ISSN:0022-3034    

DOI:10.1002/neu.480240202

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1993

数据来源: WILEY

摘要:

AbstractThe neural crest is a transitory and pluripotent structure of the vertebrate embryo composed of cells endowed with developmentally regulated migratory properties. We review here a series of studies carried out bothin vivoandin vitroon the ontogeny of the neural crest in the avian embryo. Throughin vivostudies we established the fate map of the neural crest along the neuraxis prior to the onset of the migration and we demonstrated the crucial role played by the tissue environment in which the crest cells migrate in determining their fate. Moreover, the pathways of neural crest cell migration could also be traced by the quail‐chick marker system and the use of the HNK1/NC1 monoclonal antibody (Mab).A large series of clonal cultures of isolated neural crest cells showed that, at migration time, most crest cells are pluripotent. Some, however, are already committed to a particular pathway of differentiation. The differentiation capacities of the pluripotent progenitors are highly variable from one to the other cell. Rare totipotent progenitors able to give rise to representatives of all the phenotypes (neuronal, glial, melanocytic, and mesectodermal) encountered in neural crest derivatives were also found. As a whole we propose a model according to which totipotent neural crest cells become progressively restricted (according to a stochastic rather than a sequentially ordered mechanism) in their potentialities, while they actively divide during the migration process. At the sites of gangliogenesis, selective forces allow only certain crest cells potentialities to be expressed in each type of peripheral nervous system (PNS) ganglia. © 1993 John Wiley&Sons, I

ISSN:0022-3034    

DOI:10.1002/neu.480240203

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1993

数据来源: WILEY

摘要:

AbstractMultipotent neural crest cells undergo developmental restrictions during embryogenesis and eventually give rise to the neurons and glia of the peripheral nervous system, melanocytes, and pheochromocytes. To understand how neuronal potential is restricted to a subpopulation of crest‐derived cells, we have utilized sensitive markers of early neuronal differentiation to assess neurogenesis in crest‐derived cell populations subjected to defined experimental conditionsin vitroandin vivo. We describe environmental conditions that either (a) result in the irreversible loss of neurogenic potential over a characteristic time course or (b) maintain neurogenic potential among neural crest cells. © 1993 John Wiley&Sons,

ISSN:0022-3034    

DOI:10.1002/neu.480240204

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1993

数据来源: WILEY

摘要:

AbstractMany early migratory neural crest cells are pluripotent in the sense that their progeny are able to generate more than one differentiated phenotype (Sieber‐Blum and Cohen, 1980,Dev. Biol.80:95–106; Baroffio, Dupin, and Le Douarin, 1988,Proc. Natl. Acad. Sci. USA85:5325–5329; Bronner‐Fraser and Fraser, 1988,Nature335:161–164; Sieber‐Blum, 1989a,Science243:1608–1611; Ito and Sieber‐Blum, 1991,Dev. Biol.148:95–106). At trunk levels, the neural crest contains two classes (Sieber‐Blum and Cohen, 1980) and at posterior rhombencephalic levels, three different classes of pluripotent cells (Ito and Sieber‐Blum, 1991). We investigated cell differentiation byin vitroclonal analysis to determine when in development the pool of pluripotent neural crest cells becomes exhausted. The data suggest that different classes of pluripotent cells, precursor cells with more restricted developmental potentials, and apparently committed cells, exist at sites of advanced migration (posterior branchial arches) and even at target sites of neural crest cell differentiation [posterior branchial arches, dorsal root ganglia (DRG), sympathetic ganglia (SG), and epidermal ectoderm]. Some putative classes of pluripotent cells persist well into the second half of embryonic development. These observations have implications for our understanding of the mechanisms that control neural crest cell migration and differentiation. They support the idea that cues originating from the microenvironment affect differentiation of pluripotent neural crest cells. One such signal appears to be brain‐derived neurotrophic factor (BDNF). In the presence of BDNF, but not nerve growth factor (NGF), there is a significant increase in the number of neural crest cells per colony that express a sensory neuron‐specific marker. Because this increase is not accompanied by a corresponding increase in the total number of cells per colony, this suggests that BDNF plays a role in cell type specification. ©

