Blaschko's lines refers to lines of:
Blaschko's lines are characteristic of mosaic conditions of the epidermis and probably represent the routes of ectodermal cell migration from the neural crest. Ref: Rook's textbook of dermatology, 8th edition, Pg 18.4.
Melanocyte migration
Ectodermal cell migration
Mesodermal cell migration
Endodermal cell migration