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At least 379 records · Page 21Linked to original sources
PubMed1993

The diencephalon of the Pacific herring, Clupea harengus: cytoarchitectonic analysis.

The cytoarchitecture of nuclei in the preoptic area, ventral thalamus, dorsal thalamus, epithalamus, hypothalamus, posterior tuberculum, synencephalon, and pretectum and the accessory optic nuclei was analyzed in the clupeomorph teleost, Clupea harengus. Plesiomorphic (evolutionarily primitive) and apomorphic (evolutionarily derived) features of nuclei were identified by cladistic analysis. Plesiomorphic features include the cytoarchitectonic organization of most of the preoptic nuclei, the somewhat scattered cells of nucleus ventrolateralis, the compact, oval shape of nucleus intermedius, the presence of dorsoventrally oriented laminae in the central posterior nucleus, and most features of the hypothalamic nuclei. Also plesiomorphic are the presence of a thick, prominent paraventricular organ, a nucleus of the paraventricular organ, a nucleus tuberis posterior, and a preglomerular complex in which the boundaries between multiple nuclei are relatively difficult to distinguish. Additionally, the cytoarchitecture of the three synencephalic nuclei present in Clupea, the presence of small cells in nucleus pretectalis superficialis pars parvicellularis and of larger, scattered cells in nucleus pretectalis superficialis pars magnocellularis, the presence of large cells in the dorsal accessory optic nucleus that form a rostrocaudally oriented column, and the feature of a small, cell-sparse ventral accessory optic nucleus are plesiomorphic. Apomorphic features include the presence of a single, large, circular lamina that surrounds a central neuropil in all but the most caudal part of nucleus anterior, a lack of bilateral asymmetry in the habenular nuclei, the relatively small size of the periventricular nucleus of the posterior tuberculum, the presence of two, distinguishable caudomedial nuclei in the posterior tuberculum, elongation and folding of the neuropil of nucleus pretectalis superficialis pars parvicellularis, and the relatively large size of nucleus pretectalis superficialis pars magnocellularis and the posterior pretectal nucleus.

Animals↗
PubMed1995

Periventricular morphology in the diencephalon of antarctic notothenioid teleosts.

We have examined the subependymal region of the diencephalic third ventricle in notothenioid perciforms and report a pattern of neuropil expansions that appears to be phyletically derived for notothenioids and their outgroups but that is otherwise unique among vertebrates. We recognize five types of expansions based on their composition (from less dense neuropil to sacs) and width or protrusion into the third ventricle. In the species with the most elaborate morphology, Trematomus bernacchii, bilateral subependymal expansions fuse along the midline to form a single sac within the ventricular cavity. The extent of these expansions loosely corresponds with phyletic position but also (and perhaps more importantly) is correlated with the habitation of cold water (r2 = 0.48; P = 0.012). Furthermore, subependymal expansion type is positively correlated with the maximum size of the soma of neurons in two hypothalamic nuclei, the preopticus magnocellularis (r2 = 0.54; P = 0.006) and the lateralis tuberis (r2 = 0.40; P = 0.038). These nuclei project to the pituitary and contain cerebrospinal fluid-contacting neurons. In considering the functional consequences of this morphology, we cannot dismiss the possibility that these structures form a specialized enteroceptive system tied to the monitoring of cerebrospinal and extracellular fluid components, including antifreeze glycopeptides and inorganic ions.

Acclimatization↗
PubMed2004

Msx1 disruption leads to diencephalon defects and hydrocephalus.

