title: Evidence that a late-emerging population of trunk neural crest cells forms the plastron bones in the turtle Trachemys scripta.
abstract: The origin of the turtle plastron is not known, but these nine bones have been homologized to the exoskeletal components of the clavicles, the interclavicular bone, and gastralia. Earlier evidence from our laboratory showed that the bone-forming cells of the plastron were positive for HNK-1 and PDGFRalpha, two markers of the skeletogenic neural crest. This study looks at the embryonic origin of these plastron-forming cells. We show that the HNK-1+ cells are also positive for p75 and FoxD3, confirming their neural crest identity, and that they originate from the dorsal neural tube of stage 17 turtle embryos, several days after the original wave of neural crest cells have migrated and differentiated. DiI studies show that these are migratory cells, and they can be observed in the lateral regions of the embryo and can be seen forming intramembranous bone in the ventral (plastron) regions. Before migrating ventrally, these late-emerging neural crest cells reside for over a week in a carapacial staging area above the neural tube and vertebrae. It is speculated that this staging area is where they lose the inability to form skeletal cells.
authors.affiliation: Biology Department, Swarthmore College, 500 College Avenue, Swarthmore, PA 19081, USA.
authors.forename: Judith A
authors.initials: JA
authors.lastname: Cebra-Thomas
authors.forename: Erin
authors.initials: E
authors.lastname: Betters
authors.forename: Melinda
authors.initials: M
authors.lastname: Yin
authors.forename: Callie
authors.initials: C
authors.lastname: Plafkin
authors.forename: Kendra
authors.initials: K
authors.lastname: McDow
authors.forename: Scott F
authors.initials: SF
authors.lastname: Gilbert
mesh_terms: D000818:Animals; D018959:CD57 Antigens / Q000378:metabolism; D002454:Cell Differentiation / Q000502:physiology*; D002465:Cell Movement / Q000502:physiology*; D051858:Forkhead Transcription Factors / Q000378:metabolism; D009432:Neural Crest / Q000166:cytology / Q000196:embryology*; D010012:Osteogenesis / Q000502:physiology*; D020796:Receptor, Platelet-Derived Growth Factor alpha / Q000378:metabolism; D014426:Turtles / Q000196:embryology*
chemical_list: D018959:CD57 Antigens; D051858:Forkhead Transcription Factors; D020796:Receptor, Platelet-Derived Growth Factor alpha