Direct innervation of sensory fibers from the dorsal root ganglion of the cervical dura mater of rats.

Abstract

Sensory innervation in the cervical dura mater of rats was investigated immunohistochemically in whole tissues and transverse sections of the decalcified vertebral column. To investigate the origin and distribution of sensory innervation in the cervical dura mater. It has been generally accepted that irritation of the cervical structures is one of the major causes of pain in the neck and the upper extremities. Sensory fibers in the cervical dura mater are possible mediators of pain. However, there is little information about sensory innervation in the cervical dura mater, including the epiradicular sheath. Ten Wistar rats were used for wholemount immunohistochemical observations of the cervical dura mater. The vertebral columns of five rats were processed for immunohistochemistry after decalcification. In all specimens, sensory fibers were demonstrated by the peptide immunohistochemistry, and sensory innervation was examined. The cervical dura mater was arbitrarily divided into three areas: ventral, dorsal, dorsal root ganglion. A large number of fibers were in the dorsal root ganglion area and were distributed in the corresponding segments. Some calcitonin gene-related peptide immunoreactive fibers in the dorsal root ganglion were directly innervated from dorsal root ganglion area neurons and did not form nerve bundles, similar to the sinuvertebral nerve. Several immunoreactive fibers were seen in the ventral area; fibers were rarely observed in the dorsal area. A large number of sensory fibers are segmentally distributed in the cervical dura mater, and some of them are directly traced from dorsal root ganglion neurons.