Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Rhombencephalon”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 37 records · Page 2Linked to original sources
PubMed1997

[Genetic control of rhombencephalon development by Hox genes studied in bird embryo by the quail-chick chimera method].

The rhombencephalic neural tube is transiently segmented along the anteroposterior axis into 8 rhombomeres. Each rhombomere, as well as its derived neural crest cells, is characterized by the expression of a specific set of Hox genes which constitute its Hox code. This code is supposed to define the morphogenetic program of these cells according to their position. We took advantage of the quail/chick chimera system to study the regulation of Hox gene expression in neural tube and neural crest cells. We have therefore ectopically transplanted the presumptive territories of the future rhombomeres and studied the evolution of their Hox code. We evidence in the posterior rhombencephalon and the spinal cord a posteriorising signal able to induce Hox gene expression, to repress anterior molecular markers and to control the subsequent development of the neural tube. This signal is conveyed horizontally in the plane of the neuroepithelium and vertically from the mesoderm to the ectoderm. The anteroposterior identity of the neural crest cells seem independent from this inducer after formation of the neural fold.

Animals↗
PubMed1983

Retrograde HRP identification of neurons in the rhombencephalon and spinal cord of the rat that project to the dorsal mesencephalon.

Neurons in the rhombencephalon and spinal cord of the rat that project to the dorsal midbrain were identified using the HRP retrograde neuroanatomical tracing method. Retrogradely labeled neurons were most numerous in the reticular formation, specifically in nucleus pontis oralis, caudalis, and gigantocellularis and in the sensory trigeminal complex. Neurons that project were also found in certain raphe nuclei, the parabrachial nuclei, the deep cerebellar nuclei, the vestibular cochlear complex, and the spinal cord. The diverse distribution of neurons that project to the midbrain is understandable in the context of the known diverse functions of the region, which include a role in sexual and other behaviors, nociception, and various autonomic functions.

Animals↗
PubMed1981

Topographic atlas of somatostatin-containing neuron system in the avian brain in relation to catecholamine-containing neuron system. II. Mesencephalon, rhombencephalon, and spinal cord.

With the indirect immunofluorescence technique of Coon's and collaborators, overall distribution of the somatostatin (SRIF)-positive neurons system in the avian lower brain stem was explored. Numerous cell somata containing SRIF were identified in the interpeduncular nucleus and substantia grisea centralis (GCT) at the level of the nucleus nervi trochlearis. Furthermore, a moderate number of SRIF-positive neurons were seen in the tectum opticum, nucleus tractus solitarii, and spinal cord. Scattered labeled cells were noticed in the rhombencephalon. A dense network of SRIF-positive fibers was distributed widely in the lower brain stem of birds. Their locations corresponded in many cases to the areas where SRIF-positive neurons were found. The present study also presents the distribution of the catecholamine (CA) neuron system in the avian lower brain stem. Possible interactions between SRIF and CA neurons systems are briefly discussed.

Animals↗
PubMed1981

Transitory subependymal cysts in the developing rat rhombencephalon.

A bilaterally symmetrical cystic cavity is situated in the subependymal neuropil of the rostral rhombencephalon of the rat during the perinatal period of ontogeny. These cysts are formed by the confluence of enlarged extracellular spaces in this region between E18 and E20. The cysts are present for about 2 weeks but disappear on about P15 without trace. They have a maximal volume of about 0.004 to 0.006 mm3 on P2, with a rostrocaudal extension of about 200 microm. Their shape is characterized by a medial convexity and a lateral concavity, and they have their maximal circumference at about the middle of the rostrocaudal axis. The caudal portion is juxtaposed to the subependyma, while the rostral part lies in the neuropil of the presumptive griseum centrale pontis. In the lumen and the wall of the cysts are found numerous macrophages, glioblasts and some degenerating axons and dendrites. The significance of these cysts in the context of morphogenesis and the origin of the numerous macrophages within them are both unresolved.

Animals↗
PubMed1980

Familial brain tumors: rhombencephalon-astrocytoma grade I in father and son.

This report presents a clinico-pathologic study of low-grade astrocytoma in father and son whose relatives had multiple sclerosis and Cockayne syndrome. The corresponding location within the rhombencephalon and the coincidence of tumor type probably imply that an endogenous genetic factor has influenced the astrocyte cell line.

Adolescent↗
PubMed1983

Intraganglionic distribution of the primary afferent neurons in the frog glossopharyngeal nerve and its transganglionic projection to the rhombencephalon studied by HPR method.

