Van Gehuchten Research Articles

Electron microscopic serial-sectioning/reconstruction study of parvalbumin-containing neurons in the external plexiform layer of the rat olfactory bulb.

Neurons containing a calcium-binding protein parvalbumin in the external plexiform layer of the rat olfactory bulb were identified light microscopically with the pre-embedding immunocytochemistry and were subsequently analysed with the electron microscopic serial-sectioning and three-dimensional reconstructions. In the present study we chose several different types of parvalbumin-immunoreactive neurons identified light microscopically as Van Gehuchten cell type, superficial short-axon cell type and multipolar cell type. Parvalbumin-immunoreactive somata were similar to one another in their ultrastructural characteristics, showing nuclear indentations, moderately developed Golgi apparatus and abundant mitochondria; these structural features appeared to resemble those of the short axon cells around the glomeruli and in the granule cell layer reported in previous electron microscopic studies. All neurons analysed in the present study made symmetrical synapses on to dendrites and somata of presumed mitral/tufted cells and received asymmetrical synapses from them, and occasionally formed reciprocal synapses with them. On the parvalbumin-immunoreactive processes, the asymmetrical synapses nearly equalled the symmetrical ones in number and about 30-50% of them were identified as reciprocal pairs. In contrast, no presynaptic sites were observed on parvalbumin-immunoreactive somata, and thick portions (more than approximately 2 microns in diameter) of the proximal dendrites, where they were occasionally postsynaptic in some asymmetrical and symmetrical synapses from parvalbumin-immunonegative profiles. Characteristically, parvalbumin-immunoreactive process frequently make direct contacts with one another; processes regarded light microscopically as arising from a soma or a dendrite or parvalbumin-immunoreactive neurons were sometimes revealed to be separate but directly contacting processes with electron microscopic examinations. Although puncta adherentia were occasionally observed between these contact sites, so far neither gap junctions nor chemical synapses were observed. Until now, it has been believed that in the external plexiform layer only granule cells form reciprocal synapses with mitral/tufted cells. However, the present study clearly demonstrates that interneurons different from granule cells, namely GABAergic neurons containing a calcium-binding protein parvalbumin, also make reciprocal synapses with mitral/tufted cells in the external plexiform layer. Therefore, neuronal processes making reciprocal synapses with mitral/tufted cells in the external plexiform layer cannot be determined a priori as granule cell processes.

Primary Human Immunodeficiency Virus Infection Presenting as Myopericarditis and Rhabdomyolysis

Journal Article Primary Human Immunodeficiency Virus Infection Presenting as Myopericarditis and Rhabdomyolysis Get access Marie-Paule Guillaume, Marie-Paule Guillaume Departments of Internal Medicine and Clinical Biology (Virology Unit), Brugmann University Hospital, Free University of Brussels, and the Department of Microbiology, Erasme University Hospital, Free University of Brussels (U.L.B.), Brussels, Belgium Reprints or correspondence: Dr. M. P. Guillaume, Department of Internal Medicine, Brugmann University Hospital, 4, place Van Gehuchten, 1020 Brussels, Belgium. Search for other works by this author on: Oxford Academic PubMed Google Scholar Danièle Van Beers, Danièle Van Beers Departments of Internal Medicine and Clinical Biology (Virology Unit), Brugmann University Hospital, Free University of Brussels, and the Department of Microbiology, Erasme University Hospital, Free University of Brussels (U.L.B.), Brussels, Belgium Search for other works by this author on: Oxford Academic PubMed Google Scholar Marie-Luce Delforge, Marie-Luce Delforge Departments of Internal Medicine and Clinical Biology (Virology Unit), Brugmann University Hospital, Free University of Brussels, and the Department of Microbiology, Erasme University Hospital, Free University of Brussels (U.L.B.), Brussels, Belgium Search for other works by this author on: Oxford Academic PubMed Google Scholar Jacques Devriendt, Jacques Devriendt Departments of Internal Medicine and Clinical Biology (Virology Unit), Brugmann University Hospital, Free University of Brussels, and the Department of Microbiology, Erasme University Hospital, Free University of Brussels (U.L.B.), Brussels, Belgium Search for other works by this author on: Oxford Academic PubMed Google Scholar Elie Cogan Elie Cogan Departments of Internal Medicine and Clinical Biology (Virology Unit), Brugmann University Hospital, Free University of Brussels, and the Department of Microbiology, Erasme University Hospital, Free University of Brussels (U.L.B.), Brussels, Belgium Search for other works by this author on: Oxford Academic PubMed Google Scholar Clinical Infectious Diseases, Volume 21, Issue 2, August 1995, Pages 451–452, https://doi.org/10.1093/clinids/21.2.451 Published: 01 August 1995 Article history Received: 29 July 1994 Revision received: 14 November 1994 Published: 01 August 1995

