Induction of avian cardiac myogenesis by anterior endoderm.

摘要: An experimental system was devised to study the mechanisms by which cells become committed cardiac myocyte lineage during avian development. Chick tissues from outside fate map of heart (in posterior primitive streak {PPS} a Hamburger & Hamilton stage 4 embryo) were combined with potential inducing quail embryos and cultured in vitro. Species-specific RT-PCR employed detect appearance muscle markers chick Nkx-2.5 (cNkx-2.5), troponin C ventricular myosin heavy chain responder tissues. Using this procedure, we found that 4-5 anterior lateral (AL) endoderm central (AC) mesendoderm, but not AL mesoderm or induced PPS differentiate as myocytes. Induction cardiogenesis accompanied marked decrease expression ρ-globin, implying being myocytes instead blood-forming tissue. These results suggest contains signaling molecules can induce specification early cells. One endoderm, cNkx-2.5, is here described for first time. cNkx-2.5 homeobox-containing gene shares extensive sequence similarity Drosophila tinman, required formation. The mesodermal component 5 onward, determined situ hybridization, strikingly accord heart. By time myocardium endocardium form distinct layers, only myocardium. thus appears be earliest marker fated give rise muscle. SUMMARY