Anterograde transport of horseradish peroxidase (HRP) along the bullfrog IXth nerve was studied 6-16 days after application of HRP to the cut end of either the IXth nerve trunk or its distal 2 branches. The jugular and IXth nerve ganglia attached to the rhombencephalon were removed after fixation and serial sections of 50 microns in thickness were stained by the Graham and Karnovsky method. Of all the primary afferent neurons in the IXth nerve, 62% of the cell bodies were distributed within the IXth nerve ganglion, the remaining 38%, within the jugular ganglion. Similar distribution was found with the cells belonging to each of the IXth nerve branches. A part of the transganglionic IXth nerve fibers entering the medulla oblongata ascended to the cerebellar peduncle while the majority descended along the fasciculus solitarius. Some of the descending fibers in the fasciculus extended to the dorsal field of the spinal cord at the third spinal nerve, while some others run to join the descending tract of trigeminal nerve.

Afferent Pathways↗
PubMed1984

Visual, cortical somatosensory and brainstem auditory evoked potentials following incidental irradiation of the rhombencephalon.

Visual, cortical somatosensory and brainstem auditory evoked potentials were recorded before incidental irradiation of the rhombencephalon and at 11 weeks and eight months after completion of treatment. No patient experienced neurological symptoms during this period. No consistent changes in evoked potentials were found. The failure to demonstrate subclinical radiation-induced demyelination suggests either that the syndrome of early-delayed radiation rhombencephalopathy occurs in an idiosyncratic manner, or that any subclinical lesions are not detectable by serial evoked potential recordings.

Adenocarcinoma↗
PubMed1979

[Cultivation of whole brain slices: a description of the method and the results of its use for culturing the rhombencephalon and midbrain of chick embryos].

A method and device for obtaining embryo brain slices are described. Results of cultivation of slices of rhombencephalon and mesencephalon are presented obtained in accord with a proposed technique of the "swimming float" (Olenev, 1979). With this cultivation, original topographical relations between brain nuclei and fibrillar tracts remain unchanged that enables us to compare these cultures with histological sections of brain to identify strictly the structures being cultivated. Cultured neurons of nuclei of XII and VIII pairs of cranial nerves have been first described in addition to various divisions of the reticular formation commissura cochlearis dorsalis. Compared to cells examined in the in vivo conditions, neurons of the nucleus cochlearis laminaris, grown in tissue culture conditions, do not make plate-forming structures; dendrites of the neurons of III layer of tectum opticum do not develop. This may be explained by the absence in vitro of any stimulating influence from the acustic ganglion fibres and ganglion cells of the retina on these morphogenetic processes.

Animals↗
PubMed1984

Topographical differences of carboxylic esterases in the rhombencephalon and mesencephalon of the turtle (Lissemys punctata granosa).

The present contribution deals with histochemical mapping of acetylcholinesterase, butyrylcholinesterase and non-specific esterase in the rhombencephalon and mesencephalon of the turtle (L. punctata). The study reveals that all the neurons of this species are strongly positive for AChE, irrespective of their sensory or motor nature. The enzyme is localized in cell bodies and dendritic processes, while the axons are completely negative. Thus its presence in the fibrous components is not seen except in the superficial layers of optic tectum. Non-specific esterase activity is quite prominent in all the neurons, while the neuropil is weakly positive in most of the nuclei with a few exceptions. The blood vessels are strongly positive throughout the area. In sharp contrast to these enzymes. BChE is completely missing in all the constituents.

Acetylcholinesterase↗
PubMed1983

[A new concept of Pierre Robin syndrome and disease: dysneurulation of the rhombencephalon].

Pierre Robin's syndrome, a disorder apparently constituted by peripheral signs, is in fact the result of early major disturbances of ontogenesis of motor and regulatory organization of the fetal rhombencephalon. This is confirmed by the presenting signs in neonates with Pierre Robin's syndrome: --electrophysiological deglutition and sucking disorders as demonstrated on electromyography; --disorders in tone of tongue, pharyngeal and laryngeal muscles; --cardiac and respiratory regulatory disorders as shown by central and obstructive apneas with diminished oxygen pressure and bradycardia of central origin during sleep; and gastro-esophageal reflux. Associated signs indicating that Pierre Robin's syndrome is a separate disease entity are: --evidence of a rhomboencephalic neurocristopathy (malformation of 3rd and 4th aortic arch arteries, thymic and parathyroid hypoplasia) associated with a central rhomboencephalic lesion and resulting in dysneurulation; --mesencephalic lesion as seen in Stickler's syndrome and prosencephalic lesion as in Binder's syndrome, indicating more diffuse cephalic dysneurulation. The common origin of Di George's and Pierre Robin's syndromes is emphasized, the neonatal microretrognathism of the latter syndrome being a bulbar sign. Pierre Robin's syndrome has a poor prognosis, as there is a fatal outcome in one out of four neonates affected, and it appears to be an affection that is the clinical expression of an early major anomaly of cephalic neurulation.