Calcium-binding protein parvalbumin-immunoreactive neurons in the rat olfactory bulb. 1. Distribution and structural features in adult rat.

The laminar distribution and morphological features of parvalbumin-immunoreactive [PV(+)] neurons, one of the subpopulations of GABAergic neurons, were studied in the rat olfactory bulb at a light microscopic level. In the main olfactory bulb of adult rats, PV(+) neurons were mainly located in the external plexiform layer (EPL), and a few were scattered in the glomerular layer (GL), mitral cell layer (ML), and granule cell layer (GRL); whereas PV(+) neurons were rarely seen in the accessory olfactory bulb. The inner and outer sublayers of the EPL (ISL and OSL) appeared to be somewhat different in the distribution of PV(+) somata and features of PV(+) processes. PV(+) somata were located throughout the OSL, and PV(+) processes intermingled with one another, making a dense meshwork in the OSL; whereas, in the ISL, PV(+) somata were mainly located near the inner border of the EPL, and PV(+) processes made a sparser meshwork than that in the OSL. PV(+) neurons in the EPL were apparently heterogeneous in their structural features and appeared to be classifiable into several groups. Among them there appeared five distinctive types of PV(+) neurons. The most prominent group of PV(+) neurons in the OSL were superficial short-axon cells, located in the superficial portion of this sublayer and giving rise to relatively thick processes, in horizontal or oblique directions, which usually bore spines and varicosities. Another prominent group of PV(+) neurons extended several short, branched dendrites with spines and varicosities, which appeared to intermingle with one another, making a relatively small, spherical or ovoid dendritic field around the cell bodies; most of them resembled Van Gehuchten cells reported in previous Golgi studies. A third distinctive and most numerous group of PV(+) neurons were of the multipolar type; their somata and processes were located throughout the EPL. Their relatively smooth processes with frequent varicosities and a few spines were extended horizontally or diagonally throughout the EPL. A fourth group, which could be a subtype of the multipolar type, were located in or just above th ML and extended several thin, smooth dendrites in the EPL, some of which appeared to reach the border between the GL and EPL. Occasionally, axon-like processes arose from their cell bodies and extended into the ML. This fourth type of PV(+) neuron was named inner short-axon cells. A fifth group of neuron was located in the ML; processes of these neurons were extended horizontally, so they were named inner horizontal cells.(ABSTRACT TRUNCATED AT 400 WORDS)

Calbindin D-28K and NADPH-diaphorase activity are localized in different populations of periglomerular cells in the rat olfactory bulb

Calbindin D-28k (CaBP) immunocytochemistry and NADPH-diaphorase (ND) histochemistry have been combined in the rat olfactory bulb by successive incubations of the same sections. The outer strata showed a similar neuronal staining pattern for both markers with positive periglomerular neurons (although the CaBP-stained periglomerular cells were six-fold more abundant than the ND-active ones) and larger neurons scattered in the glomerular and external plexiform layers. Both populations of periglomerular cells were distinct but they did not show specific morphological characteristics nor a predominant distribution around ND-positive and negative glomeruli. The colocalization study demonstrates that the larger ND and CaBP-stained juxtaglomerular cells, identified according to their size, location and processes branching patterns as two types of short axon cells (superficial short-axon and Van Gehuchten Cells) were also independent populations.

Calbindin D-28k-positive neurons in the rat olfactory bulb. An immunohistochemical study.

