Axons arrest the migration of Schwann cell precursors

Development ◽  
1994 ◽  
Vol 120 (6) ◽  
pp. 1411-1420 ◽  
Author(s):  
A. Bhattacharyya ◽  
R. Brackenbury ◽  
N. Ratner
Keyword(s):  
Schwann Cell ◽  
Motor Neuron ◽  
Neural Crest ◽  
Schwann Cells ◽  
Neural Tube ◽  
Neural Crest Cells ◽  
Ventral Root ◽  
Motor Axons ◽  
Ventral Neural Tube ◽  
Schwann Cell Precursors

The neural crest gives rise to a variety of cell types including Schwann cells of the peripheral nervous system. Schwann cell precursors begin to differentiate early and migrate along specific pathways in the embryo before associating with nerve trunks. To determine whether motor axons direct the migration of Schwann cell precursors along specific pathways, we tested the effect of ablating the ventral half of the neural tube, which contains motor neuron cell bodies. The ventral neural tube was removed unilaterally from lumbar regions of chicken embryos at stage 17, when neural crest cells are just beginning to migrate and before motor axons have extended out of the neural tube. At several stages after ventral tube ablation, sections of the lumbar region of these embryos were stained with anti-acetylated tubulin to label developing axons, HNK-1 to label migrating neural crest cells and 1E8 to label Schwann cell precursors. In many embryos the ablation of motor neurons was incomplete. The staining patterns in these embryos support the idea that some Schwann cells are derived from the neural tube. In embryos with complete motor neuron ablation, at stage 18, HNK-1-positive neural crest cells had migrated to normal locations in both control and ablated sides of the embryo, suggesting that motor axons or the ventral neural tube are not required for proper migration of neural crest cells. However, by stage 19, cells that were positive for HNK-1 or 1E8 were no longer seen in the region of the ventral root, nor ventral to the ventral root region. Because Schwann cell precursors require neural-derived factors for their survival in vitro, we tested whether neural crest cells that migrate to the region of the ventral root in ventral neural tube-ablated embryos then die. Nile Blue staining for dead and dying cells in ventral neural tube-ablated embryos provided no evidence for cell death at stage 18. These results suggest that motor axons arrest the migration of Schwann cell precursors during neural crest migration.

The migration of neural crest cells and the growth of motor axons through the rostral half of the chick somite

Development ◽  
1985 ◽  
Vol 90 (1) ◽  
pp. 437-455
Author(s):  
M. Rickmann ◽  
J. W. Fawcett ◽  
R. J. Keynes
Keyword(s):  
Neural Crest ◽  
Neural Tube ◽  
Critical Role ◽  
Neural Crest Cells ◽  
Ventral Root ◽  
Lateral Part ◽  
Motor Axons ◽  
Migration Pathway ◽  
Extracellular Matrix Components ◽  
Pass Through

We have studied the pathway of migration of neural crest cells through the somites of the developing chick embryo, using the monoclonal antibodies NC-1 and HNK-1 to stain them. Crest cells, as they migrate ventrally from the dorsal aspect of the neural tube, pass through the lateral part of the sclerotome, but only through that part of the sclerotome which lies in the rostral half of each somite. This migration pathway is almost identical to the path which presumptive motor axons take when they grow out from the neural tube shortly after the onset of neural crest migration. In order to see whether the ventral root axons are guided along this pathway by neural crest cells, we surgically excised the neural crest from a series of embryos, and examined the pattern of axon outgrowth approximately 24 h later. In somites which contained no neural crest cells, ventral root axons were still found only in the rostral half of the somite, although axonal growth was slightly delayed. These axons were surrounded by sheath cells, which had presumably migrated out of the neural tube, to a point about 50 μm proximal to the growth cones. With appropriate antibodies we found that the extracellular matrix components fibronectin and laminin are evenly distributed between the rostral and caudal halves of the somite. Neither of these molecules therefore plays a critical role in determining the specific pathway of neural crest cells or motor axons through the rostral half of the somite.

