Multiple neural crest tumors, hyperplasia, excessive cell proliferation, the cell death of neural crest cells and melanin pigmentation occurred in newborn mice injected intraperitoneally with heated deionized water. It is thought that these phenomena may not only be associated with the protein denaturation of the membrane structure in the neural crest cells, but also with temperature dependent changes of lipid-lipid and lipid-protein interactions, particularly changes of the mobility of proteins, and that may be a reflection of thermodynamic decrease in entropy that occurs during differentiation.