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Circulation Research Jan 2009Tubular structures are a fundamental anatomical theme recurring in a wide range of animal species. In mammals, tubulogenesis underscores the development of several...
Tubular structures are a fundamental anatomical theme recurring in a wide range of animal species. In mammals, tubulogenesis underscores the development of several systems and organs, including the vascular system, the lungs, and the kidneys. All tubular systems are hierarchical, branching into segments of gradually diminishing diameter. There are only two cell types that form the lumen of tubular systems – either endothelial cells in the vascular system, or epithelial cells in all other organs. The most important feature in determining the morphology of the tubular systems is the frequency and geometry of branching. Hence, deciphering the molecular mechanisms underlying the sprouting of new branches from pre-existing ones is the key to understanding the formation of tubular systems. The morphological similarity between the various tubular systems is underscored by similarities between the signaling pathways which control their branching. A prominent feature common to these pathways is their duality – an agonist counterbalanced by an inhibitor. The formation of the tracheal system in is driven by fibroblast growth factor (FGF) and inhibited by Sprouty/Notch. In vertebrates, the analogous pathways are FGF and transforming growth factor β in epithelial tubular systems, or vascular endothelial growth factor and Notch in the vascular system.
Topics: Animals; Blood Vessels; Cell Movement; Cell Proliferation; Endothelial Cells; Mice; Morphogenesis; Neovascularization, Physiologic; Protein Isoforms; Proteoglycans; Rhombencephalon; Vascular Endothelial Growth Factor A
PubMed: 19179661
DOI: 10.1161/CIRCRESAHA.108.191494 -
The Journal of Comparative Neurology Sep 2003The development of neurons expressing gamma-aminobutyric acid (GABA) in the rhombencephalon and spinal cord of the sea lamprey (Petromyzon marinus) was studied for the... (Comparative Study)
Comparative Study
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.
Topics: Animals; Animals, Newborn; Body Patterning; Cell Count; Cell Size; Embryo, Nonmammalian; Embryonic and Fetal Development; Immunohistochemistry; Lampreys; Larva; Nerve Fibers; Neural Inhibition; Neurons; Proliferating Cell Nuclear Antigen; Rhombencephalon; Spinal Cord; Time Factors; gamma-Aminobutyric Acid
PubMed: 12866126
DOI: 10.1002/cne.10773 -
Science (New York, N.Y.) May 1999
Topics: Animals; Biological Evolution; Body Patterning; Cell Lineage; Jaw; Neural Crest; Rhombencephalon; Vertebrates
PubMed: 10383303
DOI: 10.1126/science.284.5418.1273c -
Child's Nervous System : ChNS :... Oct 2019Chiari malformations (CM) have been traditionally classified into four categories: I, II, III, and IV. In light of more recent understandings, variations of the CM have... (Review)
Review
PURPOSE
Chiari malformations (CM) have been traditionally classified into four categories: I, II, III, and IV. In light of more recent understandings, variations of the CM have required a modification of this classification.
METHODS
This article discusses the presentation, diagnostics, and treatment of the newer forms of hindbrain herniation associated with the CM type I.
RESULTS
The CM 1 is a spectrum that includes some patients who do not fall into the exact category of this entity.
CONCLUSIONS
While CM have been categorically recognized as discrete and individual conditions, newer classifications such as CM 0 and CM 1.5 exhibit some degree of continuity with CM 1; however, they require distinct and separate classification as symptoms and treatments can vary among these clinical subtypes.
Topics: Arnold-Chiari Malformation; Humans; Magnetic Resonance Imaging; Rhombencephalon; Syringomyelia
PubMed: 31049667
DOI: 10.1007/s00381-019-04172-6 -
Current Opinion in Genetics &... Dec 2012Retinoic acid (RA) regulates many cellular behaviors during embryonic development and adult homeostasis. Like other morphogens, RA forms gradients through the use of... (Review)
Review
Retinoic acid (RA) regulates many cellular behaviors during embryonic development and adult homeostasis. Like other morphogens, RA forms gradients through the use of localized sources and sinks, feedback, and interactions with other signals; this has been particularly well studied in the context of hindbrain segmentation in vertebrate embryos. Yet, as a small lipophilic molecule derived from a dietary source-vitamin A-RA differs markedly from better-studied polypeptide morphogens in its mechanisms of transport, signaling, and removal. Computational models suggest that the distinctive features of RA gradients make them particularly robust to large perturbations. Such features include combined positive and negative feedback effects via intracellular fatty acid binding proteins and RA-degrading enzymes. Here, we discuss how these features, together with feedback interactions among RA target genes, help enable RA to specify multiple, accurate pattern elements in the developing hindbrain, despite operating in an environment of high cellular and biochemical uncertainty and noise.
