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PubMed1982

Significance of glycosidases in myelin-lipid metabolism. I. Studies in diencephalon of fresh water turtle (Lissemys punctata granosa).

The contribution deals with functional significance of glycosidases in myelin-lipid metabolism. Glycosidases (beta-galactosidase, beta-glucosidase and beta-glucuronidase), in diencephalon of turtle, are observed in the myelinated fibers of tractus opticus and dorsal and ventral peduncles of lateral fore-brain bundles. Further, phospholipids preparations of this area have represented mirror image of glycosidases, suggesting role of these enzymes in its metabolism. Glycolipids concentration in myelin is also very high, further, suggesting the role of glycosidases in their degradation. The enzymatic activity in cellular elements is quite poor and same is also true with phospholipids.

Animals↗
PubMed1978

[Embryonal development of the brain of the shark Scyliorhinus canicula (L.). I. Formation of the shape of the brain, the migration mode and phase and the structure of the diencephalon].

Brain structure of the shark Scyliorhinus canicula has been studied on the basis of a series of embryonic stages. The incubation time was 157 days in average (under constant conditions of 15 centigrades and density of 1.026). 1. The first predominant characters of the external brain shape are the optic tectum, cerebellum, telencephali hemispheres and oculomotor root. In addition, the brain axis is characterized by new flexures in the cerebellar and prosencephalic level. A nuchal flexure in absent. 2. The ontogenetic pattern of the matrix layer differs in different brain parts. Generally, ventral columns develop earlier than dorsal ones. Matrix development and cell proliferation occur especially late in the cerebellum. For the most part the results agree with findings by KAHLE (1951) concerning the human brain. The telencephalon is an exception and shows a developmental retardation, while a regular development is observed in Scyliorhinus. 3. The hypothalamus overlaps the other regions of the diencephalon. The ventral thalamus is small, a dorsal thalamus is not observed. The pretectal region is remarkably differentiated and contains a rich set of nuclei. 4. The epithalamus is asymmetrical; a phenomenon that occurs after hatch. The left habenula is distinctly larger than the right-one.

Animals↗
PubMed1978

Ascending brain stem pathways to the diencephalon and limbic regions: a light and electron microscopic study in the rat.

Total and partial meso-diencephalic transections and lesions of the central gray matter were performed to trace with the Fink--Heimer silver impregnation method the ascending brain stem pathways to the forebrain. Most of these pathways are located near the midline at the level of their entry into the diencephalon. Fibers directed to the hypothalamus either leave the central gray matter and proceed rostralwards in the periventricular tissue layers, or, after traversing the ventral tegmental area, join the medial forebrain bundle. It can be established on the basis of electron microscopical studies that the ascending brain stem pathways project to all hypothalamic nuclei and to the median eminence.

Animals↗
PubMed1976

The diencephalon of the vervet monkey (Cercopithecus aethiops). Part II: epithalamus, subthalamus and hypothalamus.

The nuclear configuration and topography of the epithalamus, subthalamus and hypothalamus of the vervet monkey (Cercopithecus aethiops) are described and compared with those of other primates, particularly the macaque monkey. The epithalamus does not show any striking structural differences, except some architectonic differentiation in the lateral habenular nucleus. The subthalamus is a phylogenetically stable structure throughout the primate scale; it does not show any significant changes, except that it extends less rostrally and that the nuclei entopeduncularis and peripeduncularis are much smaller and less well defined in the vervet monkey than those in the diencephalon of lower primates. The nucleus subthalamicus and the fields of Forel, though small in size, are comparatively well developed; the zona incerta appears to be differentiated cytoarchitectonically into two parts. The hypothalamus is divided morphologically into four regions--the preoptic, supraoptic, infundibular and mamillary regions. Although the hypothalamus of the vervet monkey is topographically identifiable with those of other primates, there are cyto- and myeloarchitectonic differences to be found in certain hypothalamic nuclei and areas. The preoptic region is small and poorly delimited from the parolfactory region antierorly and the supraoptic region posteriorly. The nucleus paraventricularis is large and well differentiated into secretory and non-secretory portions; the nucleus supraopticus does not show cellular separation into dorsolateral and ventromedial parts as clearly as they are in other primates. The nucleus dorsomedialis is not as well defined as the nucleus ventromedialis like it is in other primates. The nucleus tuberalis lateralis is comparably small, and is not split into several cellular groups as it is in higher primates. The posterior hypothalamic area is morphologically the best definable of the hypothalamic areas. The mamillary region is developmentally advanced, and very well differentiated into medial, lateral and intercalated nuclei.

