Bulbar palsy with Rosenthal fiber formation in the medulla of a 15-year-old girl. Localized form of Alexander's disease?

A 15-year-old girl died of a long-standing bulbar palsy that had caused difficult swallowing since early infancy. She was severely malnourished and retarded in growth. Morphologically, the clinical symptoms corresponded to a circumscribed lesion in the enlarged medulla (mega-medulla) that consisted of proliferation of astrocytes, incomplete demyelination, perivascular infiltrates and abundant formation of Rosenthal fibers. Rosenthal fibers were also present in the subpial medullary region where inflammation and astrocytic proliferation were largely absent. This patient's disorder appears to be a localized form of alexander's disease because macrencephaly, Rosenthal fiber formation and leukodystrophy of the cerebral hemispheres and cerebellum were absent. The morphological spectrum of Alexander's disease may now comprise diffuse and localized forms both of adulthood and children.

Differentiation of Medulloblastoma. Studies including immunohistochemical localization of glial fibrillary acidic protein

A series of medulloblastomas was studied by light microscopy. The tumors were variable; astrocytic, ependymal, neuronal, and probable oligodendroglial differentiation was present. Features of glioblastoma multiforme occurred in one case. Immunoperoxidase staining for glial fibrillary acidic protein (GFAP), an antigen found only in astrocytes and ependymal cells, revealed astrocytic differentiation in 11 of 13 cases. The two GFAP-negative tumors were histologically undifferentiated. A new classification of medulloblastomas is presented, based on the multiple types of differentiation of these tumors. Neuronal, astrocytic, ependymal, and small-cell types are described. Undifferentiated tumors were more frequent in younger children. The differentiation of medulloblastoma is correlated with recent experimental studies of gliogenesis and neurogenesis. A hypothesis that medulloblastoma is a stem-cell neoplasm is presented, based on these comparative data.

Ultrastructure of the preretinal membrane in retinitis pigmentosa

Light and electron microscopic examination of the retina and optic nerve in patients with retinitis pigmentosa has revealed a larger of fibrous astrocytes (preretinal membrane) apposed to the inner limiting lamina of the optic nerve retina. This preretinal membrane was centered on the disc, was many cell layers thick over the optic nerve and peripapillary retina, and was tapered to a single cell layer near its anterior margin. Processes of fibrous astrocytes from the optic nerve and peripapillary retina extend into the preretinal membrane through gaps in the inner limiting lamina of the optic nerve and peripapillary retina. The preretinal membrane may be responsible for the abnormally high fundus reflex, the waxy pallor of the disc, and posterior vitreous detachment frequently observed in patients with retinitis pigmentosa.

Fibrous Astrocytes in senile dementia of the Alzheimer type

Fibrous astrocytes were stained by the Sternberger (peroxidase-antiperoxidase) method, using paraffin sections of mid-frontal cerebral cortex of patients with senile dementia and of normals of similar age. The populations of fibrous astrocytes were similar in the molecular layer, but were widely divergent in layers II through VI. Here the mean count of fibrous astrocytes in senile dementia of the Alzheimer type was more than four times that of the normal aged cortex.

Familial dementia of adult onset with pathological findings of a 'non-specific' nature

A family is described in which 4 of 10 siblings developed a dementing illness that culminated in death within five to six years of onset. The pathological findings in 3 members were strikingly similar, and consisted of widespread nerve cell loss and astrocytosis within the cerebral cortex, status spongiosus within the outer cortical layers and, in 2, nerve cell loss and astrocytosis within the dorsomedial nucleus of the thalamus. It is concluded that the disorder described in this report does not conform precisely to any of the currently recognized categories of familial dementing disease.

