Is [10]. Chambers et al., [11] injected B16F1 melanoma cells into both the veins of the chorioallantoic membrane of E11 chick embryos and the tail vein of mice and examined tumor formation after seven days in chick embryos and after 20 
days in mice. The 22948146 number of tumors for a given number of cells injected was higher in the chick than in the mouse. B16F1 tumors grew in most embryonic chick organs while their growth in the mouse was restricted primarily to the lungs. The chick embryo was also used as model for uveal melanoma [12]. Human uveal or skin melanoma cells wereThe Chick Embryo in Melanoma ResearchFigure 1. Egg preparation and fenestration. (A) Incubator containing eggs. (B) The top of each egg is marked to indicate the location of the embryo (blastoderm). (C) Tools required for fenestration of the eggs are depicted: (from left to right) paper towels, tungsten needle and forceps, 2 egg holding devices, syringe with needle, 80 ethanol, plastic petri dish for egg shell waste, egg piercer, hacksaw, adhesive tape, scissors. (D) A predetermined breaking point is generated after NT-157 biological activity removal of 2 ml albumen to lower the level of the blastoderm. (E) After removal of the shell, the embryo is discernible on the blastoderm (arrow). (F) The egg is sealed with adhesive tape and re-incubated. (G) Capillaries are pulled before transplantation. (H) Working place (stereo-microscope with epi-illumination, diluted black ink, PBS, pipette) and (I) tools (mouth pipette, forceps, tungsten needle) required for transplantation of the cells. doi:10.1371/journal.pone.0053970.ginjected into the optic cup at day E3.5 and tumor growth was followed up to E19. In our experimental system we use the early chick embryo in the primitive streak and somite stages (E2 5) and transplant the melanoma cells into their site of origin, the neural crest, or into ectopic sites, the optic cup or the brain vesicles. Malignant growth can be interpreted as untimely and ectopic re-activation of embryonic genes in adult quiescent stem cell populations. Embryonic genes, transcription factors, and transduction chains regulate cell migration and proliferation in the embryo and become inactivated during differentiation. Re-activation in the adult is associated with malignant growth. Our approach is to bring the melanoma cells back into the original embryonic environment, where the re-activated oncogenes may fulfill their original tasks. Our results indicate, that after transplantation of melanoma cells into their autochthonous environment, the neural crest, the oncogenes can be tamed, and the melanoma cells undergo apoptosis, whereas in ectopic sites they Iloprost web exhibit malignant growth.In 1998, we presented for the first time the embryonic neural tube as site for melanoma cell transplantation [13]. We transplanted SKMel28 melanoma cells into the lumen of the neural tube and observed a spontaneous integration into the neural crest with subsequent physiological neural crest cell migration of the transplanted melanoma cells [14]. Neural crest cell migration becomes directly visible in the live embryo, when the GFP labeled 
B16-F1 mouse melanoma cell line is used [15]. The capability to resume neural crest cell migration depends on the constitutive production of BMP-2 (bone morphogenetic protein-2) and can be ablated by pre-treatment of melanoma cells with the embryonic BMP antagonist noggin [16]. After transplantation into the optic cup the melanoma cells exhibit malignant invasive growth, which.Is [10]. Chambers et al., [11] injected B16F1 melanoma cells into both the veins of the chorioallantoic membrane of E11 chick embryos and the tail vein of mice and examined tumor formation after seven days in chick embryos and after 20 days in mice. The 22948146 number of tumors for a given number of cells injected was higher in the chick than in the mouse. B16F1 tumors grew in most embryonic chick organs while their growth in the mouse was restricted primarily to the lungs. The chick embryo was also used as model for uveal melanoma [12]. Human uveal or skin melanoma cells wereThe Chick Embryo in Melanoma ResearchFigure 1. Egg preparation and fenestration. (A) Incubator containing eggs. (B) The top of each egg is marked to indicate the location of the embryo (blastoderm). (C) Tools required for fenestration of the eggs are depicted: (from left to right) paper towels, tungsten needle and forceps, 2 egg holding devices, syringe with needle, 80 ethanol, plastic petri dish for egg shell waste, egg piercer, hacksaw, adhesive tape, scissors. (D) A predetermined breaking point is generated after removal of 2 ml albumen to lower the level of the blastoderm. (E) After removal of the shell, the embryo is discernible on the blastoderm (arrow). (F) The egg is sealed with adhesive tape and re-incubated. (G) Capillaries are pulled before transplantation. (H) Working place (stereo-microscope with epi-illumination, diluted black ink, PBS, pipette) and (I) tools (mouth pipette, forceps, tungsten needle) required for transplantation of the cells. doi:10.1371/journal.pone.0053970.ginjected into the optic cup at day E3.5 and tumor growth was followed up to E19. In our experimental system we use the early chick embryo in the primitive streak and somite stages (E2 5) and transplant the melanoma cells into their site of origin, the neural crest, or into ectopic sites, the optic cup or the brain vesicles. Malignant growth can be interpreted as untimely and ectopic re-activation of embryonic genes in adult quiescent stem cell populations. Embryonic genes, transcription factors, and transduction chains regulate cell migration and proliferation in the embryo and become inactivated during differentiation. Re-activation in the adult is associated with malignant growth. Our approach is to bring the melanoma cells back into the original embryonic environment, where the re-activated oncogenes may fulfill their original tasks. Our results indicate, that after transplantation of melanoma cells into their autochthonous environment, the neural crest, the oncogenes can be tamed, and the melanoma cells undergo apoptosis, whereas in ectopic sites they exhibit malignant growth.In 1998, we presented for the first time the embryonic neural tube as site for melanoma cell transplantation [13]. We transplanted SKMel28 melanoma cells into the lumen of the neural tube and observed a spontaneous integration into the neural crest with subsequent physiological neural crest cell migration of the transplanted melanoma cells [14]. Neural crest cell migration becomes directly visible in the live embryo, when the GFP labeled B16-F1 mouse melanoma cell line is used [15]. The capability to resume neural crest cell migration depends on the constitutive production of BMP-2 (bone morphogenetic protein-2) and can be ablated by pre-treatment of melanoma cells with the embryonic BMP antagonist noggin [16]. After transplantation into the optic cup the melanoma cells exhibit malignant invasive growth, which.