Animals↗
PubMed1995

Calbindin D-28K-immunoreactivity in the cat diencephalon: an immunocytochemical study.

The distribution of calbindin D-28k-immunoreactive fibers and cell bodies in the cat diencephalon has been analyzed by using the avidin-biotin immunoperoxidase technique. The thalamus showed a higher density of immunoreactive cell bodies than the hypothalamus. A high density of both immunoreactive perikarya and fibers was observed in the nuclei pulvinar, geniculatum mediale and laterale, lateralis posterior and dorsalis, habenularis lateralis and medialis, posterior, subparafascicularis, submedius, centralis medialis, medialis dorsalis, ventralis postero-medialis and postero-lateralis, reticularis, centralis lateralis, rhomboidens, paracentralis, ventralis lateralis, anterior and medialis, reuniens, anterior ventralis and medialis, hypothalamus posterior, corpus mamillare, area hypothalamica dorsalis and in the hypothalami ventromedialis. Moreover, a high density of fibers containing calbindin and a moderate/low density of immunoreactive cell bodies was found in the nuclei periventricularis anterior, parataenialis, hypothalamus lateralis, mamillaris lateralis, filiformis, periventricularis hypothalami, hypothalamus anterior and in the suprachiasmaticus.

Animals↗
PubMed1995

Cavernous angioma of the diencephalon.

A case of cavernous angioma of the diencephalon presenting with subarachnoid hemorrhage in a 19 years old woman is reported. Pertinent literature is reviewed. Clinical data, Computerized Tomography (CT) and pre and post operative Magnetic Resonance (MR) imaging are presented and discussed. The problems of diagnosis and treatment of cavernous angiomas localized in critical areas of the brain are also discussed.

Adult↗
PubMed1994

Chronic alcoholics have substantial glial pathology in the forebrain and diencephalon.

We have analyzed glial changes in forebrain and diencephalic regions in 19 alcoholics with different histories of chronic alcohol consumption and related medical complications including Wernicke's encephalopathy and alcoholic liver disease. Cases with postmortem evidence of hepatic encephalopathy were excluded. Two of the alcoholic patients had ceased drinking for several years prior to death. Brains were obtained postmortem and fixed in formalin. Serial 50 microns sections of the forebrain and diencephalon at 750 microns intervals were stained with standard histochemical stains (haematoxylin and eosin, luxol fast blue, cresyl violet and silver), as well as immunohistochemically for glial fibrillary acidic protein (GFAP). In control tissue, GFAP-positive astrocytes were intimately associated with ependymal, pial, and vascular surfaces. In alcoholic cases, the morphology of these cells was markedly changed showing enlargement of the cell bodies and beading of the cellular processes. In contrast to controls, GFAP-positive astrocytes were seen within and surrounding clusters of magnocellular neurons in the basal forebrain and hypothalamus. In thiamine-deficient alcoholics, glial scarring in the vicinity of the large branches of the cerebral arteries disrupted the normal forebrain architecture. A patchy loss of GFAP immunostaining was seen in most severe cases. A remarkable number of corpora amylacea also rimmed blood vessels, pial and ependymal surfaces in all alcoholics compared to controls. The beaded fibers were seen in alcoholics drinking at the time of death as well as in those who had ceased drinking alcohol several years prior to death. These results indicate that chronic alcoholics have prominent glial changes which persist despite the cessation of alcohol consumption and are not exclusive to alcoholics with liver pathology.

Adult↗
PubMed1998

Histaminergic neurons in the sheep diencephalon.