[Histochemical study of central nervous system lesions in experimental epilepsy caused by kainic acid]

In former investigations on human focal epilepsy and on experimental epilepsy by cobalt implantation, the authors have demonstrated the signaletic importance of "activated astrocytes": cortical astrocytes endowed with a modified metabolism and an accelerated turnover. The present study concerns the results of the intra-amygdaloid injections of kainic acid, a strong excitatory and neurotoxic amino acid. Injections in semi-chronic conditions in the rat lead to electrical and motor seizures and to the production of activated astrocytes not only in regions that might trigger off epileptic seizures (cerebral cortex, amygdala, possibly hippocampus), but also in the neostriatum. Stimulation of this last region results in a Huntington chorea-like syndrome. Thus, the importance of activated astrocytes must be extended to include other conditions of intense hyperactivity of neurons than epilepsy.

Distribution of cerebral lesions in acquired hepatocerebral degeneration

The brain lesions of our patients with chronic portal-systemic venous shunts were much the same regardless of the presence or absence of primary liver disease. Alzheimer's type 2 abnormality of astrocytes and demarcated areas of spongy degeneration were found, mainly in the grey matter, with more severe involvement of the basal ganglia and the deeper layers of the frontal, parietal and occipital cortex. The spongy degeneration showed an especially close correlation with the arterial blood supply, being greatest in borderland areas that fall between the regions usually supplied by one or other of the major cerebral arteries. Previous investigations have not been primarily concerned with selective vulnerability so that comparisons are difficult, but on review, there is evidence that this pattern of involvement is a feature of both Wilson's disease and acquired hepatocerebral degeneration. The toxic effect of the portal blood is greatest in the grey matter, probably because of the greater metabolic activity there, and the distribution of lesions within this area of greater vulnerability appears to be further influenced by circulatory factors.

Astrocytes of the cerebral cortex in hepatosplenic schistosomiasis mansoni and in liver cirrhosis. A morphological, quantitative and karyometric study

A morphological, quantitative and karyometric study of astrocytes of the cerebral cortex in patients with liver cirrhosis, hepatosplenic schistosomiasis mansoni and controls is reported. Cell proliferation was commonly seen but there was no significant increase in number of astrocytes in either cirrhosis and schistosomiasis groups. A highly significant increase in astrocyte nuclear volume in cirrhosis and schistosomiasis in relation to controls was observed. The astrocyte average nuclear volume in the cirrhotics was also significantly increased in relation to the schistosomiasis group. From the present data and those reported by other investigators it may be concluded that under normal conditions the astrocyte population is continually reforming and it proliferates in liver cirrhosis and hepatosplenic schistosomiasis. It seems that the morphological, quantitative and karyometric astrocyte changes in schistosomiasis may be the result of the same factors as those previously described for liver cirrhosis and experimental portacaval shunt.

Demonstration of astrocytes in cultured amniotic fluid cells of three cases with neural-tube defect

We have investigated the origin of rapidly adhering (RA) cells in three cases of neural tube defects (two anencephali, one encephalocele). We were able to demonstrate the presence of glial fibrillary acidic (GFA) protein in variable percentages (4--80%) of RA cells cultured for 4--6 days by use of indirect immunofluorescence with GFA antiserum. Cells cultured from amniotic fluids of normal pregnancies and fetal fibroblasts were completely GFA protein negative. GFA protein is well established as a highly specific marker for astrocytes. Demonstration of astrocytes may prove to be a criterion of high diagnostic value for neural tube defects. The percentage of astrocytes decreased with increasing culture time, while the percentage of fibronectin positive cells increased both in amniotic fluid cell cultures from neural tube defects and normal pregnancies.

Gangliogliomas: pathological and clinical correlation

Fourteen cases of ganglioglioma are analyzed. This tumor can be found anywhere within the central nervous system. The histological appearance is highly variable and does not relate to the biological behavior. The prognosis depends on the location and possible modes of treatment. Overall, the lesion appears to be nonaggressive and consistent with long survival.