DiGeorge Syndrome↗
PubMed1981

Spinal projections from the rhombencephalon in the toad.

Rhombencephalic cell groups projecting to the spinal cord are demonstrated following single pressure injections and/or iontophoretic ejections of HRP solution in either cervical or lumbar enlargements of the toad spinal cord. A group uptake and transport of HRP were obtained with both application techniques, when sufficiently long survival times (8-11 days) were used. Following injections in the cervical cord labeled cells are located mostly in the ventral nucleus of the VIIIth nerve and in the medial zone of the rhombencephalic reticular formation, i.e. the nucleus reticularis inferior, medius and superior. Following injections in the lumbar enlargement the majority of labeled cells are situated in the caudalmost portion of the ventral nucleus of the VIIIth nerve and in the nucleus reticularis inferior. These observations indicate that in the toad the main supraspinal descending pathways from the rhombencephalon originate in the ventral nucleus of the VIIIth nerve and the medial zone of the reticular formation, and that both these pathways are somatotopically organized.

Animals↗
PubMed1999

Shaw-like potassium currents in the auditory rhombencephalon throughout embryogenesis.

The Shaw subfamily of potassium channel genes, including Kv3.1, are highly expressed within the auditory nuclei of the brainstem, where they have been implicated in the characteristic response properties of particular types of neurons. Potassium currents carried by Kv3.1 are voltage-dependent, have a high activation threshold, are slow to inactivate, and are very sensitive to 4-aminopyridine (4-AP) and tetraethylammonium (TEA). We have investigated the developmental appearance of potassium currents in cell cultures from nucleus magnocellularis and its precursor neuroblasts from the acoustico-vestibular anlage of the chicken. Whole-cell patch recordings revealed that high-threshold, sustained, outward currents were present in 91% of neuroblasts. These currents displayed high sensitivities to TEA and 4-AP. The remaining 9% of neuroblasts exhibited only transient outward currents. Most cells (74%) had both a sustained and an initial transient component of outward current. These current types were observed throughout embryogenesis, beginning with the earliest ages (embryonic day [E]2). During proliferation and migration, and early neuronal differentiation, current levels were low; they incremented gradually during the time when the first synapses occur on dendrites and increased 2- to 3-fold just before hatching, when axosomatic synapses form. These findings suggest that the Shaw subfamily of channels in nucleus magnocellularis may be involved in early neuronal development, as well as in synaptic function later on.

4-Aminopyridine↗
PubMed2002

Perturbation of extracellular matrix prevents association of the otic primordium with the posterior rhombencephalon and inhibits subsequent invagination.

In the avian embryo, the otic primordia become visible by Hamburger and Hamilton stage 10 as a pair of thickened regions of head ectoderm. In contrast to other epithelial primordia, invagination occurs by means of formation of a series of folds in distinct areas of the primordium, giving the otic vesicle a box-like appearance. Because previous work has shown that otic invagination is ATP and calcium independent, it is unlikely that cytoskeletal changes are the primary mechanism responsible for invagination as in other epithelial primordia. Interaction of the primordium with surrounding tissues may provide the force for otic invagination. These extracellular forces may be transduced through extracellular matrix macromolecules and their cell surface receptors. This investigation tests the hypothesis that fusion of the otic and hindbrain basal laminae between stages 11 and 13 is necessary for normal invagination. Perturbation of binding of the otic primordium to the neural tube was accomplished by means of microinjection of antibodies to various extracellular matrix components and integrin subunits into the head mesenchyme in the otic region at stage 10. Only antibodies to laminin and integrins caused detachment of the otic primordium from the hindbrain. These experiments suggest that fusion of the otic and hindbrain basal laminae is required for subsequent invagination and, furthermore, that this event is mediated by components of the extracellular matrix.

Animals↗