Topics: Animals; Cell Communication; Gene Expression Regulation, Developmental; Gene Regulatory Networks; Morphogenesis; Rhombencephalon; Signal Transduction; Tretinoin; Vertebrates
PubMed: 23266215
DOI: 10.1016/j.gde.2012.11.012 -
Wiley Interdisciplinary Reviews.... 2013The formation of a sharp interface of adjacent subdivisions is important for establishing the precision of tissue organization, and at specific borders it serves to... (Review)
Review
The formation of a sharp interface of adjacent subdivisions is important for establishing the precision of tissue organization, and at specific borders it serves to organize key signaling centers. We discuss studies of vertebrate hindbrain development that have given important insights into mechanisms that underlie the formation and maintenance of sharp borders. The hindbrain is subdivided into a series of segments with distinct anteroposterior identity that underlies the specification of distinct neuronal cell types. During early stages of segmentation, cell identity switching contributes to the refinement of borders and enables homogenous territories to be maintained despite intermingling of cells between segments. At later stages, there is a specific restriction to cell intermingling between segments that is mediated by Eph receptor and ephrin signaling. Eph-ephrin signaling can restrict cell intermingling and sharpen borders through multiple mechanisms, including the regulation of cell adhesion and contact inhibition of cell migration.
Topics: Animals; Cell Lineage; Ephrins; Humans; Morphogenesis; Neurogenesis; Receptors, Eph Family; Rhombencephalon; Signal Transduction
PubMed: 24014457
DOI: 10.1002/wdev.106 -
AJNR. American Journal of Neuroradiology Jan 2004We describe an infant in whom partial rhombencephalosynapsis was diagnosed by using MR imaging. The anterior vermis and nodulus were normally developed, but part of the...
We describe an infant in whom partial rhombencephalosynapsis was diagnosed by using MR imaging. The anterior vermis and nodulus were normally developed, but part of the posterior vermis was deficient. There was partial fusion of the hemispheres in the inferior part of the cerebellum. Partial rhombencephalosynapsis is described for the first time, and our findings support the recent embryologic observations.
Topics: Abnormalities, Multiple; Cerebellar Diseases; Cerebellum; Chromosome Pairing; Humans; Infant, Newborn; Magnetic Resonance Imaging; Male; Radiography; Rhombencephalon
PubMed: 14729524
DOI: No ID Found -
Journal of Neurology, Neurosurgery, and... Jun 2002
Topics: Adult; Arnold-Chiari Malformation; Cerebellum; Female; Headache; Humans; Hydrocephalus; Magnetic Resonance Imaging; Prognosis; Rhombencephalon
PubMed: 12122202
DOI: 10.1136/jnnp.72.suppl_2.ii38 -
Developmental Biology Dec 2017Neurons of the dorsal hindbrain and spinal cord are central in receiving, processing and relaying sensory perception and participate in the coordination of sensory-motor... (Review)
Review
Neurons of the dorsal hindbrain and spinal cord are central in receiving, processing and relaying sensory perception and participate in the coordination of sensory-motor output. Numerous cellular and molecular mechanisms that underlie neuronal development in both regions of the nervous system are shared. We discuss here the mechanisms that generate neuronal diversity in the dorsal spinal cord and hindbrain, and emphasize similarities in patterning and neuronal specification. Insight into the developmental mechanisms has provided tools that can help to assign functions to small subpopulations of neurons. Hence, novel information on how mechanosensory or pain sensation is encoded under normal and neuropathic conditions has already emerged. Such studies show that the complex neuronal circuits that control perception of somatosensory and viscerosensory stimuli are becoming amenable to investigations.
Topics: Animals; Body Patterning; Nerve Net; Neural Tube; Neurogenesis; Rhombencephalon; Spinal Cord
PubMed: 27742210
DOI: 10.1016/j.ydbio.2016.10.008 -
Physiology & Behavior Sep 2019Glucose is the required metabolic substrate for the brain. Yet the brain stores very little glucose. Therefore, the brain continuously monitors glucose availability to... (Review)
Review
Glucose is the required metabolic substrate for the brain. Yet the brain stores very little glucose. Therefore, the brain continuously monitors glucose availability to detect hypoglycemia and to mobilize system-wide responses to protect and restore euglycemia. Catecholamine (CA) neurons in the hindbrain are critical elements of the brain's glucoregulatory mechanisms. They project widely throughout the brain and spinal cord, innervating sites controlling behavioral, endocrine and visceral responses. Hence, CA neurons are capable of triggering a rapid, coordinated and multifaceted response to glucose challenge. This article reviews experimental data that has begun to elucidate the importance of CA neurons for glucoregulation, the functions of specific CA subpopulations in the ventrolateral medulla, and the extended circuitry through which they engage other levels of the nervous system to accomplish their essential glucoregulatory task. Hopefully, this review also suggests the vast amount of work yet to be done in this area and the justification for engaging in that effort.
Topics: Animals; Glucose; Medulla Oblongata; Neurons; Rhombencephalon
PubMed: 31173784
DOI: 10.1016/j.physbeh.2019.112568