ISSN:0022-3034    

DOI:10.1002/neu.480240205

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1993

数据来源: WILEY

摘要:

AbstractStudies of postnatal chromaffin cells, sympathetic neurons and Small Intensely Fluorescent (SIF) cells have suggested that these cells develop from a common progenitor, the sympathoadrenal (SA) progenitor, whose fate is determined by the relative levels of nerve growth factor (NGF) and glucocorticoid (GC) in its environment (Unsicker et al., 1978,Proc. Natl. Acad. Sci. USA75:3498–3502; Doupe et al., 1985a,J. Neurosci.5:2119–2142). Recent studies have identified such a bipotential SA progenitor in the rat embryo. Surprisingly, this progenitor is initially unresponsive to NGF; neuronal differentiation is instead promoted by fibroblast growth factor (FGF). However, FGF appears to promote NGF responsiveness, suggesting that neuronal differentiation involves a relay or cascade of growth factor action. Furthermore, chromaffin cell differentiation appears to involve two sequential, GC‐dependent events: the inhibition of neuronal differentiation and the induction of epinephrine synthesis. The former event is a prerequisite to the latter. Thus both the chromaffin and neuronal pathways of differentiation follow a series of dependent events, involving changes in the responsiveness of SA progenitors to environmental factors. Such changes correlate with changes in antigenic marker expression that can be observedin vivo. In addition to choosing between neuronal and endocrine fates, SA progenitors must also express an appropriate neurotransmitter phenotype. For example, sympathetic neurons can become either noradrenergic or cholinergic. This cholinergic potential is already present in uncommitted SA progenitors, as evidenced by their ability to synthesize acetylcholine. Recent studies suggest that these cells may have yet other developmental capacities, including the ability to synthesize serotonin. This capacity is consistent with the hypothesis that SA progenitors are closely related to progenitors of enteric neurons, an idea supported by recent observations using novel antigenic markers. The SA progenitor may be, therefore, a “master” neuroendocrine progenitor for the peripheral nervous system. © 1993 John Wiley

ISSN:0022-3034    

DOI:10.1002/neu.480240206

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1993

数据来源: WILEY

摘要:

AbstractThe ENS resembles the brain and differs both physiologically and structurally from any other region of the PNS. Recent experiments in which crest cell migration has been studied with DiI, a replication‐deficient retrovirus, or antibodies that label cells of neural crest origin, have confirmed that both the avian and mammalian bowel are colonized by émigrés from the sacral as well as the vagal level of the neural crest. Components of the extracellular matrix, such as laminin, may play roles in enteric neural and glial development. The observation that an overabundance of laminin develops in the presumptive aganglionic region of the gut inIs/Ismutant mice and is associated with the inability of crest‐derived cells to colonize this region of the bowel has led to the hypothesis that laminin promotes the development of crest‐derived cells as enteric neurons. Premature expression of a neuronal phenotype would cause crest‐derived cells to cease migrating before they complete the colonization of the gut. The acquisition by crest‐derived cells of a nonintegrin, nervespecific, 110 kD laminin‐binding protein when they enter the bowel may enable these cells to respond to laminin differently from their pre‐enteric migrating predecessors. Crest‐derived cells migrating along the vagal pathway to the mammalian gut are transiently catecholaminergic (TC). This phenotype appears to be lost rapidly as the cells enter the bowel and begin to follow their program of terminal differentiation. The appearance and disappearance of TC cells may thus be an example of the effects of the enteric microenvironment on the differentiation of crest‐derived cellsin situ. Crest‐derived cells can be isolated from the enteric microenvironment by immunoselection, a method that takes advantage of the selective expression on the surfaces of crest‐derived cells of certain antigens. One neurotrophin, NT‐3, promotes the development of enteric neurons and gliain vitro. BecausetrkC is expressed in the developing and mature gut, it seems likely that NT‐3 plays a critical role in the development of the ENSin situ.Although the factors that are responsible for the development of the unique properties of the ENS remain unknown, progress made in understanding enteric neuronal development has recently accelerated. The application of new techniques and recently developed probes suggest that the accelerated pace of discovery in this area can be expected to continue.