We have studied the distribution of calbindin D-28k immunoreactivity in the rat olfactory bulb using specific monoclonal antibodies and the avidin-biotin-immunoperoxidase method. The largest number of positive neurons was located in the periglomerular layer. These neurons were identified as periglomerular cells; they have been described also by other authors as calbindin-positive elements. Close to these neurons, a second population of nerve cells was identified as superficial short-axon neurons. The remaining layers showed a smaller number of stained elements. Other labeled neurons were located along the external border of the external plexiform layer; the scarce neurons marking its internal border were identified as van Gehuchten cells. No immunoreactive structures were found in the mitral cell layer, although we observed another population of immuno-stained short-axon cells at its internal border. Some reactive structures, identified by us as horizontal and vertical cells of Cajal, were located in the boundary zone between the internal plexiform layer and the granule layer. In the white matter, we found a neuronal type characterized by its large size and oriented arborization of varicose dendrites.

Acute nonlymphocytic leukemia following chemotherapy with cisplatin and etoposide for non-small-cell carcinoma of the lung: case report : Brenez D, Devriendt J, Lenclud C, Schmerber J. Service de Medecine Interne, Hopital Universitaire Brugmann, Place A. Van Gehuchten 4, 1020 Brussels. Cancer Chemother Pharmacol 1990;26:235–236

Acute nonlymphocytic leukemia following chemotherapy with cisplatin and etoposide for non-small-cell carcinoma of the lung: case report : Brenez D, Devriendt J, Lenclud C, Schmerber J. Service de Medecine Interne, Hopital Universitaire Brugmann, Place A. Van Gehuchten 4, 1020 Brussels. Cancer Chemother Pharmacol 1990;26:235–236

Structure of the olfactory bulb of the hedgehog (Erinaceus europaeus): A Golgi study of the intrinsic organization of the superficial layers

The intrinsic organization of the mitral cell, external plexiform, and glomerular layers of the main olfactory bulb of the insectivore hedgehog were studied with the Golgi method. This study completes our previous description of the cell types in the granule cell layer in the same subject (López-Mascaraque et al., J. Comp. Neurol. 253:135-152, '86). In the present contribution the morphology of mitral, internal, and middle tufted cells is described with particular interest in the formation and arrangement of glomerular tufts by the primary dendrites, and the disposition of the secondary dendrites. Three types of intrinsic cells were found in the external plexiform layer: Van Gehuchten cells, satellite cells, and horizontal cells. All these cells display unusual patterns of branching processes that were difficult to classify as dendritic or axonal. The close relationship between some processes of the satellite cells with the mitral or tufted cell dendrites is noted, suggesting that these cells may be inhibitory in nature. The external tufted cells are described, and several aspects pertaining to their morphology were considered in order to distinguish them from periglomerular cells and from the remaining tufted cells. External tufted and periglomerular cells appear to be intrinsic neurons, having axons distributed in the periglomerular region, most probably devoted to relating different olfactory glomeruli. The arrangement of glomeruli in the glomerular layer and distinctive characteristics with respect to other mammals were considered from a comparative point of view.

VIP‐and PHI‐immunoreactivity in olfactory centers of the adult cat

The purpose of the study was to determine the morphology and distribution of vasoactive intestinal polypeptide- and peptide histidine isoleucine-immunoreactive (VIP- and PHI-ir) neurons and innervation patterns in the main and accessory olfactory bulb, anterior olfactory nucleus, and piriform cortex of the adult cat. In these centers, VIP- and PHI-immunoreactive material are present in the same neuronal types, respectively, therefore summarized as VIP/PHI-ir neurons. In the main olfactory bulb, the majority of VIP/PHI-ir neurons are localized in the external plexiform layer. These neurons give rise to two or more locally branching axons. They form boutons on mitral and external tufted cell bodies. According to the morphology and location, we have classified these neurons as Van Gehuchten cells. Some VIP/PHI-ir neurons are present in the glomerular layer. They have small somata and give rise to dendrites branching exclusively into glomeruli. We have classified these neurons as periglomerular cells. In the granule cell layer, neurons with long apical dendrites and one locally projecting axon are present. In the accessory olfactory bulb, VIP/PHI-ir neurons are localized in the mixed external/mitral/internal plexiform layer. They represent Van Gehuchten cells. In the anterior olfactory nucleus and piriform cortex, VIP/PHI-ir bipolar basket neurons are present. They are localized mainly in layers II/III. These neurons are characterized by a bipolar dendritic pattern and by locally projecting axons forming basket terminals on large immunonegative cell somata. Because of their common morphological features, we summarize them as the retrobulbar VIP/PHI-ir interneuron population. The PHI-ir neurons display the same morphology as the VIP-ir cells. However, they are significantly lower in number with a ratio of VIP-ir to PHI-ir cells about 2:1 in the main and accessory olfactory bulb and in the anterior olfactory nucleus. By contrast, in the piriform cortex the ratio is about 1:1.

