Fig. 1. ECM collection and carrier transplantation techniques. Polycarbonate carriers were cut and placed under donor epidermis, which was allowed to secrete ECM onto the carrier overnight. This `ECM-conditioned' carrier was then placed, with or without rotation, under an epidermal flap along either the left or the right PND migration pathway of the host embryo. Carriers remained in embryos overnight, followed by fixation, removal of epidermis and analysis of PND location.