Olivary enlargement: chronological and morphometric analyses

Chronologic and morphometric changes in the inferior olivary nucleus of the human medulla oblongata were studied in eight cases of primary pontine hemorrhage with different survival periods. To measure the olivary areas and analyze the neuronal and glial components, an optic electronic planimeter was used. A desk-top computer was also used for the calculation of the obtained data. The olivary enlargement was observed in cases with survival periods ranging from 3 weeks after the onset to 9.5 months. A morphometric analysis revealed six different stages of olivary changes after the destruction of the central tegmental tract in the pons: (1) no olivary changes, (2) olivary amiculum degeneration, (3) olivary hypertrophy, (4) culminant olivary enlargement, (5) olivary pseudohypertrophy, and (6) olivary atrophy. In stage (3) - noticed here for the first time -, neuronal cellular hypertrophy and sclerotic neurons with "insect-bite appearance" were observed. In stages (4) and (5), we also found the presence of prominent gemistocytic astrocytes in the characteristically enlarged inferior olivary nuclei. However, no proliferation of astrocytes during the olivary enlargement was confirmed in the morphometric analysis.

The measurement of biological age

One of the objectives of gerontological research is to achieve, reproducibly and at will, a verifiable discrepancy between the chronological and biological age of organisms. To accomplish this, the experimenter must be in a position to measure biological age independently. In theory, this can be done in the three ways: by actuarial analysis of large populations, assessment of overall morbidity, or observation of chronic degenerative changes that can be actually measured or graded according to a scale. Of these three approaches, only the last appears to be promising in experimental research. However, not all progressive degenerative changes represent practically useful parameters of biological age. Criteria for their evaluation are presented, and their theoretical prerequisites as well as concrete applications discussed. In a more general way, one has to be aware that biological age is a statistical entity. It cannot be directly observed but only inferred from quantifiable epiphenomena, and is, as such, not measurable like temperature or weight.

Chronic demyelination inhibits remyelination in the central nervous system. An analysis of contributing factors

The remyelinative capacity of the central nervous system was investigated in the superior cerebellar peduncles of mice chronically demyelinated for 6 to 7 months by the administration of Cuprizone. It was found that, although the axons retained their capacity for remyelination, this capacity was greatly reduced compared to acutely demyelinated animals. The possible causes for this reduction were examined, and it was concluded that the limiting factor was the decreased availability of oligodendrocytes for remyelination, rather than inherent factors in the axons, or changes in the surrounding glial environment. The implications for both experimental and clinical disease are discussed.

Long-term morphology of the alumina cream experimental epileptogenic focus

A morpholigical study of an experimental epileptogenic focus in the cat, eighteen months after intracerebral injection of alumina cream, is presented. The most significant histological findings were cortical atrophy and reactive gloisis enclosing the implantedd particles. Subpial sclerosis and evidence of ischaemic neuronal lesions were also found. These findings confirm a close morphological relation between the alumina cream experimental focus obtained after a certain period of evolution and the human epileptogenic focus.

Nature of the reversible white matter lesion in multiple sclerosis. Effects of acute inflammation on myelinated tissue studied in the rabbit eye

Arthus reactions of different intensities were induced in the rabbit eye using measles vaccine as the immunogen. In the presence of a mild Arthus reaction in the vitreous, myelinated nerve fibre bundles on the retinal surface revealed extracellular oedema together with marked swelling and rupture of astrocyte processes, including those bearing a special relationship to nodes of Ranvier. These changes improved or disappeared over the course of six days. No demyelination occurred. The findings implicate an astrocytic lesion as a possible cause of reversible neurological deficit and conduction block associated with acute inflammation in central white matter.

Chorea gravidarum. Report of a fatal case with neuropathological observations

In a 23-year-old primigravida with no prior history of rheumatic fever, choreiform movements developed late in the third trimester, and she died in a state of hyperthermia 14 days later. Results of neuropathological examination showed, as the basis for the chorea, nerve cell loss and astrocytosis within the striatum (especially the caudate nucleus). Anaylsis of the case in conjunction with a review of the literature strongly suggests that chorea gravidarum should be regarded as a syndrome rather than a specific disease entity.

