Biolistic transfection and diolistic labeling are techniques in which subcellular-sized particles, coated with DNA and lipophilic dyes, respectively, are propelled into cells. The gene-gun approach is particularly applicable for use on ex vivo organized tissue such as brain slices, where cells are not accessible for transfection with methods used in dissociated cell preparations. This simple and rapid method results in targeting of individual cells in a Golgi-like manner, allowing investigating structural and functional aspects of neuronal development.