The distribution of histaminergic neurons in the sheep brain was studied by immunohistochemistry by using antibodies raised against histamine. For the first time in this species, the presence of histamine-immunoreactive neurons was described in the caudal diencephalon, around the mammillary bodies, and in the tuberomammillary area. The general pattern of distribution of these neurons was similar to that described previously in other species, i.e., rodents and humans. The distribution in the five neuronal groups described in rodents was not easy to demonstrate in sheep, because the boundaries between each group were not clear. The labeled neurons appeared to form a continuous cell system, as in humans. Numerous histamine-immunoreactive mast cells were found in the habenula and the thalamus. Histamine-immunoreactive fibers were found in almost all of the structures studied. The highest density of fibers was seen in the tuberomammillary area, from which dense bundles of fibers ran rostrally and dorsally along the third ventricle in a parasagittal plane. Numerous immunostained fibers were found close to the wall of the ventricles; some of them appeared to reach the cerebrospinal fluid through the ependymal cell layer. Some fibers were also observed in the optic tract, and the lowest density was found in the supraoptic and paraventricular nuclei. These results should be useful for developing further physiological studies on the role of histaminergic neuronal systems in sheep.

Animals↗
PubMed1976

Histological and histochemical observations on the neurosecretory cells in the diencephalon of Chthonerpeton indistinctum and Ichthyophis paucisulcus (Gymnophiona, Amphibia).

In the diencephalon of two species of Gymnophiona (Amphibia) two neurosecretory nuclei were examined with histological (Alcian Blue, Aldehyde Fuchsin, Brookes Trichrome stain) and enzyme histochemical techniques (acid phosphatase, alpha-naphthyl acetate esterase, acetylcholinesterase (AChE)). In the preoptic nucleus two categories of secretory neurons were distinguished: large and medium sized neurons. The perikarya of both cell types contain very little neurosecretory material. The Alcian Blue method stained the medium sized neurons faintly but selectively. The tractus praeopticohypophyseus is marked by the presence of Herring bodies, which, however, are relatively scarce. The neurohypophysis, in contrast, contains large amounts of neurosecretory material. Both cell types of the preoptic nucleus are characterized by their very strong AChE and alpha-naphthylacetate esterase activity. The AChE also marks the tractus praeoptico-hypophyseus. In the large neurons acid phosphatase is present around the nucleus; in the medium sized neurons this enzyme is concentrated close to the origin of the axon. In the dorso-caudal hypothalamus a small group of neurons is stained with Alcian-Blue. These neurons, which also contain AChE, are located immediately under the ependyma which seems to be specialized in this region.

Acetylcholinesterase↗
PubMed2006

Disseminated pilocytic astrocytoma involving brain stem and diencephalon: a history of atypical eating disorder and diagnostic delay.

The association of weight loss and pediatric brain tumors that affect the diencephalon or brain stem with weight loss is a recognized, but not fully understood phenomenon. Tumors located in the hypothalamic region may induce the diencephalic syndrome (DS), which is characterized by profound emaciation with almost complete loss of subcutaneous fatty tissue. Tumors that compress or infiltrate the brain stem rarely cause both psychological disturbance and emaciation. The clinical presentation may be different, depending on the location of the lesion and age of the patient. In this report we present an unusual case of severe emaciation in a 4(9)/(12)-year-old girl with a juvenile pilocytic astrocytoma of the hypothalamic region and brain stem with neuroaxis dissemination. This case illustrates the importance of considering intracranial mass-lesions in the differential diagnosis of weight loss, psychological disturbance and atypical eating disorder. We discuss the importance of tumor multifocality and the role of patient age in the clinical presentation with reference to the literature.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1985

Dual estradiol action in diencephalon and the regulation of sociosexual behavior in female golden hamsters.

