Figure 1. Chick embryo confers invasive properties on poorly invasive melanoma cells.

Melanoma cells were treated with CM-DiO and cultured as hanging drops to encourage aggregate formation. Similar sized aggregates were introduced into the neural tube of developing chicken and re-incubated within the egg for 2 days. Embryos injected with (A) mesenchymal-like melanoma cell lines LM- MEL-44, -46, -53 and -77 and (B) epithelial-like melanoma cell lines LM-MEL-28, -34, -42, and -62 were harvested and fluorescence pictures from whole-mounts taken (scale bar = 50 μm). White dotted line indicates the midline of the neural tube. (C) From wholemount images, the cells that migrated away from the neural tube were counted. There was no difference between the number of cells migrating from epithelial-like or mesenchymal-like cell lines. (D) Representative cross-section of chick embryo with schematic melanoma cells represented by green ovals. Yellow dotted arrows indicate typical migratory pathways of neural crest cells, underneath the ectoderm or by the neural tube. Red dotted line outlines the neural tube. Dorsal is to the top. Site of injection is indicated by blue X and the cells that have moved out of the neural tube are indicated by white arrows. (E, F) Cross-sections of trunk embryos showing location of melanoma cells (green) from mesenchymal-like cell line LM-MEL-44 (E) and epithelial-like melanoma cell line LM-MEL-34 (F). Arrows indicate motile melanoma cells located outside the neural tube and arrowheads indicate cells remaining inside the neural tube. The neural tube is outlined by a dotted red line. (scale bar = 100 μm).