• MeSH
• centrální nervový systém embryologie   MeSH
• embryo savčí fyziologie   MeSH
• ganglia embryologie   MeSH
• lidé MeSH
• pohyb buněk MeSH
• růst MeSH
• spinální ganglia embryologie   MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH

The cranial neural crest (CNC) arises within the developing central nervous system, but then migrates away from the neural tube in three consecutive streams termed mandibular, hyoid and branchial, respectively, according to the order along the anteroposterior axis. While the process of neural crest emigration generally follows a conserved anterior to posterior sequence across vertebrates, we find that ray-finned fishes (bichir, sterlet, gar, and pike) exhibit several heterochronies in the timing and order of CNC emergence that influences their subsequent migratory patterns. First, emigration of the cranial neural crest in these fishes occurs prematurely compared to other vertebrates, already initiating during early neurulation and well before neural tube closure. Second, delamination of the hyoid stream occurs prior to the more anterior mandibular stream; this is associated with early morphogenesis of key hyoid structures like external gills (bichir), a large opercular flap (gar) or first forming cartilage (pike). In sterlet, the hyoid and branchial CNC cells form a single hyobranchial sheet, which later segregates in concert with second pharyngeal pouch morphogenesis. Taken together, the results show that despite generally conserved migratory patterns, heterochronic alterations in the timing of emigration and pattern of migration of CNC cells accompanies morphological diversity of ray-finned fishes.

• Klíčová slova
• Craniofacial, Evolution, Neural crest, Neurulation, Vertebrates,
• MeSH
• biologická evoluce * MeSH
• crista neuralis cytologie   embryologie   MeSH
• embryo nesavčí cytologie   embryologie   MeSH
• pohyb buněk fyziologie   MeSH
• ryby embryologie   MeSH
• zvířata MeSH
• Check Tag
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Research Support, N.I.H., Extramural MeSH

Cranial neural crest cells populate the future facial region and produce ectomesenchyme-derived tissues, such as cartilage, bone, dermis, smooth muscle, adipocytes, and many others. However, the contribution of individual neural crest cells to certain facial locations and the general spatial clonal organization of the ectomesenchyme have not been determined. We investigated how neural crest cells give rise to clonally organized ectomesenchyme and how this early ectomesenchyme behaves during the developmental processes that shape the face. Using a combination of mouse and zebrafish models, we analyzed individual migration, cell crowd movement, oriented cell division, clonal spatial overlapping, and multilineage differentiation. The early face appears to be built from multiple spatially defined overlapping ectomesenchymal clones. During early face development, these clones remain oligopotent and generate various tissues in a given location. By combining clonal analysis, computer simulations, mouse mutants, and live imaging, we show that facial shaping results from an array of local cellular activities in the ectomesenchyme. These activities mostly involve oriented divisions and crowd movements of cells during morphogenetic events. Cellular behavior that can be recognized as individual cell migration is very limited and short-ranged and likely results from cellular mixing due to the proliferation activity of the tissue. These cellular mechanisms resemble the strategy behind limb bud morphogenesis, suggesting the possibility of common principles and deep homology between facial and limb outgrowth.

• Klíčová slova
• Early face development, clonal envelopes, embryonic development, migration, morphogenesis, neural crest cells,
• MeSH
• anatomické modely MeSH
• buněčná diferenciace * MeSH
• buněčné klony cytologie   MeSH
• crista neuralis cytologie   MeSH
• dánio pruhované MeSH
• ektoderm cytologie   embryologie   MeSH
• exprese genu MeSH
• fenotyp MeSH
• mezoderm cytologie   embryologie   MeSH
• morfogeneze * MeSH
• myši MeSH
• obličej embryologie   MeSH
• organogeneze * MeSH
• pohyb buněk MeSH
• reportérové geny MeSH
• zobrazování trojrozměrné MeSH
• zvířata MeSH
• Check Tag
• myši MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Research Support, N.I.H., Extramural MeSH

Directional migration during embryogenesis and tumor progression faces the challenge that numerous external signals need to converge to precisely control cell movement. The Rho guanine exchange factor (GEF) Trio is especially well suited to relay signals, as it features distinct catalytic domains to activate Rho GTPases. Here, we show that Trio is required for Xenopus cranial neural crest (NC) cell migration and cartilage formation. Trio cell-autonomously controls protrusion formation of NC cells and Trio morphant NC cells show a blebbing phenotype. Interestingly, the Trio GEF2 domain is sufficient to rescue protrusion formation and migration of Trio morphant NC cells. We show that this domain interacts with the DEP/C-terminus of Dishevelled (DVL). DVL - but not a deletion construct lacking the DEP domain - is able to rescue protrusion formation and migration of Trio morphant NC cells. This is likely mediated by activation of Rac1, as we find that DVL rescues Rac1 activity in Trio morphant embryos. Thus, our data provide evidence for a novel signaling pathway, whereby Trio controls protrusion formation of cranial NC cells by interacting with DVL to activate Rac1.

