.     

体神经-内脏神经吻合后神经纤维再生过程的光镜电镜观察

目的：观察大鼠体神经-内脏神经吻合后神经纤维的再生。方法：人工建立体神经-内脏神经反射弧大鼠模型，用电镜配合光镜观察12只大鼠术后1、4、8、24周神经变性与再生。结果：术后8、24周大体观察见神经吻合口位置稍许膨大，光镜观察发现术后8周吻合口位置可见新生的轴突，电镜观察见术后1周吻合口及其远近段神经纤维发生Waller变性，术后4周吻合口部位有再生的有髓和无髓纤维，术后8周新生的髓鞘进一步增厚，板层结构清晰可见，术后24周，髓鞘成熟，轴浆富含微管、微丝、线粒体。结论：体神经运动纤维能够再生长入并替代内脏神经节前纤维；再生的神经纤维具备基本正常的周围神经超微结构。     

Structural patterns of injured mitochondria in human oedematous cerebral cortex

Primary objective: Cerebral cortical biopsies of 37 patients with clinical diagnosis of congenital malformations, brain trauma and tumours were studied to establish mitochondrial morphological alterations.

Methods and procedures: Cortical biopsies obtained in the surgical room were immediately processed by conventional technique for transmission electron microscopy.

Results: Three injured mitochondrial morphological patterns were found: swollen clear, (SCM), swollen dense (SDM) and dark degenerated (DDM) mitochondria. SCM were predominantly found in traumatic brain oedema. SDM and DDM were frequently observed in sustained permanent ischaemia induced by brain tumours, vascular anomaly and congenital hydrocephalus. SCM exhibited low electron dense mitochondrial matrix, enlarged intracristal space and continuity of outer and inner mitochondrial membranes. SDM showed high electron dense matrix and swollen intact or fragmented cristae. DDM displayed overall high electron density of matrix and mitochondrial membranes.

Conclusion: The injured mitochondrial patterns are related with nerve cell death and considered markers of lethal nerve cell injury.     

Astrocyte subtypes in the gray matter of injured human cerebral cortex: a transmission electron microscope study

Astrocytic subtypes in different cortical regions of injured human cerebral cortex of 22 patients with brain trauma, vascular anomalies and brain tumours have been examined by means of light microscopy and conventional transmission electron microscopy. The cortical biopsies of frontal, parietal and temporal cortex were examined to analyse the heterogeneous astrocytic response and characterize astrocytic population subtypes. Swollen clear and dense astrocytes, glycogen rich- and glycogendepleted astrocytes, aged or lipofucsin rich-astrocytes and reactive, dark, hypertrophic astrocytes were identified. Clear and dense astrocytes displayed bundles of glial filaments and dense inclusion bodies. Glycogen-rich astrocytes exhibited an accumulation of beta type of monogranular glycogen granules, which disappear in the glycogen-depleted astrocytes, suggesting anoxic mobilization of glycogen stores during ischemia or anoxia. Lipofucsin rich astrocytes were mainly related with ageing processes, although their presence in young patients suggests also an injured related process. Dark astrocytes with phagocytic properties were found. They exhibited bundles of glial filaments. The astrocytic response depended upon the nature of cortical insult, extent of damage, time course of pathological lesion and affected cortical region.     

Glycogen-rich and glycogen-depleted astrocytes in the oedematous human cerebral cortex associated with brain trauma, tumours and congenital malformations: an electron microscopy study

PRIMARY OBJECTIVE: The anaerobic mobilization of astrocyte glycogen in anoxic-ischemic regions of the oedematous human cerebral cortex is analysed. METHODS and PROCEDURES: Seventeen cortical biopsies of patients with brain trauma, brain tumours and congenital malformations were examined by conventional transmission electron microscopy. RESULTS: Glycogen-rich and glycogen-depleted, clear or dense astrocytes cell bodies were observed in anoxic ischaemic regions of different brain cortical areas in perineuronal, neuropilar and perivascular localization. Glycogen-rich astrocytes showed clear or moderately dense cytoplasm and accumulation of both beta-type or monogranular glycogen granules and alpha-type or multigranular glycogen particles. Focal regions of translucent cytoplasm were observed in areas of glycogen degradation. Glycogen-depleted astrocytes exhibited a clear cytoplasm and scarce amount or absence of beta-type glycogen granules. Coexisting glycogen-rich and glycogen-depleted neuropilar astrocytic processes were observed in the vicinity of degenerated myelinated axons and degenerated axodendritic contacts. Glycogen-rich and glycogen-depleted perivascular astrocytic processes were also found surrounding injured and collapsed cerebral capillaries. CONCLUSION: The findings suggest astrocytic glycogen mobilization during anoxic and ischaemic conditions, revealing the important contribution of astrocytes on neuronal survival under conditions of energy substrate limitations.     