The effects of embryonic retinal neurons on neural crest cell differentiation into Schwann cells

Development ◽  
1990 ◽  
Vol 109 (4) ◽  
pp. 925-934 ◽  
Author(s):  
L.C. Smith-Thomas ◽  
A.R. Johnson ◽  
J.W. Fawcett
Keyword(s):  
Schwann Cell ◽  
Neural Crest ◽  
Schwann Cells ◽  
Neural Crest Cell ◽  
Neural Crest Cells ◽  
Cell Types ◽  
Cell Markers ◽  
Ngf Receptor ◽  
S 100 ◽  
The Many

Amongst the many cell types that differentiate from migratory neural crest cells are the Schwann cells of the peripheral nervous system. While it has been demonstrated that Schwann cells will not fully differentiate unless in contact with neurons, the factors that cause neural crest cells to enter the differentiative pathway that leads to Schwann cells are unknown. In a previous paper (Development 105: 251, 1989), we have demonstrated that a proportion of morphologically undifferentiated neural crest cells express the Schwann cell markers 217c and NGF receptor, and later, as they acquire the bipolar morphology typical of Schwann cells in culture, express S-100 and laminin. In the present study, we have grown axons from embryonic retina on neural crest cultures to see whether this has an effect on the differentiation of neural crest cells into Schwann cells. After 4 to 6 days of co-culture, many more cells had acquired bipolar morphology and S-100 staining than in controls with no retinal explant, and most of these cells were within 200 microns of an axon, though not necessarily in contact with axons. However, the number of cells expressing the earliest Schwann cell markers 217c and NGF receptor was not affected by the presence of axons. We conclude that axons produce a factor, which is probably diffusible, and which makes immature Schwann cells differentiate. The factor does not, however, influence the entry of neural crest cells into the earliest stages of the Schwann cell differentiative pathway.

scholarly journals Tissue interactions affecting the migration and differentiation of neural crest cells in the chick embryo

Development ◽  
1991 ◽  
Vol 113 (1) ◽  
pp. 207-216 ◽  
Author(s):  
C.D. Stern ◽  
K.B. Artinger ◽  
M. Bronner-Fraser
Keyword(s):  
Neural Crest ◽  
Neural Tube ◽  
Dorsal Root ◽  
Ganglion Cells ◽  
Neural Crest Cells ◽  
Motor Axons ◽  
Root Region ◽  
Tissue Interactions ◽  
Catecholamine Fluorescence ◽  
Catecholaminergic Cells

A series of microsurgical operations was performed in chick embryos to study the factors that control the polarity, position and differentiation of the sympathetic and dorsal root ganglion cells developing from the neural crest. The neural tube, with or without the notochord, was rotated by 180 degrees dorsoventrally to cause the neural crest cells to emerge ventrally. In some embryos, the notochord was ablated, and in others a second notochord was implanted. Sympathetic differentiation was assessed by catecholamine fluorescence after aldehyde fixation. Neural crest cells emerging from an inverted neural tube migrate in a ventral-to-dorsal direction through the sclerotome, where they become segmented by being restricted to the rostral half of each sclerotome. Both motor axons and neural crest cells avoid the notochord and the extracellular matrix that surrounds it, but motor axons appear also to be attracted to the notochord until they reach its immediate vicinity. The dorsal root ganglia always form adjacent to the neural tube and their dorsoventral orientation follows the direction of migration of the neural crest cells. Differentiation of catecholaminergic cells only occurs near the aorta/mesonephros and in addition requires the proximity of either the ventral neural tube (floor plate/ventral root region) or the notochord. Prior migration of presumptive catecholaminergic cells through the sclerotome, however, is neither required nor sufficient for their adrenergic differentiation.