Chemical injury of the spinal cord of the rabbit after intracisternal injection of gentamicin: an ultrastructural study

We previously reported that rabbits with quadriplegia, after a single intracisternal injection of gentamicin sulfate, have multiple minute lesions in the white matter of the upper cervical spinal cord and the lower medulla oblongata, most marked at the C2 segment, when light microscopy is used to study the histopathologic changes. Using electron microscopy in the present investigations, we have found that 9 hours after injection of gentamicin sulfate there was marked edema of fibrous astrocytes in the soma and processes of glia limitans. Ribosomes were disarranged. Mitochondria were swollen, the matrix density was increased and contained paracrystalline lattice structure, and the cristae were reduced in number. Oligodendrocytes displayed hypertrophy, with proliferation of smooth ER, ribosomes, microtubules, Golgi complexes, and lysosomes. A few axons were subsegmentally swollen due to axoplasmic edema. At 24 hours, the lesions became obvious by light microscopy. Astrocytes were more edematous and oligodendrocytes remained hypertrophic. Myelin sheaths were tumefied by dissociation of myelin lamellae. Axons were edematously swollen. Lysed axons were surrounded by lysed myelin sheaths. At 48 hours, numerous neuroaxonal end bulbs were formed at the lysed end. Wallerian degeneration was also evident. The data suggest that oligodendroglia actively react to detoxify gentamicin, astroglia become severely edematous but survive, and axons and myelin sheaths are lysed in reaction to the toxicity of gentamicin. The unique distribution of gentamicin lesions in the deeper white matter, with sparing of the overlying marginal myelinated fibers, seems to depend primarily upon the distribution of edematous astrocytes, which are most sensitive to this noxious chemical. Since gentamicin is apparently detoxified by oligodendroglia, the regenerative process of axons starts after a short period of axonal lysis.

Glial fibrillary acidic protein and Alzheimer-type senile dementia

Glial fibrillary acidic protein (GFAP), a protein that is associated with 9-nm filaments of astrocytes, was observed to be increased in the astrocytes surrounding senile plaques in patients with Alzheimer dementia and in aged subjects without dementia. A few GFAP-positive fibers were seen in the centers of plaques. These results emphasized the selectivity of senile changes; whereas some cells seemed to undergo degeneration or dysfunction, other cells--astrocytes--maintain their capacity for reaction and may increase the formation of at least one protein, GFAP.

Neuroglial tissue in human eighth nerve specimens

One hundred eighty nerve biopsy specimens from patients with eighth nerve tumors or other vertiginous diseases requiring vestibular neurectomy were studied. In many specimens light microscopy revealed pale areas among the myelinated nerve fibers in the neurolemmal portion of the eighth nerve. Electron microscopy showed that these were ectopic areas of glial tissue consisting of bundles of numerous cytoplasmic processes of fibrous astrocytes. The abundance of filaments within each process and the occurrence of microtubuli suggest that these processes are reactive astrocytes and accordingly are present as a consequence of the reparative potential of the astroglial tissue after a neuronal lesion. The possible functional significance of the findings is discussed.

Morphological changes in acute focal ischemia: response to osmotherapy

The sequential morphological changes following acute MCA occlusion in conscious cats were studied. The artery was occluded with a simple implanted device that resulted in immediate contralateral hemiparesis. The ischemic changes in the MCA territory developed in a diphasic fashion. Astrocytic swelling and capillary narrowing preceded the development of ischemic neuronal alterations during the primary phase. Capillary obstruction developed during the secondary phase when tissue injury was advanced. Increased vascular permeability to fluorescein was seen with 90 min of MCA occlusion and was initially confined to ischemic gray matter. Leakage of fluorescein consistently occurred with occlusion periods of 90 min and longer, whereas increased permeability to Evans blue was transient. A single, standard dose of mannitol (1.0 to 1.2 g/kg i.v.) was shown to improve the neurological deficit and delay the onset of ischemic injury. Considerable preservation of cerebral tissue was demonstrated with ischemic periods up to 6 hr. The administration of small (0.5 g/kg i.v.), repeated doses of mannitol was found to prolong the beneficial effects.

