The skin is an essential barrier that keeps fluids in and microbes out and is also a sensory organ, allowing animals to perceive temperature, pressure, and noxious aspects of their surrounding environment (Blanpain and Fuchs, 2006). These sensations are perceived by specific receptors expressed by different cell types located in the skin such as keratinocytes, Merkel cells (MCs), and free nerve endings and are subsequently propagated by sensory neurons of the dorsal root and trigeminal ganglia to the cells of the central nervous system, allowing animals to respond to various environmental stimuli (Lumpkin and Bautista, 2005). MCs are neuroendocrine cells present in the basal layer of the epidermis of vertebrates (Moll et al., 2005; Boulais and Misery, 2007; Lucarz and Brand, 2007). MCs are clustered in touch-sensitive zones of the glabrous and hairy skin, called touch domes, and are densely innervated by slowly adapting type I mechanoreceptor nerve fibers. MCs express intermediate filaments of primitive and simple epithelia such as keratin 8 (K8), K18, or K20 but also express neuropeptides and many components of the presynaptic machinery such as synaptotagmin or Rab3c and transcription factors involved in neuronal cell fate determination (Haeberle et al., 2004). An electrophysiological study demonstrated that MCs are excitable cells (Yamashita et al., 1992) that express voltagegated channels, inducing calcium influx in response to depolarization (Haeberle et al., 2004). Selective destruction of MCs by photoablation (Ikeda et al., 1994) or their loss in mice genetically deficient for MCs (Maricich et al., 2009) abolishes responses of slowly adapting type I mechanoreceptor units, which is consistent with the requirement of MCs to mediate slow adapting mechanotransduction in the skin.