Glutamic‐acid‐decarboxylase‐ and parvalbumin‐like‐immunoreactive structures in the olfactory bulb of the human adult

This study examines the distribution and morphological characteristics of glutamic-acid-decarboxylase-like (GAD)- and parvalbumin-like (PA)-immunoreactive structures in the olfactory bulb of the human adult. GAD-immunoreactive somata occurred in the glomerular layer, the external granule cell layer, the more superficial portion of the external plexiform layer, and the internal granule cell layer. The cells were small- to medium-sized. Demonstration of lipofuscin pigment revealed the presence of unpigmented as well as pigmented neurons, thus suggesting the existence of two subpopulations of GAD-positive neurons. GAD-immunoreactive puncta and/or fibers were mainly seen in the periglomerular region and the internal granule cell layer. All other layers of the bulb, as well as the intrabulbar portion of the anterior olfactory nucleus, displayed considerably less of these puncta and/or fibers. The olfactory nerve layer remained practically clear of immunoreactive material. PA-immunoreactive somata occurred in the glomerular layer and both the external and internal granule cell layer. Only a small number of immunoreactive nerve cells were encountered within the white matter or the olfactory tract. Most PA-positive neurons displayed characteristics of short axon cells whereas a few others resembled van Gehuchten cells. All of the PA-immunoreactive neurons were devoid of lipofuscin pigment. Immunoreactive puncta and fibers were present in all layers though predominating in the periglomerular region, the olfactory nerve layer, and the internal granule cell layer. The intrabulbar portions of the anterior olfactory nucleus did not show any immunoreactive structures.

Vasoactive intestinal polypeptide-immunoreactive neurons in the main olfactory bulb of the hedgehog (Erinaceus europaeus).

Vasoactive intestinal polypeptide (VIP) immunoreactivity was localized by the indirect antibody enzyme method (PAP technique) in the main olfactory bulb of the hedgehog. Most VIP-immunoreactive cells were located in the glomerular layer and throughout the external plexiform layer. Fewer cells were observed in the granule cell layer. At the morphological level they exhibit the characteristics of periglomerular, external tufted, superficial short axon, horizontal and Van Gehuchten cells. It should be mentioned that another specific neuronal type was found in the inner third of the external plexiform layer, which is not described in other animals. These results revealed that a high number of intrinsic neuronal types of the olfactory bulb of the hedgehog display a strong VIP immunoreactivity.

Tyrosine hydroxylase immunoreactive neurons and fibers in the olfactory system of the hamster

