Head morphogenesis in embryonic avian chimeras: evidence for a segmental pattern in the ectoderm corresponding to the neuromeres

Development ◽  
1990 ◽  
Vol 108 (4) ◽  
pp. 543-558 ◽  
Author(s):  
G. Couly ◽  
N.M. Le Douarin

Areas of the superficial cephalic ectoderm, including or excluding the neural fold at the same level, were surgically removed from 3-somite chick embryos and replaced by their counterparts excised from a quail embryo at the same developmental stage. Strips of ectoderm corresponding to the presumptive branchial arches were delineated, thus defining anteroposterior ‘segments’ (designated here as ‘ectomeres’) that coincided with the spatial distribution of neural crest cells arising from the adjacent levels of the neural fold. This discrete ectodermal metamerisation parallels the segmentation of the hindbrain into rhombomeres. It seems, therefore, that not only is the neural crest patterned according to its rhombomeric origin but that the superficial ectoderm covering the branchial arches may be part of a larger developmental unit that includes the entire neurectoderm, i.e., the neural tube and the neural crest.

Development ◽  
1997 ◽  
Vol 124 (2) ◽  
pp. 505-514 ◽  
Author(s):  
S.J. Conway ◽  
D.J. Henderson ◽  
A.J. Copp

Neural crest cells originating in the occipital region of the avian embryo are known to play a vital role in formation of the septum of the cardiac outflow tract and to contribute cells to the aortic arches, thymus, thyroid and parathyroids. This ‘cardiac’ neural crest sub-population is assumed to exist in mammals, but without direct evidence. In this paper we demonstrate, using RT-PCR and in situ hybridisation, that Pax3 expression can serve as a marker of cardiac neural crest cells in the mouse embryo. Cells of this lineage were traced from the occipital neural tube, via branchial arches 3, 4 and 6, into the aortic sac and aorto-pulmonary outflow tract. Confirmation that these Pax3-positive cells are indeed cardiac neural crest is provided by experiments in which hearts were deprived of a source of colonising neural crest, by organ culture in vitro, with consequent lack of up-regulation of Pax3. Occipital neural crest cell outgrowths in vitro were also shown to express Pax3. Mutation of Pax3, as occurs in the splotch (Sp2H) mouse, results in development of conotruncal heart defects including persistent truncus arteriosus. Homozygotes also exhibit defects of the aortic arches, thymus, thyroid and parathyroids. Pax3-positive neural crest cells were found to emigrate from the occipital neural tube of Sp2H/Sp2H embryos in a relatively normal fashion, but there was a marked deficiency or absence of neural crest cells traversing branchial arches 3, 4 and 6, and entering the cardiac outflow tract. This decreased expression of Pax3 in Sp2H/Sp2H embryos was not due to down-regulation of Pax3 in neural crest cells, as use of independent neural crest markers, Hoxa-3, CrabpI, Prx1, Prx2 and c-met also revealed a deficiency of migrating cardiac neural crest cells in homozygous embryos. This work demonstrates the essential role of the cardiac neural crest in formation of the heart and great vessels in the mouse and, furthermore, shows that Pax3 function is required for the cardiac neural crest to complete its migration to the developing heart.


Development ◽  
1991 ◽  
Vol 111 (4) ◽  
pp. 857-866 ◽  
Author(s):  
G.N. Serbedzija ◽  
S. Burgan ◽  
S.E. Fraser ◽  
M. Bronner-Fraser

We have used the vital dye, DiI, to analyze the contribution of sacral neural crest cells to the enteric nervous system in chick and mouse embryos. In order to label premigratory sacral neural crest cells selectively, DiI was injected into the lumen of the neural tube at the level of the hindlimb. In chick embryos, DiI injections made prior to stage 19 resulted in labelled cells in the gut, which had emerged from the neural tube adjacent to somites 29–37. In mouse embryos, neural crest cells emigrated from the sacral neural tube between E9 and E9.5. In both chick and mouse embryos, DiI-labelled cells were observed in the rostral half of the somitic sclerotome, around the dorsal aorta, in the mesentery surrounding the gut, as well as within the epithelium of the gut. Mouse embryos, however, contained consistently fewer labelled cells than chick embryos. DiI-labelled cells first were observed in the rostral and dorsal portion of the gut. Paralleling the maturation of the embryo, there was a rostral-to-caudal sequence in which neural crest cells populated the gut at the sacral level. In addition, neural crest cells appeared within the gut in a dorsal-to-ventral sequence, suggesting that the cells entered the gut dorsally and moved progressively ventrally. The present results resolve a long-standing discrepancy in the literature by demonstrating that sacral neural crest cells in both the chick and mouse contribute to the enteric nervous system in the postumbilical gut.