ISSN:0022-3034    

DOI:10.1002/neu.480240207

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1993

数据来源: WILEY

摘要:

AbstractThe transmitter properties of both developing and mature sympathetic neurons are plastic and can be modulated by a number of environmental cues. Cell culture studies demonstrate that noradrenergic neurons can be induced to become cholinergic and that the expression of neuropeptides can be altered. Similar changes in transmitter phenotype occurin vivo. During development, noradrenergic neurons that innervate eccrine sweat glands acquire cholinergic and peptidergic function. This change is dependent upon interactions with the target tissue. Following injury of sympathetic neurons in developing and adult animals, striking alterations take place in peptide expression. Ciliary neurotrophic factor and cholinergic differentiation factor/leukemia inhibitory factor, members of a family that includes several hematopoeitic cytokines, induce cholinergic function and modulate neuropeptide expression in cultured sympathetic neurons. Studies in progress provide evidence that members of this new cytokine family influence the transmitter phenotype of sympathetic neurons not onlyin vitrobut alsoin vivo. © 1993 John Wiley&Sons, Inc

ISSN:0022-3034    

DOI:10.1002/neu.480240208

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1993

数据来源: WILEY

摘要:

AbstractNeural crest cells migrate extensively and interact with numerous tissues and extracellular matrix components during their movement. Cell marking techniques have shown that neural crest cells in the trunk of the avian embryo migrate through the anterior, but not posterior, half of each sclerotome and avoid the region around the notochord. A possible mechanism to account for this migratory pattern is that neural crest cells may be inhibited from entering the posterior sclerotome and the perinotochordal space. Thus, interactions with other tissue may prescribe the pattern of neural crest cell migration in the trunk. In contrast, interactions between neural crest cells and the extracellular matrix may mediate the primary interactions controlling neural crest cells migration in the head region. © 1993 John Wiley&Sons, Inc

ISSN:0022-3034    

DOI:10.1002/neu.480240209

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1993

数据来源: WILEY

摘要:

AbstractNeural crest cells represent a unique link between axial and peripheral regions of the developing vertebrate head. Although their fates are well catalogued, the issue of their role in spatial organization is less certain. Recent data, particularly on patterns of expression of Hox genes in the hindbrain and crest cells, have raised anew the debate whether a segmental arrangement is the basis for positional specification of craniofacial epithelial and mesenchymal tissues or is but one manifestation of underlying spatial programming processes. The mechanisms of positional specification of sensory neurons derived from the neural crest and placodes are unknown. This review examines the spatial organization of cells and tissues that develop in proximity to sensory neurons; some of these tissues share a common ancestry, others are targets of cranial sensory and motor nerves. All share the necessity of acquiring and expressing site‐specific properties in a functionally integrated manner. This integration occurs in part by coordinating patterns of cell migration, as occurs between migrating crest cells and branchial arch myoblasts. Constant rostro‐caudal relations are maintained among these precursors as they move dorsoventrally from the hindbrain–paraxial regions to establish branchial arches. During this period the interactions among these and other mesenchymal cells are hierarchical; each cell population differentially integrates its past with cues emanating from new microenvironments. Analyses of tissue interactions indicate that neural crest cells play a dominant role in this scenario. © 1993 John Wiley&Son

ISSN:0022-3034    

DOI:10.1002/neu.480240210

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1993

数据来源: WILEY

ISSN:0022-3034    

DOI:10.1002/neu.480240201

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1993

数据来源: WILEY