We have analyzed the expression of the Msx1 gene in the developing mouse brain and examined the brain phenotype in homozygotes. Msx1 is expressed in every cerebral vesicle throughout development, particularly in neuroepithelia, such as those of the fimbria and the medulla. Timing analysis suggests that Msx1(nLacZ) cells delaminate and migrate radially from these epithelia, mainly at embryonic days 14-16, while immunohistochemistry studies reveal that some of the beta-galactosidase migrating cells are oligodendrocytes or astrocytes. Our results suggest that the Msx1 neuroepithelia of fimbria and medulla may be a source of glial precursors. The Msx1 mutants display severe hydrocephalus at birth, while the subcommissural organ, the habenula, and the posterior commissure fail to develop correctly. No label was detected in the mutant subcommissural organ using a specific antibody against Reissner's fiber. Besides, the fasciculus retroflexus deviates close to the subcommissural organ, while the paraventricular thalamic nucleus shows histological disorganization. Our results implicate the Msx1 gene in the differentiation of the subcommissural organ cells and posterior commissure and that Msx1 protein may play a role in the pathfinding and bundling of the fasciculus retroflexus and in the structural arrangement of the paraventricular thalamic nucleus.

Animals↗
PubMed1993

Effects of changes in gonadal hormones on the amount of aromatase messenger RNA in mouse brain diencephalon.

Aromatase in brain is known to play a crucial role in development and maintenance of androgen dependent sexual behavior of males. Biochemical studies have shown that the aromatase activity in brain is influenced by androgen. In this study, we measured the aromatase mRNA content of mouse brain quantitatively to gain a deeper insight into this phenomenon. We found that in the diencephalic area it is sexually dimorphic, as reported for aromatase activity. The amount of aromatase mRNA in this area in males was 150% higher than that in females and decreased to the level in females after castration. The content of aromatase mRNA in castrated males was elevated by 2-fold by injection of testosterone and restored to the level observed in intact males. Injection of testosterone also affected the level of aromatase mRNA in normal mice of both sexes, though to lesser extent. On the contrary, injection of estrogen decreased the amount of aromatase mRNA in gonadectomized mice of both sexes. These results show that transcriptional control of the aromatase gene is involved in the mechanism of testosterone to affect sexual behavior.

Animals↗
PubMed1994

Radiosurgical treatment of gliomas of the diencephalon.

The results of Leksell Gamma Knife treatment of diencephalic gliomas are presented. Eight tumours in seven patients form the basis of this report. 7 patients, 4 males and 3 females. The age range was 7.5 to 33 years with a mean of 18 years. Mean follow-up was 21 +/- 12 months. In 4 patients the tumour had been reduced in volume by an open internal decompression procedure. The location of the tumour will determine the risks of treatment. With anterior lesions there is risk of endocrinological and visual pathway damage. With a pineal region lesion there is a risk of diplopia. In this series no tumour has increased in volume. Four have decreased and one has disappeared. Two patients suffered temporary diplopia. No visual disturbance has been observed to date. No hypothalamic disturbance has been observed yet. These tumours are dangerous not so much because of their biological nature as because of their location. However, the biological nature of the tumours, with the close concordance between the radiological and actual extent make them appropriate targets for radiosurgery as a primary treatment. The present study gives preliminary support to this line of treatment.

Adolescent↗
PubMed1991

Observations on the fate of nucleus superficialis magnocellularis of Rendahl in the avian diencephalon, bearing on the organization and nomenclature of neighboring retinorecipient nuclei.

The cytoarchitectonic development of an. superficialis magnocellularis (dorsal thalamus, posterior parencephalon) was studied from 3 days of incubation up to the mature state after hatching in the chick. A hypothesis of Kuhlenbeck (1937) on a partial transformation or contribution of SM cells into a different neighbouring griseum was tested, in the wider context of divergent interpretations of diencephalic development either within Herrick's (1910) longitudinal columnar theory, or within a modified neuromeric conception (Puelles et al. 1987 a). Nucleus SM develops early within the alar region of the posterior parencephalon, forming an outer mantle stratum over the main telencephalopetal thalamic inner cell mass. Thymidine-labeling data pinpoint its generation period mainly between 3 and 4.5 days of incubation. Throughout its subsequent development, SM remains within the primary interneuromeric limits that separate it from ventral thalamus and pretectum. After 8 days of incubation, SM subdivides into superficial (compact) and deep (disperse) sublaminae. The superficial one becomes much compressed between n. geniculatus ventralis and n. synencephali superficialis. Some of its cells migrate interstitially into the optic tract (12-16 days in ovo) and later disappear. The corresponding mature remnant was called n. interstitialis tractus opticus (ITO). The deep sublamina of SM forms a cap around n. rotundus. It becomes increasingly dispersed due to many passing fibers, and may be recognized in the mature brain as an area perirotundica (ApR). Clarification of the fate of embryonic SM bears on the confused terminology for various visual diencephalic nuclei. It is argued that the terms n. geniculatus dorsalis p. principalis and p. intercalaris, n. superficialis magnocellularis (in its wrong usage), n. lamminaris precommissuralis, n. lentiformis mesencephali p. medialis, p. parvocellularis and p. magnocellularis should be considered obsolete, on various embryological and hodologic grounds. An embryologically consistent terminology is proposed.