Development ◽  
1995 ◽  
Vol 121 (4) ◽  
pp. 935-945 ◽  
Author(s):  
E. Birgbauer ◽  
J. Sechrist ◽  
M. Bronner-Fraser ◽  
S. Fraser

Neural crest cell migration in the hindbrain is segmental, with prominent streams of migrating cells adjacent to rhombomeres (r) r2, r4 and r6, but not r3 or r5. This migratory pattern cannot be explained by the failure of r3 and r5 to produce neural crest, since focal injections of the lipophilic dye, DiI, into the neural folds clearly demonstrate that all rhombomeres produce neural crest cells. Here, we examine the dynamics of hindbrain neural crest cell emigration and movement by iontophoretically injecting DiI into small numbers of cells. The intensely labeled cells and their progeny were repeatedly imaged using low-light-level epifluorescence microscopy, permitting their movement to be followed in living embryos over time. These intravital images definitively show that neural crest cells move both rostrally and caudally from r3 and r5 to emerge as a part of the streams adjacent to r2, r4, and/or r6. Within the first few hours, cells labeled in r3 move within and/or along the dorsal neural tube surface, either rostrally toward the r2/3 border or caudally toward the r3/4 border. The labeled cells exit the surface of the neural tube near these borders and migrate toward the first or second branchial arches several hours after initial labeling. Focal DiI injections into r5 resulted in neural crest cell contributions to both the second and third branchial arches, again via rostrocaudal movements of the cells before migration into the periphery. These results demonstrate conclusively that all rhombomeres give rise to neural crest cells, and that rostrocaudal rearrangement of the cells contributes to the segmental migration of neural crest cells adjacent to r2, r4, and r6. Furthermore, it appears that there are consistent exit points of neural crest cell emigration; for example, cells arising from r3 emigrate almost exclusively from the rostral or caudal borders of that rhombomere.


Development ◽  
1996 ◽  
Vol 122 (11) ◽  
pp. 3393-3407 ◽  
Author(s):  
G. Couly ◽  
A. Grapin-Botton ◽  
P. Coltey ◽  
N.M. Le Douarin

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.


2015 ◽  
Vol 26 (5) ◽  
pp. 978-992 ◽  
Author(s):  
Guang Wang ◽  
Yan Li ◽  
Xiao-Yu Wang ◽  
Manli Chuai ◽  
John Yeuk-Hon Chan ◽  
...  

This is the first study of the role of BRE in embryonic development using early chick embryos. BRE is expressed in the developing neural tube, neural crest cells, and somites. BRE thus plays an important role in regulating neurogenesis and indirectly somitogenesis during early chick embryo development.


2004 ◽  
Vol 1 (1) ◽  
pp. 57-63 ◽  
Author(s):  
MEYER BAREMBAUM ◽  
MARIANNE BRONNER-FRASER

Cranial neural crest cells differentiate into diverse derivatives including neurons and glia of the cranial ganglia, and cartilage and bone of the facial skeleton. Here, we explore the function of a novel transcription factor of the spalt family that might be involved in early cell-lineage decisions of the avian neural crest. The chicken spalt4 gene (csal4) is expressed in the neural tube, migrating neural crest, branchial arches and, transiently, in the cranial ectoderm. Later, it is expressed in the mesectodermal, but not neuronal or glial, derivatives of midbrain and hindbrain neural crest. After over-expression by electroporation into the cranial neural tube and neural crest, we observed a marked redistribution of electroporated neural crest cells in the vicinity of the trigeminal ganglion. In control-electroporated embryos, numerous, labeled neural crest cells (∼80% of the population) entered the ganglion, many of which differentiated into neurons. By contrast, few (∼30% of the population) spalt-electroporated neural crest cells entered the trigeminal ganglion. Instead, they localized in the mesenchyme around the ganglionic periphery or continued further ventrally to the branchial arches. Interestingly, little or no expression of differentiation markers for neurons or other cell types was observed in spalt-electroporated neural crest cells.


