Several macro- and microdissectron methods for sampling brain regions have been reported. Large regrons, such as cortex, striatum, and hypothalamus, can be separated either in fresh whole brains (in situ preparation) or dissected out from brain slices with or without a microscope. When more than 2 mg tissue weight is dissected from the brain, the procedure is called macrodissection Rat brain can be macrodissected in situ into seven (Glowinski and Iversen, 1966 ) or seventeen (Gispen et al., 1972 ) major regions