AbstractTyrosine hydroxylaselike immunoreactivity is associated with several different classes of neurons in the main olfactory bulb of the hamster. Most of the tyrosine hydroxylaselike immunoreactive (THLI) neurons are located in the glomerular layer and in the outer two‐thirds of the external plexiform layer. The majority of THLI neurons in the glomerular layer have somal sizes and dendritic features which correspond to those of external tufted cells. A small population of THLI periglomerular cells also is present. The majority of THLI neurons in the external plexiform layer have the morphological characteristics of middle tufted cells. A small population of THLI neurons which appear to be Van Gehuchten cells is distributed throughout the external plexiform layer and in the mitral body layer. Small populations of THLI deep short‐axon cells are distributed throughout the mitral body, internal plexiform, and granule cell layers. Tyrosine hydroxylase‐positive fibers of central origin also are observed in the main olfactory bulb. They may originate from THLI neurons in the anterior olfactory nucleus, ventral hippocampal rudiment, dorsal peduncular cortex, septal and basal portions of the vertical limb and nucleus of the horizontal limb of the diagonal band, lateral and dorsal hypothalamus, ventral tegmental area and substantia nigra, dorsal and median raphe nuclei, and locus ceruleus. The frontal neocortex, infralimbic and anterior cingulate cortex, and medial amygdaloid nucleus also contain THLI neurons.In contrast to the widespread distribution of tyrosine hydroxylaselike immunoreactivity in the main olfactory bulb, substance P‐like immunoreactivity is restricted to external tufted cells and to centrifugal afferents which may originate in the dorsal and median raphe nuclei. Both types of immunoreactivity appear to be present in centrifugal afferents to the accessory olfactory bulb, but THLI neurons are extremely rare and no neurons with substance P‐like immunoreactivity have been observed in the accessory olfactory bulb. Intraventricular injections of colchicine which were expected to enhance the labeling of neuronal somata did not alter the relative incidences of labeling among the various classes of neurons in the olfactory bulbs.These findings provide immunocytochemical evidence that populations of superficially situated tufted cells in the main olfactory bulb are functionally distinct from the deeper‐lying output neurons and from output neurons in the accessory olfactory bulb, that populations of catecholami‐nergic neurons are present within several olfactory and related cortical structures in addition to the olfactory bulbs, that the medical septum‐diagonal band complex also contains catecholaminergic neurons, and that a substantial population of neurons in the dorsal raphe nucleus is capable of vatechol synthesis.

Cytoarchitecture of the extranuclear and commissural dendrites of hypoglossal nucleus neurons as revealed by conjugates of horseradish peroxidase with cholera toxin

The ipsilateral extranuclear dendrites of hypoglossal nucleus (HN) neurons of the rat, as revealed by conjugates of horseradish peroxidase (HRP) with cholera toxin (CTHRP), were distributed to four distinct regions: (i) to the reticular formation proper (“external dendrites” of Cajal); (ii) to the solitary nucleus and tract; (iii) to the medial longitudinal fasciculus; and (iv) to the nucleus raphe obscurus. The latter two distributions are described for the first time. They were best revealed by CTHRP; and less adequately by a wheat germ agglutinin HRP conjugate (WGHRP). They could not be demonstrated by free HRP. Furthermore, CTHRP best revealed the distribution of commissural dendrites of HN neurons, the tuftlike structures at the termination of some external dendrites of Cajal, and the few dorsal protoplasmic commissural dendrites coursing dorsal to the central canal and to the contralateral solitary nucleus and the area postrema. To further clarify the distribution of the commissural dendrites of the HN, cholera toxin HRP was injected into the tongue of rats after one hypoglossal nerve had been severed. We found that the retrogradely labeled commissural dendrites crossed the midline horizontally to enter the contralateral HN and the solitary nucleus and tract as well as the reticular formation and the medial longitudinal fasciculus. The method greatly expanded our knowledge of the course and terminations of the commissural dendrites of the “protoplasmic commissure” of Van Gehuchten. We conclude that the cholera toxin HRP conjugate was a sensitive probe for the demonstration of the dendritic arborization of retrogradely labeled neurons.

Laminar distributions of interneurons in the main olfactory bulb of the adult hamster