Previously, we found that single implants of estradiol (E2) placed in the ventromedial hypothalamus (VMH) but not the anterior hypothalamus (AH) facilitated precopulatory, i.e. vaginal scent marking, and copulatory, i.e. lordosis, behavior following progesterone administration. However, the duration of lordosis was markedly attenuated in comparison to the duration shown by intact cycling females. This study was designed to examine whether dual implantation of E2 in the diencephalon would facilitate patterns of precopulatory and copulatory behaviors similar to those shown by intact cycling females. One E2 implant was placed in either the medial preoptic area (MPO) or AH and a second E2 implant was placed in the VMH. Control females were tested following E2 application at only the MPO or AH region in conjunction with a cholesterol implant in the VMH. An additional control group was tested with females implanted with cholesterol at both MPO-AH regions and the VMH. During a 2-day postimplantation test period, vaginal marking scores were elevated for both single and dual E2 implanted females and agonistic response patterns toward males declined significantly. In addition, a significant inverse relationship was found between the number of vaginal marks and bites exhibited by females with single E2 implants in the MPO, whereas these two response patterns were positively correlated in females with E2 stimulation occurring only in the AH region. No significant relationship was found between vaginal marking and biting attack for females receiving dual E2 stimulation. Systemic progesterone administration on the third postimplantation day facilitated sexual receptivity in the majority of females with dual E2 implants (greater than 90%). These receptive females displayed lordotic responsiveness that closely matches the full display of sexual receptivity shown by intact cycling females. In contrast, only one female with a single E2 implant in the AH region showed sexual responsiveness. The results demonstrate that: precopulatory vaginal marking and biting attack are mediated by E2 action in the MPO and AH but in a different manner; additional action of E2 in the VMH diminishes the distinctive precopulatory behavioral effects of E2 in the MPO and AH suggesting an influential role of the VMH in regulating sociosexual activities; and E2 action in either the MPO or AH region in conjunction with E2 action in the VMH may be necessary in order to facilitate the species-typical display of lordotic responsiveness.

Aggression↗
PubMed1988

Projections of the intermediate subdivision of the central amygdaloid nucleus to the bed nucleus of the stria terminalis and medial diencephalon.

The forebrain projections of the intermediate subdivision of the central amygdaloid nucleus (CI) were studied using the horseradish peroxidase (HRP) retrograde transport technique. Injections of wheatgerm agglutinin-conjugated HRP into the bed nucleus of the stria terminalis and medial thalamus resulted in moderate retrograde labeling in CI while injections into the medial hypothalamus produced very dense cell labeling in CI. The dorsal hypothalamic area appears to be the main target of the efferents to the hypothalamus. Although previous histochemical studies have suggested that CI may be part of the lateral subdivision of the central nucleus (CL), the projection of CI to the medial diencephalon clearly distinguishes CI from CL.

Amygdala↗
PubMedDate not supplied

Responses evoked by stimulation of points in the diencephalon of unrestrained rabbits.

Behavioural responses were obtained from unanaesthetized rabbits by stimulating the diencephalon through implanted electrodes (10--250 micro A, 1 msec, 60 Hz). Mild arousal and related effects were evoked from widespread sites between stereotaxic planes P 1.5--P 4.5 and 0.1--3.5 mm from the midline. Stimulation readily evoked vigorous running responses, together with other responses suggestive of agitation with escape and concealment behaviour, at sites in the hypothalamus within 2 mm of the midline near or just caudal to the mammillothalamic tracts. Signs of rage or aggression were infrequently seen. When the centre of this hypothalamic zone was stimulated after re-anaesthetizing the animals, bradycardia was obtained. The results are interpreted as suggesting that stimulation in this area, which is known to evoke cardiovascular responses different from the carnivore, also evokes a modified form of "Defence Reaction" appropriate to a species that is preyed upon.

Animals↗
PubMed1980

The morphology of the diencephalon in the Prosimii. II. The Lemuroidea and Lorisoidea. Part II. Epithalamus, subthalamus and hypothalamus.