Experimental transmission of human subacute spongiform encephalopathy to small rodents. I. Clinical and histological observations

Experimental transmission of subacute spongiform encephalopathy from three human cases to small rodents is reported. The first case with atypical CJD with spongiform change, kuru plaques, and leukomalacia was transmitted directly to mice, rats, and guinea pigs and indirectly to hamsters and Mongolian gerbils through rats. From two other typical SSE cases the disease was also successfully transmitted; from he second case to mice and rats, and from the third case to guinea pigs. Brain showed the highest infectivity; the spleen, liver, blood, and cerebrospinal fluid of diseased animals were also infective. Intracerebral inoculation was the route for the fastest transmission, followed by intrathecal, intraperitoneal, submucosal, and subcutaneous routes. The incubation periods and clinical features were characteristic in each inoculated species and did not vary within several passages, except for the shortening of incubation period from the first to the second passage. Histologically, a marked spongy state and proliferation of astrocytes were observed in all diseased animals, though the distribution of the lesion was peculiar to each species. The severe lesion in the white matter in mice was similar to that seen in mice inoculated with scrapie and also to that seen in the first case.

Creutzfeldt-Jakob disease with extensive degeneration of white matter

Degeneration of the white matter is uncommon is Creutzfeldt-Jakob disease (CJD), and when it occurs is usually mild, and limited in distribution. In the case of 77-year-old woman with CJD lasting 1 year, there was extensive degeneration of cerebral white matter in addition to severe loss of neurons and hypertrophic astrogliosis in cortex and striatum. The extent and severity of white matter lesions makes the case unusual.

A quantitative histological study of the effects of acute triethyl lead poisoning on the adult mouse brain

The effects of a single injection of triethyl lead chloride on the mouse brain was studied 1, 3, 5, 7 and 30 days postinjection using quantitative histological techniques. The total number of glia in the anterior commissure was significantly reduced following injection but by 30 days postinjection had returned to normal. The number of neurons and the number of glia in the indusium griseum did not change significantly. The number of mitotic cells in the subependymal layer fell slightly from 1 to 3 days postinjection then returned to normal 5 days postinjection. The number of pyknotic cells in the subependymal layer did not appear to change following injection. In the anterior commissure the number of mitotic cells fell significantly from 1 to 3 days postinjection and then increased significantly at 5 days postinjection. A similar increase in mitosis was found at 5 days postinjection in the indusium griseum. At 7 days postinjection a significant decrease occurred in pyknotic cells in the anterior commissure and indusium griseum. Changes in the percentage of each type of glial cell present were found 30 days postinjection. This suggests that although the total number of glia may return to normal the number of each type of glial cell present changes following injection of triethyl lead. There was no evidence of cerebral oedema following triethyl lead injection either at the light or electron microscopic level.

Early onset and topographical distribution of hypertrophied astrocytes in hippocampus of aging rats: a quantitative study

Our results indicate that the density of astrocytes exhibiting hypertrophy in the hippocampus increases dramatically and progressively with age, being significantly elevated even in mid-life (13 month) animals. However, the total population of astrocytic cells (hypertrophied and nonhypertrophied) in the quantified region is not significantly elevated. Further, the relative distributions of both hypertrophied and total glial cells remained remarkably constant at the three ages measured. Reactive hypertrophy of astrocytes therefore appears to occur "in place" and migration of astrocytes does not appear to be a major factor in the hippocampus during aging. Of particular note was the finding that astrocyte hypertrophy is far more prominent in synaptic terminal fields than in myelinated fibers of the same system.

