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At least 19 recordsLinked to original sources

PubMed1988

Tyrosine hydroxylase and serotonin containing cells in embryonic rat rhombencephalon: a whole-mount immunocytochemical study.

Rhombencephala from rat embryos were processed as whole-mounts for immunocytochemical detection of monoaminergic cell populations, using antibodies to tyrosine hydroxylase (TH) and serotonin (5-HT). Specific advantages of the whole-mount technique over the classical serial-section method were that even isolated immunoreactive (IR) cells could be detected easily, and three-dimensional relationships could be ascertained without the need for serial reconstruction. Embryos between embryonic days (E) 12 and 16 (the day following nocturnal mating being considered as E1) were used in this study. Both TH and 5-HT immunoreactivities were already detectable at E12, even in the smallest embryos (crown-rump length: 6 mm), but there was a striking difference in the number and regional distribution of these two types of IR cells. TH was expressed in several cell groups located in the rostral rhombencephalon (the presumed anlage of the A4-7 complex) as well as in the caudal rhombencephalon (the presumed anlagen of groups A1-2 and C1-3), whereas 5-HT was expressed in very few cells located near the rostral border of the rhombencephalon (presumed anlage of the B4-9 complex). Although the three-dimensional distribution of the TH-IR cell groups underwent some modifications during the period studied, its general pattern remained relatively stable after E12. This contrasted with the sequential appearance of the 5-HT-IR cell groups and their spatial transformations during this period. Using the rhombencephalic isthmus as a landmark, we found that conspicuous 5-HT-IR fibre bundles penetrated into the mesencephalon from E13 onwards, but that the 5-HT IR cell bodies were exclusively located caudal to the borderline between the mesencephalon and the rhombencephalon (the rhombencephalic isthmus). We therefore suggest the term "rostral rhombencephalic raphe nuclei" for the rostral 5-HT cell groups instead of "mesencephalic raphe nuclei," which is a misnomer. Close spatial association between TH and 5-HT-IR elements was observed mainly in the caudal rhombencephalon, where 5-HT-IR fibres coursed through an area containing numerous TH-IR cell bodies (the presumed anlagen of groups A1-2 and C1-3).

Animals↗

PubMed2003

Ontogeny of gamma-aminobutyric acid-immunoreactive neurons in the rhombencephalon and spinal cord of the sea lamprey.

The development of neurons expressing gamma-aminobutyric acid (GABA) in the rhombencephalon and spinal cord of the sea lamprey (Petromyzon marinus) was studied for the first time with an anti-GABA antibody. The earliest GABA-immunoreactive (GABAir) neurons appear in late embryos in the basal plate of the isthmus, caudal rhombencephalon, and rostral spinal cord. In prolarvae, the GABAir neurons of the rhombencephalon appear to be distributed in spatially restricted cellular domains that, at the end of the prolarval period, form four longitudinal GABAir bands (alar dorsal, alar ventral, dorsal basal, and ventral basal). In the spinal cord, we observed only three GABAir longitudinal bands (dorsal, intermediate, and ventral). The larval pattern of GABAir neuronal populations was established by the 30-mm stage, and the same populations were observed in premetamorphic and adult lampreys. The ontogeny of GABAergic populations in the lamprey rhombencephalon and spinal cord is, in general, similar to that previously described in mouse and Xenopus.

Animals↗

PubMed2004

Immunohistochemical distribution of neuropeptide Y in the mesencephalon and rhombencephalon of carp, Cyprinus carpio L. (Cyprinidae: Teleostei).