Expression of Schwann cell markers by mammalian neural crest cells in vitro

Development ◽  
1989 ◽  
Vol 105 (2) ◽  
pp. 251-262 ◽  
Author(s):  
L.C. Smith-Thomas ◽  
J.W. Fawcett
Keyword(s):  
Monoclonal Antibody ◽  
Schwann Cell ◽  
Embryonic Development ◽  
Neural Crest ◽  
Schwann Cells ◽  
Neural Crest Cell ◽  
Neural Crest Cells ◽  
Similar Proportion ◽  
Cell Phenotype ◽  
Cell Markers

During embryonic development, neural crest cells differentiate into a wide variety of cell types including Schwann cells of the peripheral nervous system. In order to establish when neural crest cells first start to express a Schwann cell phenotype immunocytochemical techniques were used to examine rat premigratory neural crest cell cultures for the presence of Schwann cell markers. Cultures were fixed for immunocytochemistry after culture periods ranging from 1 to 24 days. Neural crest cells were identified by their morphology and any neural tube cells remaining in the cultures were identified by their epithelial morphology and immunocytochemically. As early as 1 to 2 days in culture, approximately one third of the neural crest cells stained with m217c, a monoclonal antibody that appears to recognize the same antigen as rat neural antigen-1 (RAN-1). A similar proportion of cells were immunoreactive in cultures stained with 192-IgG, a monoclonal antibody that recognizes the rat nerve growth factor receptor. The number of immunoreactive cells increased with time in culture. After 16 days in culture, nests of cells, many of which had a bipolar morphology, were present in the area previously occupied by neural crest cells. The cells in the nests were often associated with neurons and were immunoreactive for m217c, 192-IgG and antibody to S-100 protein and laminin, indicating that the cells were Schwann cells. At all culture periods examined, neural crest cells did not express glial fibrillary acidic protein. These results demonstrate that cultured premigratory neural crest cells express early Schwann cell markers and that some of these cells differentiate into Schwann cells. These observations suggest that some neural crest cells in vivo may be committed to forming Schwann cells and will do so provided that they then proceed to encounter the correct environmental cues during embryonic development.

The regeneration of the cephalic neural crest, a problem revisited: the regenerating cells originate from the contralateral or from the anterior and posterior neural fold

Development ◽  
1996 ◽  
Vol 122 (11) ◽  
pp. 3393-3407 ◽  
Author(s):  
G. Couly ◽  
A. Grapin-Botton ◽  
P. Coltey ◽  
N.M. Le Douarin
Keyword(s):  
Neural Crest ◽  
Neural Tube ◽  
Hox Genes ◽  
Experimental Situation ◽  
Neural Crest Cells ◽  
Fate Map ◽  
Somite Stage ◽  
Dorsal Neural Tube ◽  
Ventral Neural Tube ◽  
Branchial Arches

The mesencephalic and rhombencephalic levels of origin of the hypobranchial skeleton (lower jaw and hyoid bone) within the neural fold have been determined at the 5-somite stage with a resolution corresponding to each single rhombomere, by means of the quail-chick chimera technique. Expression of certain Hox genes (Hoxa-2, Hoxa-3 and Hoxb-4) was recorded in the branchial arches of chick and quail embryos at embryonic days 3 (E3) and E4. This was a prerequisite for studying the regeneration capacities of the neural crest, after the dorsal neural tube was resected at the mesencephalic and rhombencephalic level. We found first that excisions at the 5-somite stage extending from the midmesencephalon down to r8 are followed by the regeneration of neural crest cells able to compensate for the deficiencies so produced. This confirmed the results of previous authors who made similar excisions at comparable (or older) developmental stages. When a bilateral excision was followed by the unilateral homotopic graft of the dorsal neural tube from a quail embryo, thus mimicking the situation created by a unilateral excision, we found that the migration of the grafted unilateral neural crest (quail-labelled) is bilateral and compensates massively for the missing crest derivatives. The capacity of the intermediate and ventral neural tube to yield neural crest cells was tested by removing the chick rhombencephalic neural tube and replacing it either uni- or bilaterally with a ventral tube coming from a stage-matched quail. No neural crest cells exited from the ventral neural tube but no deficiency in neural crest derivatives was recorded. Crest cells were found to regenerate from the ends of the operated region. This was demonstrated by grafting fragments of quail neural fold at the extremities of the excised territory. Quail neural crest cells were seen migrating longitudinally from both the rostral and caudal ends of the operated region and filling the branchial arches located inbetween. Comparison of the behaviour of neural crest cells in this experimental situation with that showed by their normal fate map revealed that crest cells increase their proliferation rate and change their migratory behaviour without modifying their Hox code.

