Publisher Summary This chapter discusses the sensory receptors in a mammalian skin-nerve in vitro preparation. Recently, a preparation was published that provides single fiber recording from sensory afferents of excised rat skin kept “outside down” under superfusion in an organ bath. Like other in vitro techniques in somatosensory research, it improves experimental control over the environmental conditions in the tissue. The rat saphenous nerve and hind paw skin innervated by that nerve were subcutaneously excised and mounted “outside down” in an organ bath. Natural and electrical stimulations were applied to single fiber receptive fields localized in the exposed corium side of the skin. This involved probing with a blunt glass rod for delineation of the receptive fields and probing with calibrated von Frey bristles for determination of the mechanical thresholds. In addition, the exposure of the corium side of the skin gives direct access to the nerve fibers and endings avoiding the diffusion barriers of epidermis or vascular walls.