• Klíčová slova
• Cadherin-11, Dishevelled, GEF Trio, Neural crest cell migration, Rho GTPases, Xenopus,
• MeSH
• crista neuralis cytologie   embryologie   MeSH
• fenotyp MeSH
• HEK293 buňky MeSH
• lidé MeSH
• plazmidy genetika   MeSH
• pohyb buněk genetika   MeSH
• protein dishevelled genetika   metabolismus   MeSH
• protein-serin-threoninkinasy genetika   metabolismus   MeSH
• proteinové domény MeSH
• proteiny Xenopus genetika   metabolismus   MeSH
• rac1 protein vázající GTP metabolismus   MeSH
• rhoA protein vázající GTP metabolismus   MeSH
• signální transdukce genetika   MeSH
• transfekce MeSH
• vazba proteinů genetika   MeSH
• výměnné faktory guaninnukleotidů genetika   metabolismus   MeSH
• Xenopus laevis embryologie   MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• DVL1 protein, Xenopus MeSH Prohlížeč
• DVL2 protein, human MeSH Prohlížeč
• Dvl2 protein, Xenopus MeSH Prohlížeč
• protein dishevelled MeSH
• protein-serin-threoninkinasy MeSH
• proteiny Xenopus MeSH
• rac1 protein vázající GTP MeSH
• rhoA protein vázající GTP MeSH
• TRIO protein, human MeSH Prohlížeč
• výměnné faktory guaninnukleotidů MeSH

We have investigated the developmental origin and ultrastructure of avian Merkel cells by electron microscopy and chick/quail transplantation experiments. On embryonic day 3, chick leg primordia were homotopically grafted onto Japanese quail host embryo. Fourteen days later, quail cells that had migrated into grafted chick legs were identified according to the masses of heterochromatin associated with the nucleolus that are characteristic for quail. Both in chick and quail, Merkel cells are usually located in the dermis just below the epidermis. They are placed between nerve terminals either individually or in small groups wrapped in sheaths that are formed by glial cell processes. Occasionally, some Merkel cells appear in nerve fascicles and within Herbst corpuscles. Merkel cells, as well as glial cells, in grafted chicken legs were of quail origin. This finding provides evidence against the epidermal origin of avian Merkel cells and indicates that Merkel cells are derived from neural crest cells that colonise, together with glial cells and melanocytes, the developing limb primordium.

• MeSH
• Coturnix * MeSH
• crista neuralis embryologie   MeSH
• elektronová mikroskopie MeSH
• křepelky a křepelovití embryologie   MeSH
• kuřecí embryo embryologie   MeSH
• Merkelovy buňky ultrastruktura   MeSH
• transplantační chiméra embryologie   MeSH
• zadní končetina embryologie   MeSH
• zvířata MeSH
• Check Tag
• kuřecí embryo embryologie   MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

Cartilage of the vertebrate jaw is derived from cranial neural crest cells that migrate to the first pharyngeal arch and form a dorsal "maxillary" and a ventral "mandibular" condensation. It has been assumed that the former gives rise to palatoquadrate and the latter to Meckel's (mandibular) cartilage. In anamniotes, these condensations were thought to form the framework for the bones of the adult jaw and, in amniotes, appear to prefigure the maxillary and mandibular facial prominences. Here, we directly test the contributions of these neural crest condensations in axolotl and chick embryos, as representatives of anamniote and amniote vertebrate groups, using molecular and morphological markers in combination with vital dye labeling of late-migrating cranial neural crest cells. Surprisingly, we find that both palatoquadrate and Meckel's cartilage derive solely from the ventral "mandibular" condensation. In contrast, the dorsal "maxillary" condensation contributes to trabecular cartilage of the neurocranium and forms part of the frontonasal process but does not contribute to jaw joints as previously assumed. These studies reveal the morphogenetic processes by which cranial neural crest cells within the first arch build the primordia for jaw cartilages and anterior cranium.

• Klíčová slova
• NASA Discipline Evolutionary Biology, Non-NASA Center,
• MeSH
• Ambystoma embryologie   MeSH
• barvení a značení MeSH
• barvicí látky MeSH
• biologická evoluce * MeSH
• biologické modely MeSH
• chrupavka embryologie   ultrastruktura   MeSH
• crista neuralis cytologie   MeSH
• embryo nesavčí MeSH
• fluorescein-5-isothiokyanát MeSH
• hybridizace in situ MeSH
• kuřecí embryo MeSH
• mandibula embryologie   růst a vývoj   MeSH
• maxila embryologie   růst a vývoj   MeSH
• morfogeneze MeSH
• rozvržení tělního plánu MeSH
• zelené fluorescenční proteiny MeSH
• zvířata MeSH
• Check Tag
• kuřecí embryo MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Research Support, U.S. Gov't, Non-P.H.S. MeSH
• Research Support, U.S. Gov't, P.H.S. MeSH
• Názvy látek
• barvicí látky MeSH
• fluorescein-5-isothiokyanát MeSH
• zelené fluorescenční proteiny MeSH