Quantitative changes in astrocytes after portacaval shunting in chimpanzees and in man with normal liver parenchyma

Chimpanzees without liver cell damage, but subjected to portacaval anastomosis, showed behavioral changes that were accompanied by "Alzheimer II" astrocyte hyperplasia and nuclear enlargement. These findings were similar to those in a human patient with encephalopathy, secondary to a portacaval shunt, whose liver was normal. Controlled quantitative study of astrocytic hyperplasia in different anatomic regions showed the hyperplasia to involve the gray matter with only moderate topographic variation. Individual degrees of hyperplasia somewhat paralleled the severity of clinical symptoms and ammonia levels; no clear-cut relationship with time after shunting could be established. Portacaval shunt encephalopathy in chimpanzees greatly resembles that in man and, thus, lends itself to more detailed experimental analysis.

Lymphocytes within glial cells ("emperipolesis") in a case of a granular cell tumor

A case of a combined neurofibroma - granular cell tumor of the left middle cranial fossa with infiltration of the temporal lobe and expansion into the orbit is presented. The granular cell tumor shows big fibrillary astrocytes in its peripheral zone. Even in the tumor-free brain tissue adjacent to the tumor plenty of these obviously reactively proliferated astrocytes are found. Furthermore, lymphocytes within the cytoplasm of such astrocytes ("emperipolesis") strike the eye. Neither the lymphocytes nor the astrocytes show signs of damage. A review of the literature and the theories concerning the phenomenon of emperipolesis are given. The problem of its biological significance and the question whether emperipolesis is the result of invasion of engulfment must remain unsolved.

Abnormal neuronal migration, deranged cerebral cortical organization, and diffuse white matter astrocytosis of human fetal brain: a major effect of methylmercury poisoning in utero

Detailed clinical and neuropathological studies have been made in two fullterm newborn human infants who were exposed to methylmercury in utero as a result of maternal ingestion of methylmercury-contaminated bread in early phases of pregnancy. High levels of mercury were detected in various regions of the brain at autopsy. Study of the brains revealed a disturbance in the development in both cases, consisting essentially of an incomplete or abnormal migration of neurons to the cerebellar and cerebral cortices, and deranged cortical organization of the cerebrum. There were numerous heterotopic neurons, both isolated and in groups, in the white matter of cerebrum and cerebellum and the laminar cortical pattern of the laminar cortical pattern of the cerebrum was disturbed in many regions as was shown by the irregular groupings and the deranged alignment of cortical. Prominent in the white matter of the cerebrum and the cerebellum was diffuse gemistocytic astrocytosis accompanied by an accumulation of mercury grains in their cytoplasm. These findings indicate a high degree of vulnerability of human fetal brain to maternal intoxication by methylmercury. A major effect appears to be related to faulty development and not to destructive focal neuronal damage as has been observed in mercury intoxicaiton in adults and children exposed postnatally.

Astrocytic hamartoma of the retina not associated with tuberous sclerosis

A 6-year-old boy had a peripapillary lesion diagnosed as retinal astrocytic hamartoma, which was not associated with tuberous sclerosis, neurofibromatosis, or intraocular extension of a glioma. The patient was observed for nine years, during which time the lesion grew significantly. Because of this growth and the evidence of proximal optic nerve involvement on computed tomography, radiation therapy was administered with a resultant marked reduction in visual acuity. The eye was subsequently enucleated. The enucleated eye was studied by both light and transmission electron microscopy. The specimen had a retinal astrocytic hamartoma with sparse vascularization and only superficial optic nerve involvement. Additionally, it revealed optic nerve drusen in varying stages of development, significant accumulations of subretinal macrophages, and an almost total loss of retinal outer segments with the preservation of the retinal pigment epithelium.

