Tissue collection a) Sacrifice and rapidly decapitate mice. Using chilled brain matrix (Ted Pella), cut a thick coronal section from 5mm back from start of cortex until start of cerebellum. Store section in ice-cold Hibernate-A media in 10cm plate on ice until all brains have been dissected. b) Use a razor blade to dissect out midbrain and collect tissue, placing directly into dounce homogenizer.