The localization of neuropeptide Y (NPY)-immunoreactive elements was investigated in the mesencephalon and rhombencephalon of carp, Cyprinus carpio, by using antisera raised against porcine NPY and the immunoperoxidase technique. Concurrently, to identify the distribution of NPY-immunoreactivity, we developed an atlas of the studied areas based on Nissl-stained sections. The NPY-immunoreactive (NPY-ir) elements were located in many zones of the mesencephalon and rhombencephalon. In the mesencephalon, positive fibers were the most abundant elements while neurons were scarce. The rhombencephalon rostral part was characterized by a low to moderate fiber density, distributed in the ventro-medial and ventro-lateral region. Differently the caudal part of the rhombencephalon exhibited several NPY-ir elements. In particular, a high density of immunoreactivity was located in the gustatory area at the level of the nucleus (n.) originis nervi glossopharyngei, in the n. nervi vagi, and in the vagal lobe. The latter can be considered a valid neuroanatomical model for the study of gustatory signal processing in vertebrates. Our results regarding the primary gustatory centers give neuroanatomical support to the view that NPY may act as a neurotransmitter and/or a neuromodulator in a wide neural network for feeding behavior control.

Animals↗

PubMed1987

Development of the precerebellar nuclei in the rat: I. The precerebellar neuroepithelium of the rhombencephalon.

Short-survival thymidine radiograms from rat embryos aged 13-19 days were analyzed to delineate the precerebellar neuroepithelium of the rhombencephalon. The original definition of the term "rhombencephalon" was modified to refer only to the unique dorsal portion (surface plate) of the medulla and pons where the neural groove fails to fuse and, instead, the medullary velum covers the rhomboid lumen of the fourth ventricle. Initially, the neuroepithelial tissue of the rhombencephalon consists of a pair of rostral and caudal bridgeheads: the former the primary neuroepithelium of the cerebellum and the latter the primary neuroepithelium of the octavo-precerebellar system. The spatial relationship between the cerebellar and precerebellar neuroepithelia soon changes as a result of ongoing morphogenetic events, such that the cerebellar primordium assumes a dorsal position and the precerebellar primordium a ventral position, and the distance between the two decreases. Concurrently the tela choroidea invaginates into the fourth ventricle and a secondary precerebellar neuroepithelium develops. The rostral portion of the secondary precerebellar neuroepithelium grows forward along the choroid plexus and forms the medial recess of the anterior fourth ventricle, while its caudal portion grows in the opposite direction beneath the medullary velum and forms the rostral wall of the posterior fourth ventricle. Evidence will be presented in the succeeding papers that the primary precerebellar neuroepithelium first generates the neurons of the inferior olive that migrate by a circumferential intramural (parenchymal) route to their destination. Next, the neurons of the lateral reticular and external cuneate nuclei are generated. These migrate by a posterior extramural (superficial) route and settle contralaterally. Subsequently, the primary precerebellar neuroepithelium produces the neurons of the nucleus reticularis tegmenti pontis and these form the anterior extramural migratory stream and settle ipsilaterally. Finally, the secondary precerebellar neuroepithelium produces the latest generated neurons of the basal pontine gray that follow the anterior extramural stream and settle ipsilaterally.

Animals↗

PubMed1995

[Comparative studies of rhombencephalon vascularization in rabbit and man in light of anatomic and microangiographic studies].

A comparative study of a microvascularization of the rhombencephalon, especially pre- and capillary system, in rabbits and in humans was performed. It was intended to find out whether there were any similarities and differences in rhombencephalon microvascularization of a rabbit and man. The study was carried out on 75 (50--female, 25--male) mixed-race rabbits aged 4 months, as well as on 30 (15--females, 10--males) human brains that had been dissected free from cadavers, aged from 20 up to 70 years. Angiography of sections of the rhombencephalon in rabbits and cadavers was performed. The vessels were investigated after the introduction of Micropaque contrast medium, under controlled pressure, into an investigated vessel. Intravital injection of the contrast into rabbit's vessel was beneficial for the experiment. Radiography of intact brains as well as sections of the frontal plane was accomplished. Large arterial vessels were measured, with the results being subjected to statistical analysis (Table 1-2, Fig. 1-7). Microvascularization of the medulla oblongata and of the pons in rabbits were similar to those in its human counterparts, whereas the vascular system of the cerebellum was different. The results of micrographic studies were not always the same as described by Bochenek et al. The anatomical forms that had not been previously described were noted: para--medial arteries to the medulla oblongata and the pons; lateral arteries to the medulla oblongata and the pons; posterior arteries to the medulla oblongata; branches of the upper artery of the cerebellum branching and the simple ones with few lateral branches. The central or medial artery that follows the central sulcus was separate.

