Methylene blue and organised differentiation in the chick embryo.

The sub-blastodermal administration of methylene blue at 17 h of incubation gives rise to a mosaic of neuroectodermal differentiation with a disruption of the neural axis at 40 h of incubation. These features appear to be due to the rapid and direct movement of this dye into all the cells of the chick embryo blastoderm, and its binding and breakdown of the cytoplasmic ribose nucleotides, due to which neural tube formation is completely inhibited. The findings are confirmed by combined copper sulphate and methylene blue treatment, as copper is a powerful catalyst of methylene blue activity and binds with RNA.