The laminar distributions of intemeurons in the hamster olfactory bulb were studied with rapid Golgi techniques. Eight morphologically distinct classes of intemeurons were characterized according to their somal locations and their dendritic and axonal properties. Two of these classes, Blanes and Golgi cells, had somata restricted to the deeper layers of the bulb and were not observed more superficially than the mitral body layer (MBL). Their dendrites and axons were predominantly situated within the granule cell layer (GRL) and internal plexiform layer (IPL) but occassionally could be traced as superficially as the deeper portion of the external plexiform layer (EPL). Neither their dendrites nor their axons were oriented consistently with respect to the layers of the bulb. Blanes cells had numerous dendritic spines whereas Golgi cells were relatively spine-poor. Two other classes had somata that were restricted to the IPL and MBL, and had dendrites that exhibited clear orientations with respect to these layers. One class, horizontal cells, had dendrites that ran tangentially within the IPL and MBL. The other class, Cajal cells, had radially oriented dendrites that extended peripherally into the superficial region of the EPL and centrally for greater distances into the GRL. Both classes had axons that projected superficially into the EPL. The granule cells in our material were similar to those described in other species. The sixth class of intemeurons was designated as Van Gehuchten cells. The somata of Van Gehuchten cells were restricted to the EPL and MBL. Their processes branched elaborately within the EPL and MBL but were not oriented consistently with respect to these layers. It is unclear from our material whether these cells bear axons or whether they are amacrine intemeurons. Another class, superficial short axon cells, had somata that were predominantly located at the boundary between the EPL and the glomerular layer (GL) but could also be found throughout the periglomerular region and the superficial half of the EPL. These cells had dendritic and axonal processes that extended predominantly into the GL and appeared to branch around and between individual glomeruli. The eighth class, periglomerular cells, had somata located throughout the GL. Most of these cells gave rise to one dendritic trunk that arborized within a single glomerulus. Occassionally a second, less elaborate dendritic process emerged from the main trunk or from the soma and extended into the periglomerular space or encroached upon an adjacent glomerulus. However, we did not find any periglomerular cells with extensive dendritic arbors in more than one glomerulus. These distributions are discussed in relation to the notion that olfactory bulb interneurons may be assigned to two functional groups associated with two distinct levels of integration.

Facial, vagal and glossopharyngeal nerves in the cat. Afferent connections.

The observations contained in this report stem from a study of pain afferent nerve fibers from craniofacial and cervical regions, particularly in relation to referred-pain syndromes and atypical neuralgias. Early studies by Cajal and van Gehuchten, among others, provided much of the basic information on the organization of the visceral afferent fibers of the facial (VII), glossopharyngeal (IX), and vagal (X) nerves. Subsequent investigators * have traced these afferent fibers in various species, including man. Despite these detailed and careful reports, numerous aspects of the connections of the afferent fibers remain undetermined. In particular, the site of termination of fibers mediating pain has been inferred mainly from surgical and clinical studies, but never established anatomically; tactile connections have been suggested on rather vague grounds, and deep sensibility connections have remained entirely unknown. Material and Methods Twenty-three adult cats weighing between 4 and 9 lb. each were used; the results in 17

Some aspects of Sherrington’s contribution to neurophysiology

Since this year we are celebrating the centenary of Sherrington’s birth, it is fitting that we should try to understand and appreciate the significance of his life. Doubtless we still live too close to him for final evaluation, if that ever can be made, but this is the occasion for an appraisal by those who knew him and who are happy to be called his pupils. In the history of physiology there is one achievement that ranks above all others—the discovery of the circulation by Harvey. That discovery gave the foundation on which the physiology of the circulation could be built as a secure and ever-growing structure. It has been claimed that Sherrington’s achievement has been to construct the secure foundations for the physiology of the central nervous system, and even that The integrative action of the nervous system has had an influence comparable with that of De motu cordis . On account of its great complexity it is easy to understand that the central nervous system had to wait for almost three hundred years longer than the circulation before the foundation of understanding could be built. In fact Sherrington’s work could not have been done earlier. Descartes, Magendie, and Bell, for example, suffered from an insurmountable handicap, because it is only in terms of the fine structure that the working of the nervous system can be understood. As so often happens in outstanding human achievements, the young Sherrington had the good fortune to live just when the great neuro-histologists were making their fundamental contributions and he was no mean neuro-histologist himself. Sherrington saw clearly the enormous significance of the neurone theory of His, Forel, Cajal and van Gehuchten, so that all his physiological thinking was conceived in terms of the anatomical independence of the nerve cells or neurones. Hitherto the nervous system had been conceived as a complex network of fine nerve branches which freely anastomosed with each other.