Glial bridges and Schwann cell migration during chronic demyelination in the C.N.S

The formation of fibrotic bridges from subpial astrocytes into the subarachnoid space of the spinal cord and the migration of Schwann cells to the central nervous system (C.N.S.) is appraised in chronically demyelinated C.N.S. lesions. Spinal cord tissue was studied from inbred, Strain 13 guinea pigs with chronic experimental allergic encephalomyelitis (EAE). It has been found that uncommitted Schwann cells are present around remyelinated fibres in nerve root entry zones, between meningeal cells at a distance from the roots and along blood vessels within the spinal cord parenchyma. It is speculated that these cells migrate via the above route to the C.N.S. In the present model, this invasion might be aided by glial fibrosis, a process which leads to surface irregularities in the spinal cord, an extensive extracellular space and possible breaches in the glia limitans through which Schwann cells might penetrate.

Cerebral hypoperfusion in the sudden infant death syndrome? Brainstem gliosis and vasculature

Gliosis is increased in the respiratory control area of the brainstem in victims of sudden infant death syndrome (SIDS), as it is in infants who have died of congenital heart disease. In the latter, the lesions appear to result from hypoxia or ischemia, and studies of the brainstem microvasculature of SIDS victims indicated a close relationship between the gliosis and adjacent vasculature. It is postulated that cerebral hypoperfusion may play a role in SIDS.

Cellular reactions to subependymal plate haemorrhage in the human neonate

The most important cause of death in human premature babies at the present time is intraventricular haemorrhage consequent to haemorrhage in the subependymal plate. Lesser degrees of plate haemorrhage can also have serious effects. It was possible to observe the reaction to such haemorrhages in twenty-seven cases whose range of gestational age extended from 23 to 36 weeks and survival from 4 to 59 days. The haemorrhage occurs in the first week of life, usually in the first few days. The earliest reaction at 4 days was the presence of mononuclear phagocytes around the haemorrhage, these evolved to iron pigment macrophages which were present in eighteen of the twenty-two cases in which some reaction was detected. Subependymal astrocytic proliferation was seen at 11 days, related to ependymal disruption, but an astrocytic reaction around the haemorrhage and related to it was not seen until 14 days. Within the subependymal plate this reaction was scanty in fibril production and the cells were thought to be derived from differentiating astrocytes in the plate. In one case a more marked reaction was detected to hypoxic damage in the adjacent thalamus. The source of the phagocytes in these sites and the reasons for the rather slow astrocytic reaction are discussed.

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.

Transmissible virus dementia. II. Neurohistology of three, geographically clustered cases of Creutzfeldt-Jakob disease

Histopathological findings in three temporo-spatially linked cases of Creutzfeldt-Jakob disease (CJD) are reported. The patients were males, unrelated and without positive family history. Their mean age at the onset of the disease was 52.3 years. The mean duration of the illness was 6.6 months; the clinical symptomatology differed considerably. Neurohistology revealed in all patients a neuronal loss, intracyoplasmic vacuolation, spongiosis and astrocytosis. Besides the cortical regions, basal ganglia and cerebella were severely affected. All cases were pathologically suggestive of the cortico-striato-cerebella variant of CJD. Attention is drawn to this apparent topical similarity of most pronounced lesions. The possible significance of the pathoanatomical consistency, observed in the cases studied, for the unusual pattern of natural occurrence of CJD is considered.

Arrest of myelination and demyelination in rabbit retina induced by herpes simplex virus infection

Herpes simplex virus was injected into the vitreous of suckling and adult rabbits. In the suckling rabbits the infection caused an arrested myelination of the strip. Further, the infected strips showed degenerative changes with splitting and distension of myelin sheaths which then disintegrated. Ultrastructurally, herpes simplex virus particles were found in both oligodendroglial cells and in astrocytes in the bundles. No increase in intraocular pressure was recorded during the inflammation. The infection spread along optic pathways to the opposite side. Inflammatory cells appeared at the surface and infiltrated the degenerating strip. Especially in the contralateral eye, an extensive inflammatory cell infiltration was seen among bundles of nerve fibres which showed partly well-preserved myelin and partly with signs of demyelination reminiscent of the picture of experimental allergic encephalomyelitis in the epiretinal strip.