scholarly journals Early Migrating Neural Crest Cells Can Form Ventral Neural Tube Derivatives When Challenged by Transplantation

1998 ◽  
Vol 203 (2) ◽  
pp. 295-304 ◽  
Author(s):  
Seth Ruffins ◽  
Kristin Bruk Artinger ◽  
Marianne Bronner-Fraser
Keyword(s):  
Neural Crest ◽  
Neural Tube ◽  
Neural Crest Cells ◽  
Ventral Neural Tube

scholarly journals Regulative capacity of the cranial neural tube to form neural crest

Development ◽  
1993 ◽  
Vol 118 (4) ◽  
pp. 1049-1062 ◽  
Author(s):  
T. Scherson ◽  
G. Serbedzija ◽  
S. Fraser ◽  
M. Bronner-Fraser
Keyword(s):  
Neural Crest ◽  
Neural Tube ◽  
Neural Crest Cells ◽  
Neural Tube Closure ◽  
Dorsal Midline ◽  
Dorsal Neural Tube ◽  
Ventral Neural Tube ◽  
Cranial Neural Crest Cells ◽  
The Relationship ◽  
Regulative Capacity

In avian embryos, cranial neural crest cells emigrate from the dorsal midline of the neural tube shortly after neural tube closure. Previous lineage analyses suggest that the neural crest is not a pre-segregated population of cells within the neural tube; instead, a single progenitor in the dorsal neural tube can contribute to neurons in both the central and the peripheral nervous systems (Bronner-Fraser and Fraser, 1989 Neuron 3, 755–766). To explore the relationship between the ‘premigratory’ neural crest cells and the balance of the cells in the neural tube in the midbrain and hindbrain region, we have challenged the fate of these populations by ablating the neural crest either alone or in combination with the adjoining ventral portions of the neural tube. Focal injections of the vital dye, DiI, into the neural tissue bordering the ablated region demonstrate that cells at the same axial level, in the lateral and ventral neural tube, regulate to reconstitute a population of neural crest cells. These cells emigrate from the neural tube, migrate along normal pathways according to their axial level of origin and appear to give rise to a normal range of derivatives. This regulation following ablation suggests that neural tube cells normally destined to form CNS derivatives can adjust their prospective fates to form PNS and other neural crest derivatives until 4.5-6 hours after the time of normal onset of emigration from the neural tube.

The dorsal neural tube organizes the dermamyotome and induces axial myocytes in the avian embryo

Development ◽  
1996 ◽  
Vol 122 (1) ◽  
pp. 231-241 ◽  
Author(s):  
M.S. Spence ◽  
J. Yip ◽  
C.A. Erickson
Keyword(s):  
Neural Crest ◽  
Neural Tube ◽  
Neural Crest Cells ◽  
Intervertebral Discs ◽  
Paraxial Mesoderm ◽  
Avian Embryo ◽  
Dorsal Neural Tube ◽  
Ventral Neural Tube ◽  
Dorsal Ectoderm