Adult↗

PubMed1990

The human rhombencephalon at the end of the embryonic period proper.

The human rhombencephalon at 8 postovulatory weeks (stage 23) is described and illustrated for the first time with the aid of silver-impregnated sections and graphic reconstructions. The motor and sensory trigeminal nuclei were among those studied, and the latter was found to be almost contiguous to the dentate nucleus. Fibers to the principal sensory nucleus join the mesencephalic trigeminal tract, which also seems to be connected with the motor fibers. Fine fibers from the sensory root join the tractus solitarius, which appears to receive connections from the facial, glossopharyngeal, and vagal nerves. Main and accessory abducent nuclei are evident. A part (the Kappenkern des Facialisknies) of the nucleus funiculi teretis is particularly prominent. The presence of the pyramidal decussation during the embryonic period is noted for the first time. The arrangement of nuclei and tracts at 8 weeks is shown to be closely similar to that present in the newborn, and it is likely that the rapid growth of the rhombencephalon during the embryonic period proper is associated with correspondingly early functional activity.

Cell Movement↗

PubMed2002

Distribution of GFAP immunoreactive structures in the rhombencephalon of the sterlet (Acipenser ruthenus) and its evolutionary implication.

Previous studies have revealed that although the brains of cypriniform teleosts (iberian barb, Barbus comiza; carp, Cyprinus carpio; goldfish, Carassius auratus) are rich in glial fibrillary acidic protein (GFAP), they have, however, areas devoid of GFAP immunoreactivity. The largest ones of these are in the rhombencephalon, e.g., the zones of the sensory and motor neurons in the vagal lobe. Our studies in amniotes suggested that the GFAP immunonegative areas could be characteristic of the more advanced brains (avian and mammalian), whereas no similar areas were found in reptiles. A similar tendency was found in the Chondrichthyes, i.e., GFAP immunonegative areas appeared as brain complexity progressed. The question arose whether the GFAP immunonegative brain areas in the Teleostei were also the result of such a tendency. Within the radiation of ray-finned fishes (Actinopterygii), Chondrostei represent a less advanced level as compared to the Teleostei. Therefore, the distribution of GFAP immunoreactivity was investigated in the rhombencephalon of the sterlet (Acipenser ruthenus) as a representative of Chondrostei, and in the carp. Serial vibratome sections were processed according to the avidin-biotinylated horseradish peroxidase method.Several comparable GFAP immunoreactive structures were found in the two species: the dense periventricular ependymoglial plexus, the midsagittal glial septum, the small glial septa separating the nerve fiber bundles, and the wide glial endfeet lining the meningeal surface. In the vagal lobe in the zones adjacent to the meningeal and ventricular surfaces, the glial structures also proved to be similar. In contrast to the carp, however, no areas were found devoid of GFAP immunoreactivity in the sterlet.The results suggest that this trend of glial evolution, i.e., GFAP immunonegative areas appearing as brain complexity progressed, is a common feature shared by Actinopterygii, Amniota, and Chondrichthyes, despite their separate evolutionary histories. J. Exp. Zool. 293:395-406, 2002.

Animals↗

PubMed1992

Glial fibrillary acidic protein and vimentin immunohistochemistry in the posterior rhombencephalon of the Iberian barb (Barbus comiza).

The gustatory centers (vagal lobes and facial lobe) and the tegment of the posterior rhombencephalon of the Iberian barb (Barbus comiza) have been studied using anti-glial fibrillary acidic protein (anti-GFAP) and anti-vimentin immunohistochemical techniques. GFAP immunoreactivity was found in the tegment and in a part of the vagal lobes while vimentin immunoreactivity was located in the tegment. Two immunopositive cell types were found: ependymocytes and radial astrocytes. Since the distribution of GFAP in the barb rhombencephalon corresponds with zones previously described as cholinergic, the GFAP-immunopositive radial astrocytes might be involved in acetylcholine metabolism.