Microvascular alterations following cerebral contusion in rats. Light, scanning, and electron microscope study

Cerebral contusion was caused in 18 rats by dropping various weights on an exposed dura of one hemisphere. One or 3 hours after the injury the animals were sacrificed by perfusion with paraformaldehyde-glutaraldehyde solution. The traumatic microvascular and neural tissue alterations were studied with light, scanning, and electron microscopic techniques. The microvascular obstructions and damage were revealed in this study as major histological alterations, causing secondary neural damage. The obstruction of the vessels appeared to have been caused 1) by extravascular pressure from destroyed and swollen tissue, petechial hemorrhage, and dissecting extraluminal clots; and 2) by intravascular clots. Besides the tearing and shearing effects causing petechial hemorrhages, the capillary walls were often thinned and irregular.     

Experimentally induced cerebral aneurysms in rats: VII. Scanning electron microscope study

The luminal surfaces of experimentally induced cerebral aneurysms and the branching sites in the circle of Willis in rats were investigated by scanning electron microscopy. Gap formation at the junctions of the endothelial cells was one of the most obvious changes on the endothelial surface of the aneurysms. Many leukocytes were observed adhering to these gaps. Regressive changes of endothelial cells, such as balloonlike protrusions and craterlike depressions, were also found in the aneurysms. At the branching site, where cerebral aneurysms often develop, endothelial cells were disarranged, rounded, and varied in size. A deep groove was also found adjacent to the apex. The role of endothelial cells and leukocytes in the development of cerebral aneurysms is discussed.     

A study of electrical impedance of oedematous cerebral tissue during operations

Summary In 11 patients, most of whom had cerebral tumours, electrical impedance was recorded during the introduction of an impedance electrode during operation. After removal of the lesion impedance was measured in the tissue adjacent to the walls of the wound cavity. The readings were correlated with water and electrolyte content and with histological findings in the specimens taken from the same places. Electrical impedance appeared to be lowered in regions invaded by tumour and also in the surrounding oedematous areas of white matter. Unless primarily affected, cerebral cortex usually did not show oedema.The increase of water in the oedematous area was accompanied by a proportional increase of tissue Na⁺ and a decrease of tissue K⁺. The method of impedance measurement does not allow the delineation of a tumour from the surrounding oedema.     

Transmission electron microscope observation of morbid nerve segments in neurocausalgia

The authors report the observations by TEM of morbid nerve segment from 3 cases of typical neurocausalgia. It was discovered that a lot of collagen fibrils proliferation, myelin sheaths compressed partly or completely disintegrated and exposed axons. A great number of no myelinic nerve fibers, remained and a great number of macrophages were present, which are morphological characteristics of neurocausalgia.     

Monoclonal antibody labelling of human spermatozoa: an electron microscope study

The antigenic determinants recognized by six anti-human sperm monoclonal antibodies were localized at the subcellular level using an indirect peroxidase immunoelectron microscopic method. Labelling was performed using fresh spermatozoa, and after cell permeabilization (by osmotic shock or freeze-thawing) or detergent demembranation. Two antibodies bound to distinct regions of the plasma membrane, one over the acrosome and the other on the tail, but both also bound to intracellular sites on damaged cells. The internal organelles labelled by the other four antibodies were identified as the acrosomal membrane of the equatorial segment, structures in the connective piece, mitochondrial membranes and axonemal microtubules, respectively. These results are compared with those of a previous immunofluorescence study (Villarroya & Scholler, 1986) and the advantages of joint light and electron microscopy for sperm immunocytochemistry are discussed.     

Pigmented adenoma of adrenal cortex associated with cushing's syndrome Light and electron microscopic study

A pigmented adenoma of the adrenal cortex was surgically removed from a thirty-nine-year-old woman with clinical and biochemical manifestations of Cushing's syndrome. Light and electron microscopic study revealed numerous pigment granules, exhibiting the structural features of lipofuscin in the cytoplasm of the adenoma cells. It appears that adrenocortical adenomas with excessive pigment deposition can be accompanied by increased production of corticosteroid hormones.     

Scanning electron microscope study of human veins and aorta-coronary artery vein grafts.

Scanning electron microscope study of two vein grafts which were removed after 50 months of implantation as aorta-coronary artery vein grafts showed considerable subendothelial thickening, which consisted of relatively cell-poor fibrous layer. In one of the grafts the endothelial surface was intact; the second graft showed focal loss of endothelial cells. Sections of two fresh human veins, studied prior to their insertion as aorta-coronary artery vein grafts, have shown that they retained an intact endothelial layer. A third fresh vein, however, showed focal damage with missing endothelial cells and adherent fibrin.     

Scanning electron microscope study of the development of the human respiratory acinus.

Plastic corrosion casts were made of lungs from fetuses aged from 19 weeks' gestation to term and of lungs from a child and two adults to study the development of the respiratory acinus. To achieve reliable infusion of the most peripheral airspaces a high viscosity plastic was used that is not known to have been employed previously for corrosion casting of lungs. The casts were examined in the scanning electron microscope and showed the increase both in number and in length of the airways distal to the terminal bronchiole and also the change in shape and complexity of the most peripheral airspaces as the lung matures. The terminal airspaces change from short, simple, tubular endings at 19 weeks' gestation to short, shallow saccules from around 30 weeks' gestation to full term and contrast with the deep cup shaped alveoli in the adult. Measurements of the size of the terminal airspace at various stages of development are presented. This new approach, allowing three dimensional study of the peripheral airspaces of the developing lung, will be useful for investigating the lung pathology of neonates.