Somites, like all axial structures, display dorsoventral polarity. The dorsal portion of the somite forms the dermamyotome, which gives rise to the dermis and axial musculature, whereas the ventromedial somite disperses to generate the sclerotome, which later comprises the vertebrae and intervertebral discs. Although the neural tube and notochord are known to regulate some aspects of this dorsoventral pattern, the precise tissues that initially specify the dermamyotome, and later the myotome from it, have been controversial. Indeed, dorsal and ventral neural tube, notochord, ectoderm and neural crest cells have all been proposed to influence dermamyotome formation or to regulate myocyte differentiation. In this report we describe a series of experimental manipulations in the chick embryo to show that dermamyotome formation is regulated by interactions with the dorsal neural tube. First, we demonstrate that when a neural tube is rotated 180 degrees around its dorsoventral axis, a secondary dermamyotome is induced from what would normally have developed as sclerotome. Second, if we ablate the dorsal neural tube, dermamyotomes are absent in the majority of embryos. Third, if we graft pieces of dorsal neural tube into a ventral position between the notochord and ventral somite, a dermamyotome develops from the sclerotome that is proximate to the graft, and myocytes differentiate. In addition, we also show that myogenesis can be regulated by the dorsal neural tube because when pieces of dorsal neural tube and unsegmented paraxial mesoderm are combined in tissue culture, myocytes differentiate, whereas mesoderm cultures alone do not produce myocytes autonomously. In all of the experimental perturbations in vivo, the dorsal neural tube induced dorsal structures from the mesoderm in the presence of notochord and floorplate, which have been reported previously to induce sclerotome. Thus, we have demonstrated that in the context of the embryonic environment, a dorsalizing signal from the dorsal neural tube can compete with the diffusible ventralizing signal from the notochord. In contrast to dorsal neural tube, pieces of ventral neural tube, dorsal ectoderm or neural crest cells, all of which have been postulated to control dermamyotome formation or to induce myogenesis, either fail to do so or provoke only minimal inductive responses in any of our assays. However, complicating the issue, we find consistent with previous studies that following ablation of the entire neural tube, dermamyotome formation still proceeds adjacent to the dorsal ectoderm. Together these results suggest that, although dorsal ectoderm may be less potent than the dorsal neural tube in inducing dermamyotome, it does nonetheless possess some dermamyotomal-inducing activity. Based on our data and that of others, we propose a model for somite dorsoventral patterning in which competing diffusible signals from the dorsal neural tube and from the notochord/floorplate specify dermamyotome and sclerotome, respectively. In our model, the positioning of the dermamyotome dorsally is due to the absence or reduced levels of the notochord-derived ventralizing signals, as well as to the presence of dominant dorsalizing signals. These dorsal signals are possibly localized and amplified by binding to the basal lamina of the ectoderm, where they can signal the underlying somite, and may also be produced by the ectoderm as well.

The neural tube origin of ventral root sheath cells in the chick embryo

Development ◽  
1987 ◽  
Vol 101 (2) ◽  
pp. 247-254 ◽  
Author(s):  
E.R. Lunn ◽  
J. Scourfield ◽  
R.J. Keynes ◽  
C.D. Stern
Keyword(s):  
Neural Crest ◽  
Neural Tube ◽  
Ventral Root ◽  
Phenotypic Traits ◽  
Motor Axons ◽  
Root Cells ◽  
Root Exit Zone ◽  
Root Sheath ◽  
Embryonic Origin ◽  
Sheath Cells

The embryonic origin of peripheral nerve Schwann/sheath cells is still uncertain. Although the neural crest is known to be an important source, it is not clear whether the ventral neural tube also contributes a progenitor population for motor axons. We have used the techniques of immunohistochemistry, electron microscopy and quail-chick grafting to examine this problem. Immunohistochemistry with monoclonal antibody HNK-1 identified a cluster of immunoreactive cells in the sclerotome, at the site of the future ventral root. With the electron microscope, nucleated cells could not be seen breaching the basal lamina of the neural tube, exclusively in the region of the ventral root and preceding axon outgrowth. After grafting a length of crest-ablated quail neural tube in place of host chick neural tube, a population of quail cells was found localized to the ventral root exit zone, associated with the ventral root axons. Taken together, these observations support the possibility of a neural tube origin for ventral root sheath cells, although we found no evidence for a more extensive migration of these cells. The ventral root cells share certain phenotypic traits, such as HNK-1 immunoreactivity, with neural-crest-derived Schwann cells, but are not necessarily identical to them. We argue that while they may help motor axons to exit the neural tube at the correct position, they are unlikely to guide axons beyond the immediate vicinity of the neural tube.

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