Animals↗

PubMed1995

A concept of the development of the mammalian rhombencephalon based on physical rotational forces.

The premammalian forms do not show the metencephalic and myelencephalic divisions of the rhombencephalon. The seven longitudinal grey columns, in relation to the seven nerve components are direct cranial uninterrupted continuations from the spinal cord. The isthmus rhombencephali is a tubular structure. The phylogenetically ancient ependyma rich in tanycytes lines the fourth ventricle. The neural canal does not open into the subarachnoid space and the ependyma never becomes directly continuous with the pia mater. On the other hand, in mammals, the rhombencephalon is divided into the metencephalon and myelencephalon. The seven longitudinal grey columns get fragmented and their cell masses undergo migrations. The isthmus loses its tubular nature and undergoes modifications. The fourth ventricle opens into the subarachnoid space through three openings. The phylogenetically ancient ependyma is retained as a continuous structure only along the inferolateral angle of the fourth ventricle. At the openings of the lateral recesses, the ependyma becomes directly continuous with the pia, a neural crest derivative. The oval bundle, the corpus trapezoideum and the myelencephalic component of the nuclei pontis show extensive migrations. The above phenomena can be explained by physical rotation forces and not merely by migrations.

Animals↗

PubMed1976

Comparative anatomy of the locus coeruleus. II. Organization and projection of the catecholamine containing neurons in the upper rhombencephalon of the frog, Rana catesbiana.

The organization and projection of the catecholamine (CA) containing neurons in the upper rhombencephalon were experimentally investigated with histofluorescence method in the brain of the bullfrog, Rana catesbiana. A small number of catecholamine containing neurons are located in the upper rhombencephalon. These neurons do not send ascending fibers to contribute CA projection to the forebrain, but give rise to relatively short axons to innervate the cerebellum and neighbouring reticular formation. Judging from their anatomical aspects, it seems that the structure homologous to the mammalian locus coeruleus is not present in the amphibian brain.

Animals↗

PubMed1986

Volumetric development of the fetal telencephalon, cerebral cortex, diencephalon, and rhombencephalon including the cerebellum in man.

Fresh volumes of the human telencephalon, cerebral cortex, diencephalon, and of the rhombencephalon including cerebellum were determined in a series of 10 normal specimens ranging in age from 63 to 176 days after conception. The volumetric growth of these parts shows a nonlinear dependence on age with a smaller increase during the 3d ontogenetic month and a stronger increase from the 4th month on. These data were analyzed together with previous measurements of 28 brains taken from the Yakovlev Collection in Washington, D.C., and the Vogt Collection in Düsseldorf. These brains range in age from 137 to 22,900 days after conception. These samples were reproduced in a model using sigmoid logistic functions. The entire brain and all analyzed parts show a monotonous growth. The individual regions develop heterochronously. The diencephalon is the first part to reach its ideal volume, with a main growth spurt between 100 and 420 days after conception. The rhombencephalon including the cerebellum is the last, with its main growth spurt between 240 and 650 days after conception. The growth of the entire brain is determined to a great extent by that of the telencephalon, having a main growth spurt between 175 and 580 days after conception. The prenatal growth is described separately with the asymmetric sigmoid function according to Gompertz. This yields a better approximation of the data collected from the early prenatal period.

Cerebellum↗

PubMed1991

Population-specific modulation of 5-HT expression in cultures of embryonic rat rhombencephalon.

