.... Here, we study how increased cell number evolved in the vertebrate central nervous system, investigating the regulation of cell proliferation in the lamprey spinal cord. Markers of proliferation show that a ventricular progenitor zone is found throughout the lamprey spinal cord. We show that inhibition...

... unknown how early vertebrates patterned the neural crest within the ancestral body plan they inherited from invertebrate chordates. Here, using a basal vertebrate, the sea lamprey, we show that homologs of Semaphorin3F (Sema3F) ligand and its Neuropilin (Nrp) receptors show complementary and dynamic...

... inhibition blocks tissue convergence rather than volumetric growth, showing that a conserved molecular mechanism can control convergent morphogenesis through different cell behaviours. Finally, via a comparative morphometric analysis in lamprey, dogfish, zebrafish and mouse, we propose that elongation via...

...Tyler Square; Marek Romášek; David Jandzik; Maria V. Cattell; Michael Klymkowsky; Daniel M. Medeiros Lamprey is one of only two living jawless vertebrates, a group that includes the first vertebrates. Comparisons between lamprey and jawed vertebrates have yielded important insights into the origin...

... head skeleton, we have been analyzing head skeleton development in the agnathan, lamprey. The fibroblast growth factors FGF3 and FGF8 have various roles during head development in jawed vertebrates, including pharyngeal pouch morphogenesis, patterning of the oral skeleton and chondrogenesis. We...

...Sebastian M. Shimeld; Phillip C. J. Donoghue Lampreys and hagfish, which together are known as the cyclostomes or ‘agnathans’, are the only surviving lineages of jawless fish. They diverged early in vertebrate evolution, before the origin of the hinged jaws that are characteristic of gnathostome...

... understanding of vertebrate central nervous system (CNS) evolution. Based on the lamprey, a sister group of the gnathostomes (jawed vertebrates), we identified three lamprey Hedgehog ( Hh ) homologues, which are thought to play central signalling roles in telencephalon patterning. However, unlike...

... Zebrafish Lamprey Medaka The vertebrate central nervous system (CNS) forms along the embryonic anteroposterior (AP) axis from the neural plate, a sheet of ectodermal cells that invaginates and transforms into a cylindrical neural tube. Along the dorsoventral (DV) axis, the closed neural tube...

... separate maculae. Symmetric ears can be obtained experimentally in gnathostomes in several ways, including by manipulation of zebrafish Hedgehog signalling, and it has been suggested that these phenotypes might represent an atavistic condition. We have found,however, that the symmetry of the adult lamprey...

... of the segmental patterning of the central nervous system of agnathan embryos is relevant to our understanding of the origin of the developmental plan of the vertebrate hindbrain. To investigate the neuronal organization of the hindbrain of the Japanese lamprey, Lethenteron japonicum , we retrogradely labeled...

...David W. McCauley; Marianne Bronner-Fraser The neural crest is a vertebrate-specific cell population that contributes to the facial skeleton and other derivatives. We have performed focal DiI injection into the cranial neural tube of the developing lamprey in order to follow the migratory pathways...

..., and agnathan to gnathostome. Isolation and comparison of amphioxus, lamprey and axolotl AP-2 reveals its extensive expansion in the vertebrate dorsal neural tube and pharyngeal arches, implying co-option of AP-2 genes by neural crest cells early in vertebrate evolution. Expression in non-neural ectoderm...

... using in situ hybridization . Phylogenetic analysis revealed that LjPax6 occurs as an sister group of gnathostome Pax6. In lamprey embryos, LjPax6 is expressed in the eye, the nasohypophysial plate, the oral ectoderm and the brain. In the central nervous system, LjPax6 is expressed in clearly delineated...

...Robert M. Langille; Brian K. Hall Lamprey embryos were obtained by artificial fertilization to ascertain the contributions made by the neural crest to the head skeleton. Early-neurula-stage embryos of Petromyzon marinus were subjected to neural crest extirpation along the anterior half from one...