The somata of various somatosensory neurons—including mechanoreceptors, thermoreceptors, and nociceptors—are intermingled in the dorsal root ganglion. These neurons’ axons are guided to peripheral targets by different cues. For example, peptidergic nociceptors respond to nerve growth factor and terminate in the stratum spinosum of the epidermis, whereas nonpeptidergic nociceptors respond to gli...