Animals↗
PubMed1984

Topography of retinal axons in the diencephalon of goldfish.

The projections of horseradish peroxidase-filled axons from each quadrant of the retina were studied to determine whether retinal projections of goldfish are topographically organized in diencephalic target nuclei. A distinct topography of the dorsal, nasal, ventral and temporal retina exists in the lateral geniculate nucleus and in the dorsolateral optic nucleus of the thalamus. The projections of retinal quadrants show minimal spatial overlap in each of these nuclei. The suprachiasmatic nucleus of the hypothalamus is extensively innervated by ventral retinal fibers, whereas the nucleus is sparsely innervated by fibers from the other three retinal quadrants. A rudimentary topography also exists in the pretectum where the dorsal pretectal area receives projections primarily from the ventral retina and the ventral pretectal area receives projections mostly from the dorsal retina. These data show that retinal projections to some diencephalic nuclei are topographically organized.

Afferent Pathways↗
PubMed1984

The interrelations between cell groups in the caudal diencephalon of the rat projecting to the striatum and to the medulla oblongata.

In order to investigate the topographical relationships between the caudal diencephalic cells of origin of ascending and descending projections in the rat, one fluorescent retrograde tracer was injected into the striatum and another into the medulla oblongata. The medullary injections were mainly centered in the inferior olive. Cells labeled from the striatal injections densely filled the thalamic parafascicular nucleus. Cells labeled from the medullary injections were seen ventrally to the fasciculus retroflexus in the subparafascicular nucleus. The two populations were mixed in a small area at the ventromedial border of the fasciculus retroflexus. No double labeled cells were observed. The present results indicate that caudal diencephalic cells which ascend to the striatum are different from those descending to the medulla oblongata and that they partially overlap.

Amygdala↗
PubMed1991

The efferent connections of the lateral septal nucleus in the guinea pig: projections to the diencephalon and brainstem.

The anterograde Phaseolus vulgaris-leucoagglutinin (PHA-L) tracing technique was used to determine the distribution of efferent fibers originating in the lateral septal nucleus of the guinea pig. For complementary detection of the chemical identity of the target neurons, double-labeling immunocytochemistry was performed with antibodies to PHA-L and to vasopressin, oxytocin, vasoactive intestinal polypeptide, serotonin or dopamine beta-hydroxylase, respectively. The hypothalamus received the majority of the PHA-L-stained septofugal fibers. Here, a specific topography was observed. (1) The medial and lateral preoptic area, (2) the anterior, lateral, dorsal, posterior hypothalamic and retrochiasmatic area, (3) the supraoptic, paraventricular, suprachiasmatic, dorsomedial, caudal ventromedial and arcuate nuclei, and (4) the tuberomammillary, medial and lateral supramammillary, dorsal and ventral premammillary nuclei always contained PHA-L-labeled fibers. The rostral portion of the ventromedial nucleus and the medial and lateral mammillary nucleus only occasionally showed weak terminal labeling. In other diencephalic areas, termination of PHA-L-labeled fibers was observed in the epithalamus and the nuclei of the midline region of the thalamus. In the mesencephalon, terminal varicosities occurred in the ventral tegmental area, interfascicular and interpeduncular nucleus, and periaqueductal gray. In addition, the dorsal and medial raphe nuclei of the metencephalon, together with the locus coeruleus and the dorsal tegmental nucleus, received lateral septal efferents.

Animals↗