Development ◽  
1994 ◽  
Vol 120 (7) ◽  
pp. 1777-1790 ◽  
Author(s):  
J. Sechrist ◽  
T. Scherson ◽  
M. Bronner-Fraser

Hindbrain neural crest cells adjacent to rhombomeres 2 (r2), r4 and r6 migrate in a segmental pattern, toward the first, second and third branchial arches, respectively. Although all rhombomeres generate neural crest cells, those arising from r3 and r5 deviate rostrally and caudally (J. Sechrist, G. Serbedzija, T. Scherson, S. Fraser and M. Bronner-Fraser (1993) Development 118, 691–703). We have altered the rostrocaudal positions of the cranial neural tube, adjacent ectoderm/mesoderm or presumptive otic vesicle to examine tissue influences on this segmental migratory pattern. After neural tube rotation, labeled neural crest cells follow pathways generally appropriate for their new position after grafting. For example, when r3 and r4 were transposed, labeled r3 cells migrated laterally to the second branchial arch whereas labeled r4 cells primarily deviated caudally toward the second arch, with some cells moving rostrally toward the first. In contrast to r4 neural crest cells, transposed r3 cells leave the neural tube surface in a polarized manner, near the r3/4 border. Surprisingly, some labeled neural crest cells moved directionally toward small ectopic otic vesicles that often formed in the ectoderm adjacent to grafted r4. Similarly, they moved toward grafted or displaced otic vesicles. In contrast, surgical manipulation of the mesoderm adjacent to r3 and r4 had no apparent effects. Our results offer evidence that neural crest cells migrate directionally toward the otic vesicle, either by selective attraction or pathway-derived cues.


Development ◽  
1989 ◽  
Vol 106 (1) ◽  
pp. 85-93 ◽  
Author(s):  
C. Kalcheim ◽  
M.A. Teillet

We have investigated dorsal root ganglion formation, in the avian embryo, as a function of the composition of the paraxial somitic mesoderm. Three or four contiguous young somites were unilaterally removed from chick embryos and replaced by multiple cranial or caudal half-somites from quail embryos. Migration of neural crest cells and formation of DRG were subsequently visualized both by the HNK-1 antibody and the Feulgen nuclear stain. At advanced migratory stages (as defined by Teillet et al. Devl Biol. 120, 329–347 1987), neural crest cells apposed to the dorsolateral faces of the neural tube were distributed in a continuous, nonsegmented pattern that was indistinguishable on unoperated sides and on sides into which either half of the somites had been grafted. In contrast, ventrolaterally, neural crest cells were distributed segmentally close to the neural tube and within the cranial part of each normal sclerotome, whereas they displayed a nonsegmental distribution when the graft involved multiple cranial half-somites or were virtually absent when multiple caudal half-somites had been implanted. In spite of the identical dorsal distribution of neural crest cells in all embryos, profound differences in the size and segmentation of DRG were observed during gangliogenesis (E4–9) according to the type of graft that had been performed. Thus when the implant consisted of compound cranial half-somites, giant, coalesced ganglia developed, encompassing the entire length of the graft. On the other hand, very small, dorsally located ganglia with irregular segmentation were seen at the level corresponding to the graft of multiple caudal half-somites. We conclude that normal morphogenesis of dorsal root ganglia depends upon the craniocaudal integrity of the somites.


Development ◽  
1993 ◽  
Vol 119 (1) ◽  
pp. 233-245 ◽  
Author(s):  
A. Graham ◽  
I. Heyman ◽  
A. Lumsden

Neural crest cells originate at three discontinuous levels along the rostrocaudal axis of the chick rhombencephalon, centred on rhombomeres 1 and 2, 4 and 6, respectively. These are separated by the odd-numbered rhombomeres r3 and r5 which are depleted of migratory neural crest cells. Here we show elevated levels of apoptosis in the dorsal midline of r3 and r5, immediately following the formation of these rhombomeres at the developmental stage (10–12) when neural crest cells would be expected to emerge at these neuraxial levels. These regions are also marked by their expression of members of the msx family of homeobox genes with msx-2 expression preceding apoptosis in a precisely colocalised pattern. In vitro and in ovo experiments have revealed that r3 and r5 are depleted of neural crest cells by an interaction within the neural epithelium: if isolated or distanced from their normal juxtaposition with even-numbered rhombomeres, both r3 and r5 produce migrating neural crest cells. When r3 or r5 are unconstrained in this way, allowing production of crest, msx-2 expression is concomitantly down regulated. This suggests a correlation between msx-2 and the programming of apoptosis in this system. The hindbrain neural crest is thus produced in discrete streams by mechanisms intrinsic to the neural epithelium. The crest cells that enter the underlying branchial region are organised into streams before they encounter the mesodermal environment lateral to the neural tube. This contrasts sharply with the situation in the trunk where neural crest production is uninterrupted along the neuraxis and the segmental accumulation of neurogenic crest cells is subsequently founded on an alternation of permissive and non-permissive qualities of the local mesodermal environment.


2007 ◽  
Vol 27 (1) ◽  
pp. 45-52
Author(s):  
Koh-ichi Atoh ◽  
Manae S. Kurokawa ◽  
Hideshi Yoshikawa ◽  
Chieko Masuda ◽  
Erika Takada ◽  
...  

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