This study aimed at analyzing the regulation of in vitro serotonin expression by neurons taken from different regions of the embryonic rat rhombencephalon. We studied the influence of co-culture with alarplate tissue using immunocytochemical and biochemical methods. Computer-assisted densitometry was used to estimate the co-culture effects on the serotonin content of the cell bodies. The more dynamic aspects of serotonin expression, such as synthesis and release, were studied by measuring (3H)serotonin newly synthesized from (3H)tryptophan. The density of the immunostaining was significantly decreased in B1,B2 cells by co-culture with both caudal and rostral alar-plate tissue. For B4-B9 cells, only co-culture with rostral alar-plate tissue produced a significant decrease. The de novo synthesis of serotonin was significantly decreased in B1,B2 neurons co-cultured with caudal alar-plate tissue only. Once again, the B4-B9 cells proved to be less influenced by the experimental conditions, as co-culture with both types of alar-plate tissue produced no significant effect. We concluded that the in vitro expression of serotonin can be modulated by environmental factors, but the relative influence of these factors is very different in rostral versus caudal serotonin expressing cell populations.

Animals↗

PubMed1989

Distribution of glial fibrillary acidic protein (GFAP)-immunoreactive astrocytes in the rat brain. II. Mesencephalon, rhombencephalon and spinal cord.

The topographical mapping of glial fibrillary acidic protein (GFAP)-immunoreactivity was performed in coronal serial sections of the rat mesencephalon, rhombencephalon and spinal cord. Relative to a background of poor or moderate overall staining of the mesencephalon, the interpeduncular nucleus, substantia nigra and the periaqueductal grey matter were prominent by their intense GFAP-immunoreactivity. The pons and particularly the medulla contained more GFAP-labelled elements compared with the mesencephalon. The spinal trigeminal nucleus and Rolando substance were distinguished by their intense staining. Large fibre tracts were usually poor in immunoreactive GFAP. In a concluding discussion, findings relevant to the GFAP-mapping of the whole rat CNS are evaluated with regard to possible reasons underlying the observed differential distribution of GFAP-immunoreactivity.

Animals↗

PubMed1993

Effects of experimentally induced hyperammonemia on glial fibrillary acidic protein (GFAP) in the rhombencephalon of goldfish (Carassius auratus L.).

This experimental study was made to know the effect of hyperammonemia on glial fibrillary acidic protein (GFAP) in the glial cells of posterior rhombencephalon in the goldfish (Carassius auratus L.). Hyperammonemia was induced by elevating the ammonia concentration in the tank water to 0.88 mM with ammonium chloride; the ammonia level in the control tank water was < 0.1 mM. The GFAP levels were measured at 8, 16, 30, 60, 90 and 120 days. GFAP was quantified with a digital analysis system and a transient heterogeneous decrease of GFAP was observed. Hyperammonemia mostly affected GFAP in the astrocyte processes associated with cholinergic pathways. An explanation for the adaptive response to hyperammonemia by fish astrocytes is suggested.

Ammonia↗

PubMed1997

Morphological and morphometric analysis of serotonin-containing neurons in primary dissociated cultures of human rhombencephalon: a study of development.

Primary dissociated cultures of rhombencephalon were prepared from 5-9-week-old human fetuses. Half of some cultures were treated by two non-competitive N-methyl-D-aspartate antagonists, namely 1-(2-thienyl)cyclohexylpiperidine (TCP) and cis-Pip/Mel-[1-(2-thienyl)-2-methyl-cyclohexyl]piperidine (GK11) in negative enantiomeric form, which enhance the survival of human fetal central nervous system cells in culture. At different days in vitro, the treated and the control cultures were processed for immunocytochemical detection of serotonin-containing neurons which were studied by morphological and morphometric analysis. Statistical analysis showed that the surface of the stained neurons increased as a function of two parameters of time, the gestational age of the cells and the duration of the cultures. The complexity of the shape of the serotonin neurons characterized by the shape factor, the number of bifurcations and the morphological feature (bipolar or multipolar) was found to increase with the gestational age. It appears that the in vitro development of the embryonic cells which represents stages of maturation and differentiation can be specifically evaluated. Such an analysis of fetal central nervous system cells improves the knowledge of factors important in grafting experiments. We verified that the two drugs do not appreciably alter the in vitro development of the treated cells; thus they may be considered as promising drugs for human neuroprotection.