This study (Part II) deals with the comparative structure of the epithalamus, subthalamus and hypothalamus. The same prosimian species used in the study of the thalamus and metathalamus (Part I) are used here. The epithalamus does not show any remarkable change in the phylogeny of the prosimian diencephalon. In the subthalamus, the nucleus subthalamicus enlarges progressively in size, and shows a very close relationship to the zona incerta, the fields of Forel and the pregeniculate body. The zona incerta is observed to consist of two parts the ventral part relating to the nucleus subthalamicus and the dorsal part ot the nucleus reticularis. The fields of Forel is well differentiated into fields H1 and H2. The hypothalamus is described here having four regions--preoptic, suraoptic, infundibular and mamillary. The preoptic and supraoptic regions appear to be indivisible in all prosimian species, for the constituent nuclei of both regions extend rostrally and caudally in the anterior part of the hypothalamus. The nucleus supraopticus is evidently complicated in structure, as it appears not only to have two separate parts, but also an isthmus that connects these parts. This interlinking strand of cells is termed not the nucleus supraopticus diffuses but the nucleus/area commissuralis postopticus. The nucleus paraventricularis is a massive nucleus, and appears to have a non-neurosecretory part and a neurosecretory part. An interesting feature has been observed in certain prisimian species such as Galago demidovii, Lepilemur and Loris gracilis, the nucleus paraventricularis accessorius which may be regarded as an erratic derivative of either nucleus paraventricularis or nucleus supraopticus. The nucleus tuberalis lateralis makes its first definitive appearance in the Prosimii. The nucleus ventromedialis hypothalami appears to be larger and more clearly defined than the nucleus dorsomedialis hypothalami. From the latter nucleus, a cellular condensation has been observed to stretch lateralwards--nucleus dorsolateralis hypothalami. The hypothalamic areas--anterior, dorsal, lateral and posterior--are not very much different among the prosimian species, although the anterior and posterior hypothalamic areas appear to have more attributes of a nucleus than an area. The mamillary region is very well developed in all prosimian species. The medial mamillary nucleus is clearly divided into several parts. The nucleus mamillaris lateralis is poorly developed, but can be identified lying between the lateral part of the medial mamillary nucleus and the nucleus intercalatus. In regard to the latter nucleus, there is some topographical confusion, but the nucleus intercalatus is easily identified as the bed nucleus of the supramamillary commissure.

Animals↗
PubMed1976

The diencephalon of the vervet monkey (Cercopithecus aethiops). Part I: thalamus and metathalamus.

The diencephalon of the vervet monkey (Cercopithecus aethiops) is described and compared with that of other primates, particularly the macaque monkey (Macaca mulatta). In the vervet monkey, the thalamus is divided into six nuclear groups: anterior, midline, medial, dorsolateral, ventrolateral and posterior. The anterior nuclear group shows a regressive nucleus anterodorsalis and a poorly defined demarcation between the nuclei anteromedialis and anteroventralis. There is a large interthalamic adhesion in which the ventral region containing nuclei centralis medialis, interventralis and reuniens, shows more regression than the dorsal region consisting of nuclei parataenialis and paraventralis. As the nucleus medialis ventralis is not present, the nucleus medialis dorsalis is described as the nucleus medialis; this is clearly differentiated into three parts, each part showing different cytological and architectonic features. The nucleus centrum medianum is larger and better developed than that of lower primates but is not entirely demarcated from the nucleus parafascicularis. The pulvinar is an enormous outgrowth from the dorsolateral thalamic nuclei. The ventrolateral thalamic nuclei are well differentiated from one another: a distinct nucleus ventralis dorsomedialis is present and appears to possess definite topographical and cytological differences from those of the other ventrolateral nuclei. The nucleus ventralis posteromedialis is further differentiated into a magno- and a parvocellular part. The nucleus ventralis posteroinferioris is a distinct entity. The lateral geniculate body shows a definite differentiation into two nuclei: pregeniculate and lateral geniculate nuclei. The lateral geniculate nucleus is a six-layered structure which is of the inverted type; it has undergone a lateral rotation through an anteroposterior axis from a dorsal position in the prosimian thalamus to its present ventral position in the higher primate thalamus. The medial geniculate body is not laminated as is the lateral geniculate nucleus; it consists of a small dorsomedial magnocellular and a large ventrolateral parvocellular part.

Animals↗