TRANSTENTORIAL HERNIATION OF THE BRAIN STEM

While death due to medullary compression associated with herniation of the cerebellar tonsils has long been known, relatively little attention has been paid to the sequela of compression of the brain stem caused by herniation of the stem through the tentorial opening. In 1920 Meyer called attention to medial displacement and herniation of the hippocampal gyrus into the tentorial incisura in cases of space-consuming intracranial lesions. The subject was later elaborated by van Gehuchten,¹Jefferson,²Reid and Cone,³Moore and Stern⁴and Smyth and Henderson.⁵All these contributors have amply demonstrated that space-consuming lesions may cause appreciable herniation of the hippocampal gyrus of the temporal lobe into the potential space that lies directly above and between the free edges of the tentorium cerebelli and the brain stem. The same type of herniation has been recently observed by Schwarz and Rosner⁶in 100 cases of

HISTOLOGIC STUDIES OF THE BRAIN FOLLOWING HEAD TRAUMA

For the surgeon faced with the practical problem of treating injuries of the head there remain at least two great unsolved problems. These are the vascular alterations related to edema and hemorrhage within the brain substance and the disturbances in circulation of the cerebrospinal fluid. From the field of intracranial tumor surgery have come most of the significant contributions to the present, somewhat inadequate, understanding of the latter problem. The most recent additions to knowledge have concerned herniation of the uncus of the temporal lobe through the incisural notch. The subject has been elaborated on in a series of papers, among which may be cited those of Meyer, 1 van Gehuchten, 2 Jefferson, 3 Reid and Cone, 4 Moore and Stern, 5 Smyth and Henderson 6 and Schwarz and Rosner. 7 Some of these authors have noted the same phenomenon in association with epidural and subdural hematomas. Thus, it now

DISPLACEMENT AND HERNIATION OF THE HIPPOCAMPAL GYRUS THROUGH THE INCISURA TENTORII

It has long been recognized that a mass lesion within the cranial cavity often produces disturbances of function which cannot be ascribed to the actual site of the growth. 1 One of the causes of distant or false localizing signs of an expanding intracranial lesion is the shift of the brain substance to produce herniations about certain partially fixed, extracerebral structures and into certain potential spaces within the skull cavity. 2 Thus, a representative herniation, the cerebellar pressure has been understood to have considerable clinical significance ever since it was described by Alquier, in 1905. 3 Similarly, after Adolf Meyer's description and illustration of herniation of the hippocampal structures into the incisura tentorii, 4 it has become evident that this dislocation of cerebral substance, called by van Gehuchten 5 the temporal pressure cone, is a consistent producer of secondary functional derangements. Evidence has accumulated to show that such a

Comparative Methods of Diagnosis of Rabies in Animals

NEGRI announced his microscopic test for rabies in 1903 which has since been generally followed in routine diagnostic work. A considerable amount of investigation concerning the pathological changes in the central nervous system had already been published. As early as 1892 Babes' described his rabic tubercles.. Ganglionic changes occurring in the disease were described by van Gehuchten and Nelis,2 and McCarthy and Ravenel.3 Following the announcement of Negri's discovery earlier microscopic methods of diagnosis were gradually succeeded by the Negri body test. It is known that Negri bodies are not always demonstrable in the brains of rabid animals. Joseph Koch 4 states that 10 to 12 per cent of the brains which are positive on animal inoculation will fail to show Negri bodies when the customary method of examination is employed. This percentage of error, he claims, would be reduced if impressions or smears were taken from ganglion cells and various parts of the brain instead of from the Ammon's

VESTIBULO-OCULAR REFLEX ARC

THE PROBLEM The actual anatomic foundations of the concept of the reflex arc were laid by Ramon y Cajal between 1887 and 1892, when he carried out a systematic study of the spinal cord with the method of Golgi. Cajal's findings were soon confirmed by the best neuro-anatomists (van Gehuchten, von Lenhossek, Held, Retzius, von Kolliker and others).1A short time later, when Cajal and van Gehuchten developed the concept of axonal polarization, the elementary reflex arc acquired a more general significance; it became the expression of the fundamental plan of structure and function of the nervous system. Figure 1 reproduces the original diagram of Cajal, showing the reflex arc composed of the afferent sensory neuron, the efferent motoneuron and a connecting link that may either be only a collateral from the posterior root or also include one or more intercalated (internuncial) neurons. When the internuncial neurons lie outside