Cell Differentiation↗

PubMed1988

Fetal rhombencephalon: normal US findings.

Using ultrasound (US), the authors examined 25 embryos that were 8-10 menstrual weeks old for gestational age and the presence of a small cystic structure (3-4 mm) in the posterior aspect of the cranium. This structure was seen in all embryos. The US images of an in vitro embryo at 8 weeks menstrual age were also evaluated for anatomic correlation. Analysis of these US images determined that the cystic structure was the open rhombencephalon or hindbrain. Follow-up US studies or postpartum clinical examinations of the 25 in utero embryos demonstrated no abnormal posterior cranial cystic structures or neurologic deficits. This first-trimester structure should be considered a normal finding, since it develops into the normally proportioned fourth ventricle after the 11th menstrual week.

Female↗

PubMed2007

The cisterna magna septa: vestigial remnants of Blake's pouch and a potential new marker for normal development of the rhombencephalon.

OBJECTIVE: The purpose of this study was to show the normal sonographic embryologic anatomy of the cisterna magna septa, fourth ventricle, and cerebellar vallecula at various stages of development and our experience with their variable appearance in multiple planes and to discuss the probable relationship between the cisterna magna septa, Dandy-Walker continuum, mega cisterna magna, and persistent Blake's pouch. METHODS: Retrospective and prospective selection of examples of cisterna magna septa was performed over approximately a 12-month period. Standard and nonstandard imaging planes were adopted as necessary. RESULTS: The septa are typically seen inferoposterior to the cerebellar vermis, usually straight and parallel, arising at the cerebellovermian angle and coursing posteriorly to the occipital bone. The cisterna magna septa become contiguous with the roof of the fourth ventricle inferior to the cerebellar vermis. The cerebrospinal fluid space enclosed between the cisterna magna septa is in direct contiguity with the fourth ventricle via the vallecula and is always completely anechoic because it develops intra- and not extra-axially. CONCLUSIONS: We propose that the cisterna magna septa represent the walls of Blake's pouch, a phylogenetic vestigial structure observed during ontogeny. Additionally, our observations support current opinion that a persistent Blake's pouch and mega cisterna magna represent (less severe) abnormalities within the Dandy-Walker continuum. The cisterna magna septa therefore are a marker of normal development of the roof of the rhombencephalon. Deviation from their normal appearances should prompt a closer assessment for associated abnormalities of the cerebellum, vermis, and brain stem by additional imaging in orthogonal planes with either sonography or magnetic resonance imaging.

Cisterna Magna↗

PubMed2002

Immunohistochemical localization of nerve growth factor, glial fibrillary acidic protein and ciliary neurotrophic factor in mesencephalon, rhombencephalon, and spinal cord of developing mongolian gerbil.

The distribution of the nerve growth factor (NGF), the glial fibrillary acidic protein (GFAP) and the ciliary neurotrohic factor (CNTF) was performed in coronal sections of the mesencephalon, rhombencephalon and spinal cord in the developing Mongolian gerbils. Generally, NGF specifically recognizes neurons with the NGF receptor, whereas GFAP does the glia, and CNTF does the motor neurons. The receptor expression was examined separately in gerbils between embryonic days 15 (E15) and postnatal weeks 3 (PNW 3). The NGF-IR was first observed in the spinal cord at E21, which might be related to the maturation. The GFAP reactivity was peaked at the postnatal days 2 (PND2), while the highest CNTF-reaction was expressed at PNW 2. The GFAP stains were observed in the aqueduct and the spinal cord, which appeared to project laterally at E19. The CNTF was observed only after the birth and found in both the neurons and neuroglia of the substantia nigra, mesencephalon, cerebellum and the spinal cord from PND1 to PNW3. These results suggest that NGF, GFAP and CNTF are important for the development of the neurons and the neuroglia in the central nervous system at the late prenatal and postnatal stages.

Animals↗